Commit Graph

405 Commits

Author SHA1 Message Date
Steven Rostedt (Google)
bb32500fb9 tracing: Have trace_event_file have ref counters
The following can crash the kernel:

 # cd /sys/kernel/tracing
 # echo 'p:sched schedule' > kprobe_events
 # exec 5>>events/kprobes/sched/enable
 # > kprobe_events
 # exec 5>&-

The above commands:

 1. Change directory to the tracefs directory
 2. Create a kprobe event (doesn't matter what one)
 3. Open bash file descriptor 5 on the enable file of the kprobe event
 4. Delete the kprobe event (removes the files too)
 5. Close the bash file descriptor 5

The above causes a crash!

 BUG: kernel NULL pointer dereference, address: 0000000000000028
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 6 PID: 877 Comm: bash Not tainted 6.5.0-rc4-test-00008-g2c6b6b1029d4-dirty #186
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
 RIP: 0010:tracing_release_file_tr+0xc/0x50

What happens here is that the kprobe event creates a trace_event_file
"file" descriptor that represents the file in tracefs to the event. It
maintains state of the event (is it enabled for the given instance?).
Opening the "enable" file gets a reference to the event "file" descriptor
via the open file descriptor. When the kprobe event is deleted, the file is
also deleted from the tracefs system which also frees the event "file"
descriptor.

But as the tracefs file is still opened by user space, it will not be
totally removed until the final dput() is called on it. But this is not
true with the event "file" descriptor that is already freed. If the user
does a write to or simply closes the file descriptor it will reference the
event "file" descriptor that was just freed, causing a use-after-free bug.

To solve this, add a ref count to the event "file" descriptor as well as a
new flag called "FREED". The "file" will not be freed until the last
reference is released. But the FREE flag will be set when the event is
removed to prevent any more modifications to that event from happening,
even if there's still a reference to the event "file" descriptor.

Link: https://lore.kernel.org/linux-trace-kernel/20231031000031.1e705592@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231031122453.7a48b923@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: f5ca233e2e ("tracing: Increase trace array ref count on enable and filter files")
Reported-by: Beau Belgrave <beaub@linux.microsoft.com>
Tested-by: Beau Belgrave <beaub@linux.microsoft.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-11-01 23:44:44 -04:00
Dan Carpenter
5264a2f4bb tracing: Fix a NULL vs IS_ERR() bug in event_subsystem_dir()
The eventfs_create_dir() function returns error pointers, it never returns
NULL.  Update the check to reflect that.

Link: https://lore.kernel.org/linux-trace-kernel/ff641474-84e2-46a7-9d7a-62b251a1050c@moroto.mountain

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 5790b1fb3d ("eventfs: Remove eventfs_file and just use eventfs_inode")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-20 10:04:25 -04:00
Steven Rostedt (Google)
5ddd8baa48 tracing: Make system_callback() function static
The system_callback() function in trace_events.c is only used within that
file. The "static" annotation was missed.

Fixes: 5790b1fb3d ("eventfs: Remove eventfs_file and just use eventfs_inode")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310051743.y9EobbUr-lkp@intel.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-05 10:49:46 -04:00
Steven Rostedt (Google)
2819f23ac1 eventfs: Use eventfs_remove_events_dir()
The update to removing the eventfs_file changed the way the events top
level directory was handled. Instead of returning a dentry, it now returns
the eventfs_inode. In this changed, the removing of the events top level
directory is not much different than removing any of the other
directories. Because of this, the removal just called eventfs_remove_dir()
instead of eventfs_remove_events_dir().

Although eventfs_remove_dir() does the clean up, it misses out on the
dget() of the ei->dentry done in eventfs_create_events_dir(). It makes
more sense to match eventfs_create_events_dir() with a specific function
eventfs_remove_events_dir() and this specific function can then perform
the dput() to the dentry that had the dget() when it was created.

Fixes: 5790b1fb3d ("eventfs: Remove eventfs_file and just use eventfs_inode")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310051743.y9EobbUr-lkp@intel.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-05 10:49:32 -04:00
Steven Rostedt (Google)
5790b1fb3d eventfs: Remove eventfs_file and just use eventfs_inode
Instead of having a descriptor for every file represented in the eventfs
directory, only have the directory itself represented. Change the API to
send in a list of entries that represent all the files in the directory
(but not other directories). The entry list contains a name and a callback
function that will be used to create the files when they are accessed.

struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry *parent,
						const struct eventfs_entry *entries,
						int size, void *data);

is used for the top level eventfs directory, and returns an eventfs_inode
that will be used by:

struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode *parent,
					 const struct eventfs_entry *entries,
					 int size, void *data);

where both of the above take an array of struct eventfs_entry entries for
every file that is in the directory.

The entries are defined by:

typedef int (*eventfs_callback)(const char *name, umode_t *mode, void **data,
				const struct file_operations **fops);

struct eventfs_entry {
	const char			*name;
	eventfs_callback		callback;
};

Where the name is the name of the file and the callback gets called when
the file is being created. The callback passes in the name (in case the
same callback is used for multiple files), a pointer to the mode, data and
fops. The data will be pointing to the data that was passed in
eventfs_create_dir() or eventfs_create_events_dir() but may be overridden
to point to something else, as it will be used to point to the
inode->i_private that is created. The information passed back from the
callback is used to create the dentry/inode.

If the callback fills the data and the file should be created, it must
return a positive number. On zero or negative, the file is ignored.

This logic may also be used as a prototype to convert entire pseudo file
systems into just-in-time allocation.

The "show_events_dentry" file has been updated to show the directories,
and any files they have.

With just the eventfs_file allocations:

 Before after deltas for meminfo (in kB):

   MemFree:		-14360
   MemAvailable:	-14260
   Buffers:		40
   Cached:		24
   Active:		44
   Inactive:		48
   Inactive(anon):	28
   Active(file):	44
   Inactive(file):	20
   Dirty:		-4
   AnonPages:		28
   Mapped:		4
   KReclaimable:	132
   Slab:		1604
   SReclaimable:	132
   SUnreclaim:		1472
   Committed_AS:	12

 Before after deltas for slabinfo:

   <slab>:		<objects>	[ * <size> = <total>]

   ext4_inode_cache	27		[* 1184 = 31968 ]
   extent_status	102		[*   40 = 4080 ]
   tracefs_inode_cache	144		[*  656 = 94464 ]
   buffer_head		39		[*  104 = 4056 ]
   shmem_inode_cache	49		[*  800 = 39200 ]
   filp			-53		[*  256 = -13568 ]
   dentry		251		[*  192 = 48192 ]
   lsm_file_cache	277		[*   32 = 8864 ]
   vm_area_struct	-14		[*  184 = -2576 ]
   trace_event_file	1748		[*   88 = 153824 ]
   kmalloc-1k		35		[* 1024 = 35840 ]
   kmalloc-256		49		[*  256 = 12544 ]
   kmalloc-192		-28		[*  192 = -5376 ]
   kmalloc-128		-30		[*  128 = -3840 ]
   kmalloc-96		10581		[*   96 = 1015776 ]
   kmalloc-64		3056		[*   64 = 195584 ]
   kmalloc-32		1291		[*   32 = 41312 ]
   kmalloc-16		2310		[*   16 = 36960 ]
   kmalloc-8		9216		[*    8 = 73728 ]

 Free memory dropped by 14,360 kB
 Available memory dropped by 14,260 kB
 Total slab additions in size: 1,771,032 bytes

With this change:

 Before after deltas for meminfo (in kB):

   MemFree:		-12084
   MemAvailable:	-11976
   Buffers:		32
   Cached:		32
   Active:		72
   Inactive:		168
   Inactive(anon):	176
   Active(file):	72
   Inactive(file):	-8
   Dirty:		24
   AnonPages:		196
   Mapped:		8
   KReclaimable:	148
   Slab:		836
   SReclaimable:	148
   SUnreclaim:		688
   Committed_AS:	324

 Before after deltas for slabinfo:

   <slab>:		<objects>	[ * <size> = <total>]

   tracefs_inode_cache	144		[* 656 = 94464 ]
   shmem_inode_cache	-23		[* 800 = -18400 ]
   filp			-92		[* 256 = -23552 ]
   dentry		179		[* 192 = 34368 ]
   lsm_file_cache	-3		[* 32 = -96 ]
   vm_area_struct	-13		[* 184 = -2392 ]
   trace_event_file	1748		[* 88 = 153824 ]
   kmalloc-1k		-49		[* 1024 = -50176 ]
   kmalloc-256		-27		[* 256 = -6912 ]
   kmalloc-128		1864		[* 128 = 238592 ]
   kmalloc-64		4685		[* 64 = 299840 ]
   kmalloc-32		-72		[* 32 = -2304 ]
   kmalloc-16		256		[* 16 = 4096 ]
   total = 721352

 Free memory dropped by 12,084 kB
 Available memory dropped by 11,976 kB
 Total slab additions in size:  721,352 bytes

That's over 2 MB in savings per instance for free and available memory,
and over 1 MB in savings per instance of slab memory.

Link: https://lore.kernel.org/linux-trace-kernel/20231003184059.4924468e@gandalf.local.home
Link: https://lore.kernel.org/linux-trace-kernel/20231004165007.43d79161@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ajay Kaher <akaher@vmware.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-04 17:11:50 -04:00
Zheng Yejian
a1f157c7a3 tracing: Expand all ring buffers individually
The ring buffer of global_trace is set to the minimum size in
order to save memory on boot up and then it will be expand when
some trace feature enabled.

However currently operations under an instance can also cause
global_trace ring buffer being expanded, and the expanded memory
would be wasted if global_trace then not being used.

See following case, we enable 'sched_switch' event in instance 'A', then
ring buffer of global_trace is unexpectedly expanded to be 1410KB, also
the '(expanded: 1408)' from 'buffer_size_kb' of instance is confusing.

  # cd /sys/kernel/tracing
  # mkdir instances/A
  # cat buffer_size_kb
  7 (expanded: 1408)
  # cat instances/A/buffer_size_kb
  1410 (expanded: 1408)
  # echo sched:sched_switch > instances/A/set_event
  # cat buffer_size_kb
  1410
  # cat instances/A/buffer_size_kb
  1410

To fix it, we can:
  - Make 'ring_buffer_expanded' as a member of 'struct trace_array';
  - Make 'ring_buffer_expanded' of instance is defaultly true,
    global_trace is defaultly false;
  - In order not to expose 'global_trace' outside of file
    'kernel/trace/trace.c', introduce trace_set_ring_buffer_expanded()
    to set 'ring_buffer_expanded' as 'true';
  - Pass the expected trace_array to tracing_update_buffers().

Link: https://lore.kernel.org/linux-trace-kernel/20230906091837.3998020-1-zhengyejian1@huawei.com

Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-03 19:02:06 -04:00
Clément Léger
23cce5f254 tracing: relax trace_event_eval_update() execution with cond_resched()
When kernel is compiled without preemption, the eval_map_work_func()
(which calls trace_event_eval_update()) will not be preempted up to its
complete execution. This can actually cause a problem since if another
CPU call stop_machine(), the call will have to wait for the
eval_map_work_func() function to finish executing in the workqueue
before being able to be scheduled. This problem was observe on a SMP
system at boot time, when the CPU calling the initcalls executed
clocksource_done_booting() which in the end calls stop_machine(). We
observed a 1 second delay because one CPU was executing
eval_map_work_func() and was not preempted by the stop_machine() task.

Adding a call to cond_resched() in trace_event_eval_update() allows
other tasks to be executed and thus continue working asynchronously
like before without blocking any pending task at boot time.

Link: https://lore.kernel.org/linux-trace-kernel/20230929191637.416931-1-cleger@rivosinc.com

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-09-30 16:24:55 -04:00
Jinjie Ruan
c8414dab16 eventfs: Fix the NULL pointer dereference bug in eventfs_remove_rec()
Inject fault while probing btrfs.ko, if kstrdup() fails in
eventfs_prepare_ef() in eventfs_add_dir(), it will return ERR_PTR
to assign file->ef. But the eventfs_remove() check NULL in
trace_module_remove_events(), which causes the below NULL
pointer dereference.

As both Masami and Steven suggest, allocater side should handle the
error carefully and remove it, so fix the places where it failed.

 Could not create tracefs 'raid56_write' directory
 Btrfs loaded, zoned=no, fsverity=no
 Unable to handle kernel NULL pointer dereference at virtual address 000000000000001c
 Mem abort info:
   ESR = 0x0000000096000004
   EC = 0x25: DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
   FSC = 0x04: level 0 translation fault
 Data abort info:
   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
 user pgtable: 4k pages, 48-bit VAs, pgdp=0000000102544000
 [000000000000001c] pgd=0000000000000000, p4d=0000000000000000
 Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Modules linked in: btrfs(-) libcrc32c xor xor_neon raid6_pq cfg80211 rfkill 8021q garp mrp stp llc ipv6 [last unloaded: btrfs]
 CPU: 15 PID: 1343 Comm: rmmod Tainted: G                 N 6.5.0+ #40
 Hardware name: linux,dummy-virt (DT)
 pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : eventfs_remove_rec+0x24/0xc0
 lr : eventfs_remove+0x68/0x1d8
 sp : ffff800082d63b60
 x29: ffff800082d63b60 x28: ffffb84b80ddd00c x27: ffffb84b3054ba40
 x26: 0000000000000002 x25: ffff800082d63bf8 x24: ffffb84b8398e440
 x23: ffffb84b82af3000 x22: dead000000000100 x21: dead000000000122
 x20: ffff800082d63bf8 x19: fffffffffffffff4 x18: ffffb84b82508820
 x17: 0000000000000000 x16: 0000000000000000 x15: 000083bc876a3166
 x14: 000000000000006d x13: 000000000000006d x12: 0000000000000000
 x11: 0000000000000001 x10: 00000000000017e0 x9 : 0000000000000001
 x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffffb84b84289804
 x5 : 0000000000000000 x4 : 9696969696969697 x3 : ffff33a5b7601f38
 x2 : 0000000000000000 x1 : ffff800082d63bf8 x0 : fffffffffffffff4
 Call trace:
  eventfs_remove_rec+0x24/0xc0
  eventfs_remove+0x68/0x1d8
  remove_event_file_dir+0x88/0x100
  event_remove+0x140/0x15c
  trace_module_notify+0x1fc/0x230
  notifier_call_chain+0x98/0x17c
  blocking_notifier_call_chain+0x4c/0x74
  __arm64_sys_delete_module+0x1a4/0x298
  invoke_syscall+0x44/0x100
  el0_svc_common.constprop.1+0x68/0xe0
  do_el0_svc+0x1c/0x28
  el0_svc+0x3c/0xc4
  el0t_64_sync_handler+0xa0/0xc4
  el0t_64_sync+0x174/0x178
 Code: 5400052c a90153b3 aa0003f3 aa0103f4 (f9401400)
 ---[ end trace 0000000000000000 ]---
 Kernel panic - not syncing: Oops: Fatal exception
 SMP: stopping secondary CPUs
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Kernel Offset: 0x384b00c00000 from 0xffff800080000000
 PHYS_OFFSET: 0xffffcc5b80000000
 CPU features: 0x88000203,3c020000,1000421b
 Memory Limit: none
 Rebooting in 1 seconds..

Link: https://lore.kernel.org/linux-trace-kernel/20230912134752.1838524-1-ruanjinjie@huawei.com
Link: https://lore.kernel.org/all/20230912025808.668187-1-ruanjinjie@huawei.com/
Link: https://lore.kernel.org/all/20230911052818.1020547-1-ruanjinjie@huawei.com/
Link: https://lore.kernel.org/all/20230909072817.182846-1-ruanjinjie@huawei.com/
Link: https://lore.kernel.org/all/20230908074816.3724716-1-ruanjinjie@huawei.com/

Cc: Ajay Kaher <akaher@vmware.com>
Fixes: 5bdcd5f533 ("eventfs: Implement removal of meta data from eventfs")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-09-12 09:57:01 -04:00
Steven Rostedt (Google)
6fdac58c56 tracing: Remove unused trace_event_file dir field
Now that eventfs structure is used to create the events directory via the
eventfs dynamically allocate code, the "dir" field of the trace_event_file
structure is no longer used. Remove it.

Link: https://lkml.kernel.org/r/20230908022001.580400115@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ajay Kaher <akaher@vmware.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-09-08 23:13:02 -04:00
Steven Rostedt (Google)
f5ca233e2e tracing: Increase trace array ref count on enable and filter files
When the trace event enable and filter files are opened, increment the
trace array ref counter, otherwise they can be accessed when the trace
array is being deleted. The ref counter keeps the trace array from being
deleted while those files are opened.

Link: https://lkml.kernel.org/r/20230907024803.456187066@goodmis.org
Link: https://lore.kernel.org/all/1cb3aee2-19af-c472-e265-05176fe9bd84@huawei.com/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 8530dec63e ("tracing: Add tracing_check_open_get_tr()")
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-09-07 16:05:46 -04:00
Ajay Kaher
27152bceea eventfs: Move tracing/events to eventfs
Up until now, /sys/kernel/tracing/events was no different than any other
part of tracefs. The files and directories within the events directory was
created when the tracefs was mounted, and also created for the instances in
/sys/kernel/tracing/instances/<instance>/events. Most of these files and
directories will never be referenced. Since there are thousands of these
files and directories they spend their time wasting precious memory
resources.

Move the "events" directory to the new eventfs. The eventfs will take the
meta data of the events that they represent and store that. When the files
in the events directory are referenced, the dentry and inodes to represent
them are then created. When the files are no longer referenced, they are
freed. This saves the precious memory resources that were wasted on these
seldom referenced dentries and inodes.

Running the following:

 ~# cat /proc/meminfo /proc/slabinfo  > before.out
 ~# mkdir /sys/kernel/tracing/instances/foo
 ~# cat /proc/meminfo /proc/slabinfo  > after.out

to test the changes produces the following deltas:

Before this change:

 Before after deltas for meminfo:

   MemFree: -32260
   MemAvailable: -21496
   KReclaimable: 21528
   Slab: 22440
   SReclaimable: 21528
   SUnreclaim: 912
   VmallocUsed: 16

 Before after deltas for slabinfo:

   <slab>:		<objects>	[ * <size> = <total>]

   tracefs_inode_cache:	14472		[* 1184 = 17134848]
   buffer_head:		24		[* 168 = 4032]
   hmem_inode_cache:	28		[* 1480 = 41440]
   dentry:		14450		[* 312 = 4508400]
   lsm_inode_cache:	14453		[* 32 = 462496]
   vma_lock:		11		[* 152 = 1672]
   vm_area_struct:	2		[* 184 = 368]
   trace_event_file:	1748		[* 88 = 153824]
   kmalloc-256:		1072		[* 256 = 274432]
   kmalloc-64:		2842		[* 64 = 181888]

 Total slab additions in size: 22,763,400 bytes

With this change:

 Before after deltas for meminfo:

   MemFree: -12600
   MemAvailable: -12580
   Cached: 24
   Active: 12
   Inactive: 68
   Inactive(anon): 48
   Active(file): 12
   Inactive(file): 20
   Dirty: -4
   AnonPages: 68
   KReclaimable: 12
   Slab: 1856
   SReclaimable: 12
   SUnreclaim: 1844
   KernelStack: 16
   PageTables: 36
   VmallocUsed: 16

 Before after deltas for slabinfo:

   <slab>:		<objects>	[ * <size> = <total>]

   tracefs_inode_cache:	108		[* 1184 = 127872]
   buffer_head:		24		[* 168 = 4032]
   hmem_inode_cache:	18		[* 1480 = 26640]
   dentry:		127		[* 312 = 39624]
   lsm_inode_cache:	152		[* 32 = 4864]
   vma_lock:		67		[* 152 = 10184]
   vm_area_struct:	-12		[* 184 = -2208]
   trace_event_file: 	1764		[* 96 = 169344]
   kmalloc-96:		14322		[* 96 = 1374912]
   kmalloc-64:		2814		[* 64 = 180096]
   kmalloc-32:		1103		[* 32 = 35296]
   kmalloc-16:		2308		[* 16 = 36928]
   kmalloc-8:		12800		[* 8 = 102400]

 Total slab additions in size: 2,109,984 bytes

Which is a savings of 20,653,416 bytes (20 MB) per tracing instance.

Link: https://lkml.kernel.org/r/1690568452-46553-10-git-send-email-akaher@vmware.com

Signed-off-by: Ajay Kaher <akaher@vmware.com>
Co-developed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Ching-lin Yu <chinglinyu@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-07-31 11:55:55 -04:00
Steven Rostedt (Google)
ee41106a12 tracing: Require all trace events to have a TRACE_SYSTEM
The creation of the trace event directory requires that a TRACE_SYSTEM is
defined that the trace event directory is added within the system it was
defined in.

The code handled the case where a TRACE_SYSTEM was not added, and would
then add the event at the events directory. But nothing should be doing
this. This code also prevents the implementation of creating dynamic
dentrys for the eventfs system.

As this path has never been hit on correct code, remove it. If it does get
hit, issues a WARN_ON_ONCE() and return ENODEV.

Link: https://lkml.kernel.org/r/1690568452-46553-2-git-send-email-akaher@vmware.com

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Ajay Kaher <akaher@vmware.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-07-30 18:13:33 -04:00
Zheng Yejian
dea499781a tracing: Fix warning in trace_buffered_event_disable()
Warning happened in trace_buffered_event_disable() at
  WARN_ON_ONCE(!trace_buffered_event_ref)

  Call Trace:
   ? __warn+0xa5/0x1b0
   ? trace_buffered_event_disable+0x189/0x1b0
   __ftrace_event_enable_disable+0x19e/0x3e0
   free_probe_data+0x3b/0xa0
   unregister_ftrace_function_probe_func+0x6b8/0x800
   event_enable_func+0x2f0/0x3d0
   ftrace_process_regex.isra.0+0x12d/0x1b0
   ftrace_filter_write+0xe6/0x140
   vfs_write+0x1c9/0x6f0
   [...]

The cause of the warning is in __ftrace_event_enable_disable(),
trace_buffered_event_enable() was called once while
trace_buffered_event_disable() was called twice.
Reproduction script show as below, for analysis, see the comments:
 ```
 #!/bin/bash

 cd /sys/kernel/tracing/

 # 1. Register a 'disable_event' command, then:
 #    1) SOFT_DISABLED_BIT was set;
 #    2) trace_buffered_event_enable() was called first time;
 echo 'cmdline_proc_show:disable_event:initcall:initcall_finish' > \
     set_ftrace_filter

 # 2. Enable the event registered, then:
 #    1) SOFT_DISABLED_BIT was cleared;
 #    2) trace_buffered_event_disable() was called first time;
 echo 1 > events/initcall/initcall_finish/enable

 # 3. Try to call into cmdline_proc_show(), then SOFT_DISABLED_BIT was
 #    set again!!!
 cat /proc/cmdline

 # 4. Unregister the 'disable_event' command, then:
 #    1) SOFT_DISABLED_BIT was cleared again;
 #    2) trace_buffered_event_disable() was called second time!!!
 echo '!cmdline_proc_show:disable_event:initcall:initcall_finish' > \
     set_ftrace_filter
 ```

To fix it, IIUC, we can change to call trace_buffered_event_enable() at
fist time soft-mode enabled, and call trace_buffered_event_disable() at
last time soft-mode disabled.

Link: https://lore.kernel.org/linux-trace-kernel/20230726095804.920457-1-zhengyejian1@huawei.com

Cc: <mhiramat@kernel.org>
Fixes: 0fc1b09ff1 ("tracing: Use temp buffer when filtering events")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-07-28 20:29:51 -04:00
Linus Torvalds
582c161cf3 hardening updates for v6.5-rc1
- Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko)
 
 - Convert strreplace() to return string start (Andy Shevchenko)
 
 - Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook)
 
 - Add missing function prototypes seen with W=1 (Arnd Bergmann)
 
 - Fix strscpy() kerndoc typo (Arne Welzel)
 
 - Replace strlcpy() with strscpy() across many subsystems which were
   either Acked by respective maintainers or were trivial changes that
   went ignored for multiple weeks (Azeem Shaikh)
 
 - Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers)
 
 - Add KUnit tests for strcat()-family
 
 - Enable KUnit tests of FORTIFY wrappers under UML
 
 - Add more complete FORTIFY protections for strlcat()
 
 - Add missed disabling of FORTIFY for all arch purgatories.
 
 - Enable -fstrict-flex-arrays=3 globally
 
 - Tightening UBSAN_BOUNDS when using GCC
 
 - Improve checkpatch to check for strcpy, strncpy, and fake flex arrays
 
 - Improve use of const variables in FORTIFY
 
 - Add requested struct_size_t() helper for types not pointers
 
 - Add __counted_by macro for annotating flexible array size members
 -----BEGIN PGP SIGNATURE-----
 
 iQJKBAABCgA0FiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmSbftQWHGtlZXNjb29r
 QGNocm9taXVtLm9yZwAKCRCJcvTf3G3AJj0MD/9X9jzJzCmsAU+yNldeoAzC84Sk
 GVU3RBxGcTNysL1gZXynkIgigw7DWc4htMGeSABHHwQRVP65JCH1Kw/VqIkyumbx
 9LdX6IklMJb4pRT4PVU3azebV4eNmSjlur2UxMeW54Czm91/6I8RHbJOyAPnOUmo
 2oomGdP/hpEHtKR7hgy8Axc6w5ySwQixh2V5sVZG3VbvCS5WKTmTXbs6puuRT5hz
 iHt7v+7VtEg/Qf1W7J2oxfoghvVBsaRrSLrExWT/oZYh1ZxM7DsCAAoG/IsDgHGA
 9LBXiRECgAFThbHVxLvvKZQMXdVk0i8iXLX43XMKC0wTA+NTyH7wlcQQ4RWNMuo8
 sfA9Qm9gMArXaf64aymr3Uwn20Zan0391HdlbhOJZAE6v3PPJbleUnM58AzD2d3r
 5Lz6AIFBxDImy+3f9iDWgacCT5/PkeiXTHzk9QnKhJyKKtRA58XJxj4q2+rPnGJP
 n4haXqoxD5FJbxdXiGKk31RS0U5HBug7wkOcUrTqDHUbc/QNU2b7dxTKUx+zYtCU
 uV5emPzpF4H4z+91WpO47n9gkMAfwV0lt9S2dwS8pxsgqctbmIan+Jgip7rsqZ2G
 OgLXBsb43eEs+6WgO8tVt/ZHYj9ivGMdrcNcsIfikzNs/xweUJ53k2xSEn2xEa5J
 cwANDmkL6QQK7yfeeg==
 =s0j1
 -----END PGP SIGNATURE-----

Merge tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:
 "There are three areas of note:

  A bunch of strlcpy()->strscpy() conversions ended up living in my tree
  since they were either Acked by maintainers for me to carry, or got
  ignored for multiple weeks (and were trivial changes).

  The compiler option '-fstrict-flex-arrays=3' has been enabled
  globally, and has been in -next for the entire devel cycle. This
  changes compiler diagnostics (though mainly just -Warray-bounds which
  is disabled) and potential UBSAN_BOUNDS and FORTIFY _warning_
  coverage. In other words, there are no new restrictions, just
  potentially new warnings. Any new FORTIFY warnings we've seen have
  been fixed (usually in their respective subsystem trees). For more
  details, see commit df8fc4e934.

  The under-development compiler attribute __counted_by has been added
  so that we can start annotating flexible array members with their
  associated structure member that tracks the count of flexible array
  elements at run-time. It is possible (likely?) that the exact syntax
  of the attribute will change before it is finalized, but GCC and Clang
  are working together to sort it out. Any changes can be made to the
  macro while we continue to add annotations.

  As an example of that last case, I have a treewide commit waiting with
  such annotations found via Coccinelle:

    https://git.kernel.org/linus/adc5b3cb48a049563dc673f348eab7b6beba8a9b

  Also see commit dd06e72e68 for more details.

  Summary:

   - Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko)

   - Convert strreplace() to return string start (Andy Shevchenko)

   - Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook)

   - Add missing function prototypes seen with W=1 (Arnd Bergmann)

   - Fix strscpy() kerndoc typo (Arne Welzel)

   - Replace strlcpy() with strscpy() across many subsystems which were
     either Acked by respective maintainers or were trivial changes that
     went ignored for multiple weeks (Azeem Shaikh)

   - Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers)

   - Add KUnit tests for strcat()-family

   - Enable KUnit tests of FORTIFY wrappers under UML

   - Add more complete FORTIFY protections for strlcat()

   - Add missed disabling of FORTIFY for all arch purgatories.

   - Enable -fstrict-flex-arrays=3 globally

   - Tightening UBSAN_BOUNDS when using GCC

   - Improve checkpatch to check for strcpy, strncpy, and fake flex
     arrays

   - Improve use of const variables in FORTIFY

   - Add requested struct_size_t() helper for types not pointers

   - Add __counted_by macro for annotating flexible array size members"

* tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (54 commits)
  netfilter: ipset: Replace strlcpy with strscpy
  uml: Replace strlcpy with strscpy
  um: Use HOST_DIR for mrproper
  kallsyms: Replace all non-returning strlcpy with strscpy
  sh: Replace all non-returning strlcpy with strscpy
  of/flattree: Replace all non-returning strlcpy with strscpy
  sparc64: Replace all non-returning strlcpy with strscpy
  Hexagon: Replace all non-returning strlcpy with strscpy
  kobject: Use return value of strreplace()
  lib/string_helpers: Change returned value of the strreplace()
  jbd2: Avoid printing outside the boundary of the buffer
  checkpatch: Check for 0-length and 1-element arrays
  riscv/purgatory: Do not use fortified string functions
  s390/purgatory: Do not use fortified string functions
  x86/purgatory: Do not use fortified string functions
  acpi: Replace struct acpi_table_slit 1-element array with flex-array
  clocksource: Replace all non-returning strlcpy with strscpy
  string: use __builtin_memcpy() in strlcpy/strlcat
  staging: most: Replace all non-returning strlcpy with strscpy
  drm/i2c: tda998x: Replace all non-returning strlcpy with strscpy
  ...
2023-06-27 21:24:18 -07:00
Azeem Shaikh
c7dce4c5d9 tracing: Replace all non-returning strlcpy with strscpy
strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

No return values were used, so direct replacement with strlcpy is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230516143956.1367827-1-azeemshaikh38@gmail.com
2023-05-26 13:52:19 -07:00
Steven Rostedt (Google)
4b512860bd tracing: Rename stacktrace field to common_stacktrace
The histogram and synthetic events can use a pseudo event called
"stacktrace" that will create a stacktrace at the time of the event and
use it just like it was a normal field. We have other pseudo events such
as "common_cpu" and "common_timestamp". To stay consistent with that,
convert "stacktrace" to "common_stacktrace". As this was used in older
kernels, to keep backward compatibility, this will act just like
"common_cpu" did with "cpu". That is, "cpu" will be the same as
"common_cpu" unless the event has a "cpu" field. In which case, the
event's field is used. The same is true with "stacktrace".

Also update the documentation to reflect this change.

Link: https://lore.kernel.org/linux-trace-kernel/20230523230913.6860e28d@rorschach.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-05-23 23:38:23 -04:00
Linus Torvalds
b72b5fecc1 tracing updates for 6.3:
- Add function names as a way to filter function addresses
 
 - Add sample module to test ftrace ops and dynamic trampolines
 
 - Allow stack traces to be passed from beginning event to end event for
   synthetic events. This will allow seeing the stack trace of when a task is
   scheduled out and recorded when it gets scheduled back in.
 
 - Add trace event helper __get_buf() to use as a temporary buffer when printing
   out trace event output.
 
 - Add kernel command line to create trace instances on boot up.
 
 - Add enabling of events to instances created at boot up.
 
 - Add trace_array_puts() to write into instances.
 
 - Allow boot instances to take a snapshot at the end of boot up.
 
 - Allow live patch modules to include trace events
 
 - Minor fixes and clean ups
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCY/PaaBQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6qh5iAPoD0LKZzD33rhO5Ec4hoexE0DkqycP3
 dvmOMbCBL8GkxwEA+d2gLz/EquSFm166hc4D79Sn3geCqvkwmy8vQWVjIQc=
 =M82D
 -----END PGP SIGNATURE-----

Merge tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Add function names as a way to filter function addresses

 - Add sample module to test ftrace ops and dynamic trampolines

 - Allow stack traces to be passed from beginning event to end event for
   synthetic events. This will allow seeing the stack trace of when a
   task is scheduled out and recorded when it gets scheduled back in.

 - Add trace event helper __get_buf() to use as a temporary buffer when
   printing out trace event output.

 - Add kernel command line to create trace instances on boot up.

 - Add enabling of events to instances created at boot up.

 - Add trace_array_puts() to write into instances.

 - Allow boot instances to take a snapshot at the end of boot up.

 - Allow live patch modules to include trace events

 - Minor fixes and clean ups

* tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits)
  tracing: Remove unnecessary NULL assignment
  tracepoint: Allow livepatch module add trace event
  tracing: Always use canonical ftrace path
  tracing/histogram: Fix stacktrace histogram Documententation
  tracing/histogram: Fix stacktrace key
  tracing/histogram: Fix a few problems with stacktrace variable printing
  tracing: Add BUILD_BUG() to make sure stacktrace fits in strings
  tracing/histogram: Don't use strlen to find length of stacktrace variables
  tracing: Allow boot instances to have snapshot buffers
  tracing: Add trace_array_puts() to write into instance
  tracing: Add enabling of events to boot instances
  tracing: Add creation of instances at boot command line
  tracing: Fix trace_event_raw_event_synth() if else statement
  samples: ftrace: Make some global variables static
  ftrace: sample: avoid open-coded 64-bit division
  samples: ftrace: Include the nospec-branch.h only for x86
  tracing: Acquire buffer from temparary trace sequence
  tracing/histogram: Wrap remaining shell snippets in code blocks
  tracing/osnoise: No need for schedule_hrtimeout range
  bpf/tracing: Use stage6 of tracing to not duplicate macros
  ...
2023-02-23 10:20:49 -08:00
Wang ShaoBo
7568a21e52 tracing: Remove unnecessary NULL assignment
Remove unnecessary NULL assignment int create_new_subsystem().

Link: https://lkml.kernel.org/r/20221123065124.3982439-1-bobo.shaobowang@huawei.com

Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-02-18 14:34:36 -05:00
Steven Rostedt (Google)
70b5339caf tracing: Make trace_define_field_ext() static
trace_define_field_ext() is not used outside of trace_events.c, it should
be static.

Link: https://lore.kernel.org/oe-kbuild-all/202302130750.679RaRog-lkp@intel.com/

Fixes: b6c7abd1c2 ("tracing: Fix TASK_COMM_LEN in trace event format file")
Reported-by: Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-02-12 20:14:11 -05:00
Yafang Shao
b6c7abd1c2 tracing: Fix TASK_COMM_LEN in trace event format file
After commit 3087c61ed2 ("tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN"),
the content of the format file under
/sys/kernel/tracing/events/task/task_newtask was changed from
  field:char comm[16];    offset:12;    size:16;    signed:0;
to
  field:char comm[TASK_COMM_LEN];    offset:12;    size:16;    signed:0;

John reported that this change breaks older versions of perfetto.
Then Mathieu pointed out that this behavioral change was caused by the
use of __stringify(_len), which happens to work on macros, but not on enum
labels. And he also gave the suggestion on how to fix it:
  :One possible solution to make this more robust would be to extend
  :struct trace_event_fields with one more field that indicates the length
  :of an array as an actual integer, without storing it in its stringified
  :form in the type, and do the formatting in f_show where it belongs.

The result as follows after this change,
$ cat /sys/kernel/tracing/events/task/task_newtask/format
        field:char comm[16];    offset:12;      size:16;        signed:0;

Link: https://lore.kernel.org/lkml/Y+QaZtz55LIirsUO@google.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230210155921.4610-1-laoar.shao@gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230212151303.12353-1-laoar.shao@gmail.com

Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Kajetan Puchalski <kajetan.puchalski@arm.com>
CC: Qais Yousef <qyousef@layalina.io>
Fixes: 3087c61ed2 ("tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN")
Reported-by: John Stultz <jstultz@google.com>
Debugged-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-02-12 10:23:39 -05:00
Steven Rostedt (Google)
c484648083 tracing: Add enabling of events to boot instances
Add the format of:

  trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall

That will create the "foo" instance and enable the sched_switch event
(here were the "sched" system is explicitly specified), the
irq_handler_entry event, and all events under the system initcall.

Link: https://lkml.kernel.org/r/20230207173026.386114535@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-02-07 12:49:56 -05:00
Steven Rostedt (Google)
e6745a4da9 tracing: Add a way to filter function addresses to function names
There's been several times where an event records a function address in
its field and I needed to filter on that address for a specific function
name. It required looking up the function in kallsyms, finding its size,
and doing a compare of "field >= function_start && field < function_end".

But this would change from boot to boot and is unreliable in scripts.
Also, it is useful to have this at boot up, where the addresses will not
be known. For example, on the boot command line:

  trace_trigger="initcall_finish.traceoff if func.function == acpi_init"

To implement this, add a ".function" prefix, that will check that the
field is of size long, and the only operations allowed (so far) are "=="
and "!=".

Link: https://lkml.kernel.org/r/20221219183213.916833763@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-01-25 10:31:11 -05:00
Ross Zwisler
98629dadcd tracing: remove unnecessary trace_trigger ifdef
The trace_trigger command line option introduced by
commit a01fdc897f ("tracing: Add trace_trigger kernel command line option")
doesn't need to depend on the CONFIG_HIST_TRIGGERS kernel config option.

This code doesn't depend on the histogram code, and the run-time
selection of triggers is usable without CONFIG_HIST_TRIGGERS.

Link: https://lore.kernel.org/linux-trace-kernel/20221209003310.1737039-1-zwisler@google.com

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: a01fdc897f ("tracing: Add trace_trigger kernel command line option")
Signed-off-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-12-10 13:36:04 -05:00
Steven Rostedt (Google)
a01fdc897f tracing: Add trace_trigger kernel command line option
Allow triggers to be enabled at kernel boot up. For example:

  trace_trigger="sched_switch.stacktrace if prev_state == 2"

The above will enable the stacktrace trigger on top of the sched_switch
event and only trigger if its prev_state is 2 (TASK_UNINTERRUPTIBLE). Then
at boot up, a stacktrace will trigger and be recorded in the tracing ring
buffer every time the sched_switch happens where the previous state is
TASK_INTERRUPTIBLE.

Another useful trigger would be "traceoff" which can stop tracing on an
event if a field of the event matches a certain value defined by the
filter ("if" statement).

Link: https://lore.kernel.org/linux-trace-kernel/20221020210056.0d8d0a5b@gandalf.local.home

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-11-23 19:08:30 -05:00
Steven Rostedt (Google)
4313e5a613 tracing: Free buffers when a used dynamic event is removed
After 65536 dynamic events have been added and removed, the "type" field
of the event then uses the first type number that is available (not
currently used by other events). A type number is the identifier of the
binary blobs in the tracing ring buffer (known as events) to map them to
logic that can parse the binary blob.

The issue is that if a dynamic event (like a kprobe event) is traced and
is in the ring buffer, and then that event is removed (because it is
dynamic, which means it can be created and destroyed), if another dynamic
event is created that has the same number that new event's logic on
parsing the binary blob will be used.

To show how this can be an issue, the following can crash the kernel:

 # cd /sys/kernel/tracing
 # for i in `seq 65536`; do
     echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events
 # done

For every iteration of the above, the writing to the kprobe_events will
remove the old event and create a new one (with the same format) and
increase the type number to the next available on until the type number
reaches over 65535 which is the max number for the 16 bit type. After it
reaches that number, the logic to allocate a new number simply looks for
the next available number. When an dynamic event is removed, that number
is then available to be reused by the next dynamic event created. That is,
once the above reaches the max number, the number assigned to the event in
that loop will remain the same.

Now that means deleting one dynamic event and created another will reuse
the previous events type number. This is where bad things can happen.
After the above loop finishes, the kprobes/foo event which reads the
do_sys_openat2 function call's first parameter as an integer.

 # echo 1 > kprobes/foo/enable
 # cat /etc/passwd > /dev/null
 # cat trace
             cat-2211    [005] ....  2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196
             cat-2211    [005] ....  2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196
             cat-2211    [005] ....  2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196
             cat-2211    [005] ....  2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196
 # echo 0 > kprobes/foo/enable

Now if we delete the kprobe and create a new one that reads a string:

 # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events

And now we can the trace:

 # cat trace
        sendmail-1942    [002] .....   530.136320: foo: (do_sys_openat2+0x0/0x240) arg1=             cat-2046    [004] .....   530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������"
             cat-2046    [004] .....   530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������"
             cat-2046    [004] .....   530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������"
             cat-2046    [004] .....   530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������"
            bash-1515    [007] .....   534.299093: foo: (do_sys_openat2+0x0/0x240) arg1="kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk���������@��4Z����;Y�����U

And dmesg has:

==================================================================
BUG: KASAN: use-after-free in string+0xd4/0x1c0
Read of size 1 at addr ffff88805fdbbfa0 by task cat/2049

 CPU: 0 PID: 2049 Comm: cat Not tainted 6.1.0-rc6-test+ #641
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
 Call Trace:
  <TASK>
  dump_stack_lvl+0x5b/0x77
  print_report+0x17f/0x47b
  kasan_report+0xad/0x130
  string+0xd4/0x1c0
  vsnprintf+0x500/0x840
  seq_buf_vprintf+0x62/0xc0
  trace_seq_printf+0x10e/0x1e0
  print_type_string+0x90/0xa0
  print_kprobe_event+0x16b/0x290
  print_trace_line+0x451/0x8e0
  s_show+0x72/0x1f0
  seq_read_iter+0x58e/0x750
  seq_read+0x115/0x160
  vfs_read+0x11d/0x460
  ksys_read+0xa9/0x130
  do_syscall_64+0x3a/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 RIP: 0033:0x7fc2e972ade2
 Code: c0 e9 b2 fe ff ff 50 48 8d 3d b2 3f 0a 00 e8 05 f0 01 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24
 RSP: 002b:00007ffc64e687c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
 RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fc2e972ade2
 RDX: 0000000000020000 RSI: 00007fc2e980d000 RDI: 0000000000000003
 RBP: 00007fc2e980d000 R08: 00007fc2e980c010 R09: 0000000000000000
 R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000020f00
 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
  </TASK>

 The buggy address belongs to the physical page:
 page:ffffea00017f6ec0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5fdbb
 flags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff)
 raw: 000fffffc0000000 0000000000000000 ffffea00017f6ec8 0000000000000000
 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
 page dumped because: kasan: bad access detected

 Memory state around the buggy address:
  ffff88805fdbbe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
  ffff88805fdbbf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 >ffff88805fdbbf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                ^
  ffff88805fdbc000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
  ffff88805fdbc080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ==================================================================

This was found when Zheng Yejian sent a patch to convert the event type
number assignment to use IDA, which gives the next available number, and
this bug showed up in the fuzz testing by Yujie Liu and the kernel test
robot. But after further analysis, I found that this behavior is the same
as when the event type numbers go past the 16bit max (and the above shows
that).

As modules have a similar issue, but is dealt with by setting a
"WAS_ENABLED" flag when a module event is enabled, and when the module is
freed, if any of its events were enabled, the ring buffer that holds that
event is also cleared, to prevent reading stale events. The same can be
done for dynamic events.

If any dynamic event that is being removed was enabled, then make sure the
buffers they were enabled in are now cleared.

Link: https://lkml.kernel.org/r/20221123171434.545706e3@gandalf.local.home
Link: https://lore.kernel.org/all/20221110020319.1259291-1-zhengyejian1@huawei.com/

Cc: stable@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Depends-on: e18eb8783e ("tracing: Add tracing_reset_all_online_cpus_unlocked() function")
Depends-on: 5448d44c38 ("tracing: Add unified dynamic event framework")
Depends-on: 6212dd2968 ("tracing/kprobes: Use dyn_event framework for kprobe events")
Depends-on: 065e63f951 ("tracing: Only have rmmod clear buffers that its events were active in")
Depends-on: 575380da8b ("tracing: Only clear trace buffer on module unload if event was traced")
Fixes: 77b44d1b7c ("tracing/kprobes: Rename Kprobe-tracer to kprobe-event")
Reported-by: Zheng Yejian <zhengyejian1@huawei.com>
Reported-by: Yujie Liu <yujie.liu@intel.com>
Reported-by: kernel test robot <yujie.liu@intel.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-11-23 19:07:12 -05:00
Steven Rostedt (Google)
e18eb8783e tracing: Add tracing_reset_all_online_cpus_unlocked() function
Currently the tracing_reset_all_online_cpus() requires the
trace_types_lock held. But only one caller of this function actually has
that lock held before calling it, and the other just takes the lock so
that it can call it. More users of this function is needed where the lock
is not held.

Add a tracing_reset_all_online_cpus_unlocked() function for the one use
case that calls it without being held, and also add a lockdep_assert to
make sure it is held when called.

Then have tracing_reset_all_online_cpus() take the lock internally, such
that callers do not need to worry about taking it.

Link: https://lkml.kernel.org/r/20221123192741.658273220@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-11-23 19:06:11 -05:00
Steven Rostedt (Google)
b2380577d4 tracing: Have filter accept "common_cpu" to be consistent
Make filtering consistent with histograms. As "cpu" can be a field of an
event, allow for "common_cpu" to keep it from being confused with the
"cpu" field of the event.

Link: https://lkml.kernel.org/r/20220820134401.513062765@goodmis.org
Link: https://lore.kernel.org/all/20220820220920.e42fa32b70505b1904f0a0ad@kernel.org/

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 1e3bac71c5 ("tracing/histogram: Rename "cpu" to "common_cpu"")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-08-21 15:56:08 -04:00
Linus Torvalds
76bfd3de34 tracing updates for 5.19:
- The majority of the changes are for fixes and clean ups.
 
 Noticeable changes:
 
 - Rework trace event triggers code to be easier to interact with.
 
 - Support for embedding bootconfig with the kernel (as suppose to having it
   embedded in initram). This is useful for embedded boards without initram
   disks.
 
 - Speed up boot by parallelizing the creation of tracefs files.
 
 - Allow absolute ring buffer timestamps handle timestamps that use more than
   59 bits.
 
 - Added new tracing clock "TAI" (International Atomic Time)
 
 - Have weak functions show up in available_filter_function list as:
    __ftrace_invalid_address___<invalid-offset>
   instead of using the name of the function before it.
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCYpOgXRQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6qjkKAQDbpemxvpFyJlZqT8KgEIXubu+ag2/q
 p0XDHaPS0zF9OQEAjTxg6GMEbnFYl6fzxZtOoEbiaQ7ppfdhRI8t6sSMVA8=
 =+nDD
 -----END PGP SIGNATURE-----

Merge tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "The majority of the changes are for fixes and clean ups.

  Notable changes:

   - Rework trace event triggers code to be easier to interact with.

   - Support for embedding bootconfig with the kernel (as suppose to
     having it embedded in initram). This is useful for embedded boards
     without initram disks.

   - Speed up boot by parallelizing the creation of tracefs files.

   - Allow absolute ring buffer timestamps handle timestamps that use
     more than 59 bits.

   - Added new tracing clock "TAI" (International Atomic Time)

   - Have weak functions show up in available_filter_function list as:
     __ftrace_invalid_address___<invalid-offset> instead of using the
     name of the function before it"

* tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (52 commits)
  ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function
  tracing: Fix comments for event_trigger_separate_filter()
  x86/traceponit: Fix comment about irq vector tracepoints
  x86,tracing: Remove unused headers
  ftrace: Clean up hash direct_functions on register failures
  tracing: Fix comments of create_filter()
  tracing: Disable kcov on trace_preemptirq.c
  tracing: Initialize integer variable to prevent garbage return value
  ftrace: Fix typo in comment
  ftrace: Remove return value of ftrace_arch_modify_*()
  tracing: Cleanup code by removing init "char *name"
  tracing: Change "char *" string form to "char []"
  tracing/timerlat: Do not wakeup the thread if the trace stops at the IRQ
  tracing/timerlat: Print stacktrace in the IRQ handler if needed
  tracing/timerlat: Notify IRQ new max latency only if stop tracing is set
  kprobes: Fix build errors with CONFIG_KRETPROBES=n
  tracing: Fix return value of trace_pid_write()
  tracing: Fix potential double free in create_var_ref()
  tracing: Use strim() to remove whitespace instead of doing it manually
  ftrace: Deal with error return code of the ftrace_process_locs() function
  ...
2022-05-29 10:31:36 -07:00
Yuntao Wang
e4931b824a tracing: Use trace_create_file() to simplify creation of tracefs entries
Creating tracefs entries with tracefs_create_file() followed by pr_warn()
is tedious and repetitive, we can use trace_create_file() to simplify
this process and make the code more readable.

Link: https://lkml.kernel.org/r/20220114131052.534382-1-ytcoode@gmail.com

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-05-26 21:12:52 -04:00
Steven Rostedt (Google)
499f12168a tracing: Have event format check not flag %p* on __get_dynamic_array()
The print fmt check against trace events to make sure that the format does
not use pointers that may be freed from the time of the trace to the time
the event is read, gives a false positive on %pISpc when reading data that
was saved in __get_dynamic_array() when it is perfectly fine to do so, as
the data being read is on the ring buffer.

Link: https://lore.kernel.org/all/20220407144524.2a592ed6@canb.auug.org.au/

Cc: stable@vger.kernel.org
Fixes: 5013f454a3 ("tracing: Add check of trace event print fmts for dereferencing pointers")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-05-25 16:57:37 -04:00
Delyan Kratunov
9c2136be08 sched/tracing: Append prev_state to tp args instead
Commit fa2c3254d7 (sched/tracing: Don't re-read p->state when emitting
sched_switch event, 2022-01-20) added a new prev_state argument to the
sched_switch tracepoint, before the prev task_struct pointer.

This reordering of arguments broke BPF programs that use the raw
tracepoint (e.g. tp_btf programs). The type of the second argument has
changed and existing programs that assume a task_struct* argument
(e.g. for bpf_task_storage access) will now fail to verify.

If we instead append the new argument to the end, all existing programs
would continue to work and can conditionally extract the prev_state
argument on supported kernel versions.

Fixes: fa2c3254d7 (sched/tracing: Don't re-read p->state when emitting sched_switch event, 2022-01-20)
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/c8a6930dfdd58a4a5755fc01732675472979732b.camel@fb.com
2022-05-12 00:37:11 +02:00
Jakob Koschel
ba27d85558 tracing: Remove check of list iterator against head past the loop body
When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lkml.kernel.org/r/20220427170734.819891-5-jakobkoschel@gmail.com

Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-04-27 17:19:31 -04:00
Jakob Koschel
99d8ae4ec8 tracing: Remove usage of list iterator variable after the loop
In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element
[1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Link: https://lkml.kernel.org/r/20220427170734.819891-3-jakobkoschel@gmail.com

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-04-27 17:19:30 -04:00
Linus Torvalds
1bc191051d Tracing updates for 5.18:
- New user_events interface. User space can register an event with the kernel
   describing the format of the event. Then it will receive a byte in a page
   mapping that it can check against. A privileged task can then enable that
   event like any other event, which will change the mapped byte to true,
   telling the user space application to start writing the event to the
   tracing buffer.
 
 - Add new "ftrace_boot_snapshot" kernel command line parameter. When set,
   the tracing buffer will be saved in the snapshot buffer at boot up when
   the kernel hands things over to user space. This will keep the traces that
   happened at boot up available even if user space boot up has tracing as
   well.
 
 - Have TRACE_EVENT_ENUM() also update trace event field type descriptions.
   Thus if a static array defines its size with an enum, the user space trace
   event parsers can still know how to parse that array.
 
 - Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the
   TRACE_EVENT() macro, but will attach to an existing tracepoint. This will
   make one tracepoint be able to trace different content and not be stuck at
   only what the original TRACE_EVENT() macro exports.
 
 - Fixes to tracing error logging.
 
 - Better saving of cmdlines to PIDs when tracing (use the wakeup events for
   mapping).
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCYjiO3RQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6qhQzAQDtek5p80p/zkMGymm14wSH6qq0NdgN
 Kv7fTBwEewUa0gD/UCOVLw4Oj+JtHQhCa3sCGZopmRv0BT1+4UQANqosKQY=
 =Au08
 -----END PGP SIGNATURE-----

Merge tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - New user_events interface. User space can register an event with the
   kernel describing the format of the event. Then it will receive a
   byte in a page mapping that it can check against. A privileged task
   can then enable that event like any other event, which will change
   the mapped byte to true, telling the user space application to start
   writing the event to the tracing buffer.

 - Add new "ftrace_boot_snapshot" kernel command line parameter. When
   set, the tracing buffer will be saved in the snapshot buffer at boot
   up when the kernel hands things over to user space. This will keep
   the traces that happened at boot up available even if user space boot
   up has tracing as well.

 - Have TRACE_EVENT_ENUM() also update trace event field type
   descriptions. Thus if a static array defines its size with an enum,
   the user space trace event parsers can still know how to parse that
   array.

 - Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the
   TRACE_EVENT() macro, but will attach to an existing tracepoint. This
   will make one tracepoint be able to trace different content and not
   be stuck at only what the original TRACE_EVENT() macro exports.

 - Fixes to tracing error logging.

 - Better saving of cmdlines to PIDs when tracing (use the wakeup events
   for mapping).

* tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (30 commits)
  tracing: Have type enum modifications copy the strings
  user_events: Add trace event call as root for low permission cases
  tracing/user_events: Use alloc_pages instead of kzalloc() for register pages
  tracing: Add snapshot at end of kernel boot up
  tracing: Have TRACE_DEFINE_ENUM affect trace event types as well
  tracing: Fix strncpy warning in trace_events_synth.c
  user_events: Prevent dyn_event delete racing with ioctl add/delete
  tracing: Add TRACE_CUSTOM_EVENT() macro
  tracing: Move the defines to create TRACE_EVENTS into their own files
  tracing: Add sample code for custom trace events
  tracing: Allow custom events to be added to the tracefs directory
  tracing: Fix last_cmd_set() string management in histogram code
  user_events: Fix potential uninitialized pointer while parsing field
  tracing: Fix allocation of last_cmd in last_cmd_set()
  user_events: Add documentation file
  user_events: Add sample code for typical usage
  user_events: Add self-test for validator boundaries
  user_events: Add self-test for perf_event integration
  user_events: Add self-test for dynamic_events integration
  user_events: Add self-test for ftrace integration
  ...
2022-03-23 11:40:25 -07:00
Linus Torvalds
3fe2f7446f Changes in this cycle were:
- Cleanups for SCHED_DEADLINE
  - Tracing updates/fixes
  - CPU Accounting fixes
  - First wave of changes to optimize the overhead of the scheduler build,
    from the fast-headers tree - including placeholder *_api.h headers for
    later header split-ups.
  - Preempt-dynamic using static_branch() for ARM64
  - Isolation housekeeping mask rework; preperatory for further changes
  - NUMA-balancing: deal with CPU-less nodes
  - NUMA-balancing: tune systems that have multiple LLC cache domains per node (eg. AMD)
  - Updates to RSEQ UAPI in preparation for glibc usage
  - Lots of RSEQ/selftests, for same
  - Add Suren as PSI co-maintainer
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmI5rg8RHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1hGrw/+M3QOk6fH7G48wjlNnBvcOife6ls+Ni4k
 ixOAcF4JKoixO8HieU5vv0A7yf/83tAa6fpeXeMf1hkCGc0NSlmLtuIux+WOmoAL
 LzCyDEYfiP8KnVh0A1Tui/lK0+AkGo21O6ADhQE2gh8o2LpslOHQMzvtyekSzeeb
 mVxMYQN+QH0m518xdO2D8IQv9ctOYK0eGjmkqdNfntOlytypPZHeNel/tCzwklP/
 dElJUjNiSKDlUgTBPtL3DfpoLOI/0mHF2p6NEXvNyULxSOqJTu8pv9Z2ADb2kKo1
 0D56iXBDngMi9MHIJLgvzsA8gKzHLFSuPbpODDqkTZCa28vaMB9NYGhJ643NtEie
 IXTJEvF1rmNkcLcZlZxo0yjL0fjvPkczjw4Vj27gbrUQeEBfb4mfuI4BRmij63Ep
 qEkgQTJhduCqqrQP1rVyhwWZRk1JNcVug+F6N42qWW3fg1xhj0YSrLai2c9nPez6
 3Zt98H8YGS1Z/JQomSw48iGXVqfTp/ETI7uU7jqHK8QcjzQ4lFK5H4GZpwuqGBZi
 NJJ1l97XMEas+rPHiwMEN7Z1DVhzJLCp8omEj12QU+tGLofxxwAuuOVat3CQWLRk
 f80Oya3TLEgd22hGIKDRmHa22vdWnNQyS0S15wJotawBzQf+n3auS9Q3/rh979+t
 ES/qvlGxTIs=
 =Z8uT
 -----END PGP SIGNATURE-----

Merge tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Cleanups for SCHED_DEADLINE

 - Tracing updates/fixes

 - CPU Accounting fixes

 - First wave of changes to optimize the overhead of the scheduler
   build, from the fast-headers tree - including placeholder *_api.h
   headers for later header split-ups.

 - Preempt-dynamic using static_branch() for ARM64

 - Isolation housekeeping mask rework; preperatory for further changes

 - NUMA-balancing: deal with CPU-less nodes

 - NUMA-balancing: tune systems that have multiple LLC cache domains per
   node (eg. AMD)

 - Updates to RSEQ UAPI in preparation for glibc usage

 - Lots of RSEQ/selftests, for same

 - Add Suren as PSI co-maintainer

* tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits)
  sched/headers: ARM needs asm/paravirt_api_clock.h too
  sched/numa: Fix boot crash on arm64 systems
  headers/prep: Fix header to build standalone: <linux/psi.h>
  sched/headers: Only include <linux/entry-common.h> when CONFIG_GENERIC_ENTRY=y
  cgroup: Fix suspicious rcu_dereference_check() usage warning
  sched/preempt: Tell about PREEMPT_DYNAMIC on kernel headers
  sched/topology: Remove redundant variable and fix incorrect type in build_sched_domains
  sched/deadline,rt: Remove unused parameter from pick_next_[rt|dl]_entity()
  sched/deadline,rt: Remove unused functions for !CONFIG_SMP
  sched/deadline: Use __node_2_[pdl|dle]() and rb_first_cached() consistently
  sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy()
  sched/deadline: Move bandwidth mgmt and reclaim functions into sched class source file
  sched/deadline: Remove unused def_dl_bandwidth
  sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE
  sched/tracing: Don't re-read p->state when emitting sched_switch event
  sched/rt: Plug rt_mutex_setprio() vs push_rt_task() race
  sched/cpuacct: Remove redundant RCU read lock
  sched/cpuacct: Optimize away RCU read lock
  sched/cpuacct: Fix charge percpu cpuusage
  sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies
  ...
2022-03-22 14:39:12 -07:00
Steven Rostedt (Google)
795301d3c2 tracing: Have type enum modifications copy the strings
When an enum is used in the visible parts of a trace event that is
exported to user space, the user space applications like perf and
trace-cmd do not have a way to know what the value of the enum is. To
solve this, at boot up (or module load) the printk formats are modified to
replace the enum with their numeric value in the string output.

Array fields of the event are defined by [<nr-elements>] in the type
portion of the format file so that the user space parsers can correctly
parse the array into the appropriate size chunks. But in some trace
events, an enum is used in defining the size of the array, which once
again breaks the parsing of user space tooling.

This was solved the same way as the print formats were, but it modified
the type strings of the trace event. This caused crashes in some
architectures because, as supposed to the print string, is a const string
value. This was not detected on x86, as it appears that const strings are
still writable (at least in boot up), but other architectures this is not
the case, and writing to a const string will cause a kernel fault.

To fix this, use kstrdup() to copy the type before modifying it. If the
trace event is for the core kernel there's no need to free it because the
string will be in use for the life of the machine being on line. For
modules, create a link list to store all the strings being allocated for
modules and when the module is removed, free them.

Link: https://lore.kernel.org/all/yt9dr1706b4i.fsf@linux.ibm.com/
Link: https://lkml.kernel.org/r/20220318153432.3984b871@gandalf.local.home

Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Fixes: b3bc8547d3 ("tracing: Have TRACE_DEFINE_ENUM affect trace event types as well")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-03-20 10:25:13 -04:00
Steven Rostedt (Google)
b3bc8547d3 tracing: Have TRACE_DEFINE_ENUM affect trace event types as well
The macro TRACE_DEFINE_ENUM is used to convert enums in the kernel to
their actual value when they are exported to user space via the trace
event format file.

Currently only the enums in the "print fmt" (TP_printk in the TRACE_EVENT
macro) have the enums converted. But the enums can be used to denote array
size:

        field:unsigned int fc_ineligible_rc[EXT4_FC_REASON_MAX]; offset:12;      size:36;        signed:0;

The EXT4_FC_REASON_MAX has no meaning to userspace but it needs to know
that information to know how to parse the array.

Have the array indexes also be parsed as well.

Link: https://lore.kernel.org/all/cover.1646922487.git.riteshh@linux.ibm.com/

Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-03-11 11:49:24 -05:00
Steven Rostedt (Google)
8bcd06632b tracing: Allow custom events to be added to the tracefs directory
Allow custom events to be added to the events directory in the tracefs
file system. For example, a module could be installed that attaches to an
event and wants to be enabled and disabled via the tracefs file system. It
would use trace_add_event_call() to add the event to the tracefs
directory, and trace_remove_event_call() to remove it.

Make both those functions EXPORT_SYMBOL_GPL().

Link: https://lkml.kernel.org/r/20220303220625.186988045@goodmis.org

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-03-10 17:41:18 -05:00
Valentin Schneider
fa2c3254d7 sched/tracing: Don't re-read p->state when emitting sched_switch event
As of commit

  c6e7bd7afa ("sched/core: Optimize ttwu() spinning on p->on_cpu")

the following sequence becomes possible:

		      p->__state = TASK_INTERRUPTIBLE;
		      __schedule()
			deactivate_task(p);
  ttwu()
    READ !p->on_rq
    p->__state=TASK_WAKING
			trace_sched_switch()
			  __trace_sched_switch_state()
			    task_state_index()
			      return 0;

TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in
the trace event.

Prevent this by pushing the value read from __schedule() down the trace
event.

Reported-by: Abhijeet Dharmapurikar <adharmap@quicinc.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20220120162520.570782-2-valentin.schneider@arm.com
2022-03-01 16:18:39 +01:00
Steven Rostedt (Google)
c6ced22997 tracing: Update print fmt check to handle new __get_sockaddr() macro
A helper macro was added to make reading socket addresses easier in trace
events. It pairs %pISpc with __get_sockaddr() that reads the socket
address from the ring buffer into a human readable format.

The boot up check that makes sure that trace events do not reference
pointers to memory that can later be freed when the trace event is read,
incorrectly flagged this as a delayed reference. Update the check to
handle "__get_sockaddr" and not report an error on it.

Link: https://lore.kernel.org/all/20220125160505.068dbb52@canb.auug.org.au/

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2022-02-28 10:26:38 -05:00
Yuntao Wang
6e1b4bd191 tracing: Remove duplicate warnings when calling trace_create_file()
Since the same warning message is already printed in the
trace_create_file() function, there is no need to print it again.

Link: https://lkml.kernel.org/r/20220109162232.361747-1-ytcoode@gmail.com

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2022-01-13 17:02:42 -05:00
Steven Rostedt (VMware)
27ff768fa2 tracing: Test the 'Do not trace this pid' case in create event
When creating a new event (via a module, kprobe, eprobe, etc), the
descriptors that are created must add flags for pid filtering if an
instance has pid filtering enabled, as the flags are used at the time the
event is executed to know if pid filtering should be done or not.

The "Only trace this pid" case was added, but a cut and paste error made
that case checked twice, instead of checking the "Trace all but this pid"
case.

Link: https://lore.kernel.org/all/202111280401.qC0z99JB-lkp@intel.com/

Fixes: 6cb206508b ("tracing: Check pid filtering when creating events")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-11-27 16:50:43 -05:00
Steven Rostedt (VMware)
6cb206508b tracing: Check pid filtering when creating events
When pid filtering is activated in an instance, all of the events trace
files for that instance has the PID_FILTER flag set. This determines
whether or not pid filtering needs to be done on the event, otherwise the
event is executed as normal.

If pid filtering is enabled when an event is created (via a dynamic event
or modules), its flag is not updated to reflect the current state, and the
events are not filtered properly.

Cc: stable@vger.kernel.org
Fixes: 3fdaf80f4a ("tracing: Implement event pid filtering")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-11-26 14:31:23 -05:00
Steven Rostedt (VMware)
21ccc9cd72 tracing: Disable "other" permission bits in the tracefs files
When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.

As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.

Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-10-08 18:08:43 -04:00
Steven Rostedt (VMware)
6954e41526 tracing: Place trace_pid_list logic into abstract functions
Instead of having the logic that does trace_pid_list open coded, wrap it in
abstract functions. This will allow a rewrite of the logic that implements
the trace_pid_list without affecting the users.

Note, this causes a change in behavior. Every time a pid is written into
the set_*_pid file, it creates a new list and uses RCU to update it. If
pid_max is lowered, but there was a pid currently in the list that was
higher than pid_max, those pids will now be removed on updating the list.
The old behavior kept that from happening.

The rewrite of the pid_list logic will no longer depend on pid_max,
and will return the old behavior.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-10-05 17:30:08 -04:00
Thomas Gleixner
54357f0c91 tracing: Add migrate-disabled counter to tracing output.
migrate_disable() forbids task migration to another CPU. It is available
since v5.11 and has already users such as highmem or BPF. It is useful
to observe this task state in tracing which already has other states
like the preemption counter.

Instead of adding the migrate disable counter as a new entry to struct
trace_entry, which would extend the whole struct by four bytes, it is
squashed into the preempt-disable counter. The lower four bits represent
the preemption counter, the upper four bits represent the migrate
disable counter. Both counter shouldn't exceed 15 but if they do, there
is a safety net which caps the value at 15.

Add the migrate-disable counter to the trace entry so it shows up in the
trace. Due to the users mentioned above, it is already possible to
observe it:

|  bash-1108    [000] ...21    73.950578: rss_stat: mm_id=2213312838 curr=0 type=MM_ANONPAGES size=8192B
|  bash-1108    [000] d..31    73.951222: irq_disable: caller=flush_tlb_mm_range+0x115/0x130 parent=ptep_clear_flush+0x42/0x50
|  bash-1108    [000] d..31    73.951222: tlb_flush: pages:1 reason:local mm shootdown (3)

The last value is the migrate-disable counter.

Things that popped up:
- trace_print_lat_context() does not print the migrate counter. Not sure
  if it should. It is used in "verbose" mode and uses 8 digits and I'm
  not sure ther is something processing the value.

- trace_define_common_fields() now defines a different variable. This
  probably breaks things. No ide what to do in order to preserve the old
  behaviour. Since this is used as a filter it should be split somehow
  to be able to match both nibbles here.

Link: https://lkml.kernel.org/r/20210810132625.ylssabmsrkygokuv@linutronix.de

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: patch description.]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ SDR: Removed change to common_preempt_count field name ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-09-03 19:42:35 -04:00
Steven Rostedt (VMware)
1d18538e6a tracing: Have dynamic events have a ref counter
As dynamic events are not created by modules, if something is attached to
one, calling "try_module_get()" on its "mod" field, is not going to keep
the dynamic event from going away.

Since dynamic events do not need the "mod" pointer of the event structure,
make a union out of it in order to save memory (there's one structure for
each of the thousand+ events in the kernel), and have any event with the
DYNAMIC flag set to use a ref counter instead.

Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/
Link: https://lkml.kernel.org/r/20210817035027.174869074@goodmis.org

Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-08-18 18:13:47 -04:00
Ingo Molnar
f2cc020d78 tracing: Fix various typos in comments
Fix ~59 single-word typos in the tracing code comments, and fix
the grammar in a handful of places.

Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com
Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-23 14:08:18 -04:00
Steven Rostedt (VMware)
5013f454a3 tracing: Add check of trace event print fmts for dereferencing pointers
Trace events record data into the ring buffer at the time of the event. The
trace event has a printf logic to display the recorded data at a much later
time when the user reads the trace file. This makes using dereferencing
pointers unsafe if the dereferenced pointer points to the original source.
The safe way to handle this is to create an array within the trace event and
copy the source into the array. Then the dereference pointer may point to
that array.

As this is a easy mistake to make, a check is added to examine all trace
event print fmts to make sure that they are safe to use. This only checks
the various %p* dereferenced pointers like %pB, %pR, etc. It does not handle
dereferencing of strings, as there are some use cases that are OK to
dereference the source. That will be dealt with differently.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-03-18 12:58:26 -04:00
Linus Torvalds
c958423470 Tracing updates for 5.12
- Update to the way irqs and preemption is tracked via the trace event PC field
 
  - Fix handling of unregistering event failing due to allocate memory.
    This is only triggered by failure injection, as it is pretty much guaranteed
    to have less than a page allocation succeed.
 
  - Do not show the useless "filter" or "enable" files for the "ftrace" trace
    system, as they have no effect on doing anything.
 
  - Add a warning if kprobes are registered more than once.
 
  - Synthetic events now have their fields parsed by semicolons.
    Old formats without semicolons will still work, but new features will
    require them.
 
  - New option to allow trace events to show %p without hashing in trace file.
    The trace file can only be read by root, and reading the raw event buffer
    did not have any pointers hashed, so this does not expose anything new.
 
  - New directory in tools called tools/tracing, where a new tool that reads
    sequential latency reports from the ftrace latency tracers.
 
  - Other minor fixes and cleanups.
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCYDL2wBQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6qti6AP0RUcSU5U1onx8DcwPQLC5Xr3CPqJkm
 RvKeJDdgFP+sVgEAiMTFsy2UMc0gmlHZMFd5nZLSiJCu1I2hHmhS5yKbHgY=
 =fD9+
 -----END PGP SIGNATURE-----

Merge tag 'trace-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - Update to the way irqs and preemption is tracked via the trace event
   PC field

 - Fix handling of unregistering event failing due to allocate memory.
   This is only triggered by failure injection, as it is pretty much
   guaranteed to have less than a page allocation succeed.

 - Do not show the useless "filter" or "enable" files for the "ftrace"
   trace system, as they have no effect on doing anything.

 - Add a warning if kprobes are registered more than once.

 - Synthetic events now have their fields parsed by semicolons. Old
   formats without semicolons will still work, but new features will
   require them.

 - New option to allow trace events to show %p without hashing in trace
   file. The trace file can only be read by root, and reading the raw
   event buffer did not have any pointers hashed, so this does not
   expose anything new.

 - New directory in tools called tools/tracing, where a new tool that
   reads sequential latency reports from the ftrace latency tracers.

 - Other minor fixes and cleanups.

* tag 'trace-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits)
  kprobes: Fix to delay the kprobes jump optimization
  tracing/tools: Add the latency-collector to tools directory
  tracing: Make hash-ptr option default
  tracing: Add ptr-hash option to show the hashed pointer value
  tracing: Update the stage 3 of trace event macro comment
  tracing: Show real address for trace event arguments
  selftests/ftrace: Add '!event' synthetic event syntax check
  selftests/ftrace: Update synthetic event syntax errors
  tracing: Add a backward-compatibility check for synthetic event creation
  tracing: Update synth command errors
  tracing: Rework synthetic event command parsing
  tracing/dynevent: Delegate parsing to create function
  kprobes: Warn if the kprobe is reregistered
  ftrace: Remove unused ftrace_force_update()
  tracepoints: Code clean up
  tracepoints: Do not punish non static call users
  tracepoints: Remove unnecessary "data_args" macro parameter
  tracing: Do not create "enable" or "filter" files for ftrace event subsystem
  kernel: trace: preemptirq_delay_test: add cpu affinity
  tracepoint: Do not fail unregistering a probe due to memory failure
  ...
2021-02-22 14:07:15 -08:00