From the x86_64 low level interrupt handlers, the frame pointer is
saved right after the partial pt_regs frame.
rbp is not supposed to be part of the irq partial saved registers,
but it only requires to extend the pt_regs frame by 8 bytes to
do so, plus a tiny stack offset fixup on irq exit.
This changes a bit the semantics or get_irq_entry() that is supposed
to provide only the value of caller saved registers and the cpu
saved frame. However it's a win for unwinders that can walk through
stack frames on top of get_irq_regs() snapshots.
A noticeable impact is that it makes perf events cpu-clock and
task-clock events based callchains working on x86_64.
Let's then save rbp into the irq pt_regs.
As a result with:
perf record -e cpu-clock perf bench sched messaging
perf report --stdio
Before:
20.94% perf [kernel.kallsyms] [k] lock_acquire
|
--- lock_acquire
|
|--44.01%-- __write_nocancel
|
|--43.18%-- __read
|
|--6.08%-- fork
| create_worker
|
|--0.88%-- _dl_fixup
|
|--0.65%-- do_lookup_x
|
|--0.53%-- __GI___libc_read
--4.67%-- [...]
After:
19.23% perf [kernel.kallsyms] [k] __lock_acquire
|
--- __lock_acquire
|
|--97.74%-- lock_acquire
| |
| |--21.82%-- _raw_spin_lock
| | |
| | |--37.26%-- unix_stream_recvmsg
| | | sock_aio_read
| | | do_sync_read
| | | vfs_read
| | | sys_read
| | | system_call
| | | __read
| | |
| | |--24.09%-- unix_stream_sendmsg
| | | sock_aio_write
| | | do_sync_write
| | | vfs_write
| | | sys_write
| | | system_call
| | | __write_nocancel
v2: Fix cfi annotations.
Reported-by: Soeren Sandmann Pedersen <sandmann@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jan Beulich <JBeulich@novell.com>
Prevent kprobes to probe on save_args() since this function
will be called from breakpoint exception handler. That will
cause infinit loop on breakpoint handling.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20101118101655.2779.2816.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'softirq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
softirqs: Make wakeup_softirqd static
* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, asm: Restore parentheses around one pushl_cfi argument
x86, asm: Fix ancient-GAS workaround
x86, asm: Fix CFI macro invocations to deal with shortcomings in gas
* 'x86-numa-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, numa: Assign CPUs to nodes in round-robin manner on fake NUMA
* 'x86-quirks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: HPET force enable for CX700 / VIA Epia LT
* 'x86-setup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, setup: Use string copy operation to optimze copy in kernel compression
* 'x86-uv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, UV: Use allocated buffer in tlb_uv.c:tunables_read()
* 'x86-vm86-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, vm86: Fix preemption bug for int1 debug and int3 breakpoint handlers.
* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Remove pr_<level> uses of KERN_<level>
therm_throt.c: Trivial printk message fix for a unsuitable abbreviation of 'thermal'
x86: Use {push,pop}{l,q}_cfi in more places
i386: Add unwind directives to syscall ptregs stubs
x86-64: Use symbolics instead of raw numbers in entry_64.S
x86-64: Adjust frame type at paranoid_exit:
x86-64: Fix unwind annotations in syscall stubs
gas prior to (perhaps) 2.16.90 has problems with passing non-
parenthesized expressions containing spaces to macros. Spaces, however,
get inserted by cpp between any macro expanding to a number and a
subsequent + or -. For the +, current x86 gas then removes the space
again (future gas may not do so), but for the - the space gets retained
and is then considered a separator between macro arguments.
Fix the respective definitions for both the - and + cases, so that they
neither contain spaces nor make cpp insert any (the latter by adding
seemingly redundant parentheses).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4CBDBEBA020000780001E05A@vpn.id2.novell.com>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Provide a mechanism that allows running code in IRQ context. It is
most useful for NMI code that needs to interact with the rest of the
system -- like wakeup a task to drain buffers.
Perf currently has such a mechanism, so extract that and provide it as
a generic feature, independent of perf so that others may also
benefit.
The IRQ context callback is generated through self-IPIs where
possible, or on architectures like powerpc the decrementer (the
built-in timer facility) is set to generate an interrupt immediately.
Architectures that don't have anything like this get to do with a
callback from the timer tick. These architectures can call
irq_work_run() at the tail of any IRQ handlers that might enqueue such
work (like the perf IRQ handler) to avoid undue latencies in
processing the work.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[ various fixes ]
Signed-off-by: Huang Ying <ying.huang@intel.com>
LKML-Reference: <1287036094.7768.291.camel@yhuang-dev>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
... plus additionally introduce {push,pop}f{l,q}_cfi. All in the
hope that the code becomes better readable this way (it gets
quite a bit smaller in any case).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
LKML-Reference: <4C7FBDA40200007800013FAF@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
... making the code a little less fragile.
Also use pushq_cfi instead of raw CFI annotations in two more
places, and add two missing annotations after stack pointer
adjustments which got modified here anyway.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
LKML-Reference: <4C7FBACF0200007800013F6A@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
As this isn't an exception or interrupt entry point, it doesn't
have any of the hardware provide frame layouts active.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
LKML-Reference: <4C7FBAA80200007800013F67@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
With the return address removed from the stack, these should
really refer to their caller's register state.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
LKML-Reference: <4C7FBA3D0200007800013F61@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Mark arguments to certain system calls as being const where they should be but
aren't. The list includes:
(*) The filename arguments of various stat syscalls, execve(), various utimes
syscalls and some mount syscalls.
(*) The filename arguments of some syscall helpers relating to the above.
(*) The buffer argument of various write syscalls.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* upstream/pvhvm:
Introduce CONFIG_XEN_PVHVM compile option
blkfront: do not create a PV cdrom device if xen_hvm_guest
support multiple .discard.* sections to avoid section type conflicts
xen/pvhvm: fix build problem when !CONFIG_XEN
xenfs: enable for HVM domains too
x86: Call HVMOP_pagetable_dying on exit_mmap.
x86: Unplug emulated disks and nics.
x86: Use xen_vcpuop_clockevent, xen_clocksource and xen wallclock.
xen: Fix find_unbound_irq in presence of ioapic irqs.
xen: Add suspend/resume support for PV on HVM guests.
xen: Xen PCI platform device driver.
x86/xen: event channels delivery on HVM.
x86: early PV on HVM features initialization.
xen: Add support for HVM hypercalls.
Conflicts:
arch/x86/xen/enlighten.c
arch/x86/xen/time.c
Use a direct per-cpu reference for the IST instead of using a scratch
register.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1280594903-6341-1-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Set the callback to receive evtchns from Xen, using the
callback vector delivery mechanism.
The traditional way for receiving event channel notifications from Xen
is via the interrupts from the platform PCI device.
The callback vector is a newer alternative that allow us to receive
notifications on any vcpu and doesn't need any PCI support: we allocate
a vector exclusively to receive events, in the vector handler we don't
need to interact with the vlapic, therefore we avoid a VMEXIT.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
In the CONFIG_AUDITSYSCALL fast-path for x86 64-bit system calls,
we can pass a bad return value and/or error indication for the
system call to audit_syscall_exit(). This happens when
TIF_NEED_RESCHED was set as the system call returned, so we went
out to schedule() and came back to the exit-audit fast-path. The
fix is to reload the user return value register from the pt_regs
before using it for audit_syscall_exit().
Both the 32-bit kernel's fast path and the 64-bit kernel's 32-bit
system call fast paths work slightly differently, so that they
always leave the fast path entirely to reschedule and don't return
there, so they don't have the analogous bugs.
Reported-by: Alexander Viro <aviro@redhat.com>
Signed-off-by: Roland McGrath <roland@redhat.com>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Fix kprobes build with non-gawk awk
x86: Split swiotlb initialization into two stages
x86: Regex support and known-movable symbols for relocs, fix _end
x86, msr: Remove incorrect, duplicated code in the MSR driver
x86: Merge kernel_thread()
x86: Sync 32/64-bit kernel_thread
x86, 32-bit: Use same regs as 64-bit for kernel_thread_helper
x86, 64-bit: Use user_mode() to determine new stack pointer in copy_thread()
x86, 64-bit: Move kernel_thread to C
x86-64, paravirt: Call set_iopl_mask() on 64 bits
x86-32: Avoid pipeline serialization in PTREGSCALL1 and 2
x86: Merge sys_clone
x86, 32-bit: Convert sys_vm86 & sys_vm86old
x86: Merge sys_sigaltstack
x86: Merge sys_execve
x86: Merge sys_iopl
x86-32: Add new pt_regs stubs
cpumask: Use modern cpumask style in arch/x86/kernel/cpu/mcheck/mce-inject.c
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (57 commits)
x86, perf events: Check if we have APIC enabled
perf_event: Fix variable initialization in other codepaths
perf kmem: Fix unused argument build warning
perf symbols: perf_header__read_build_ids() offset'n'size should be u64
perf symbols: dsos__read_build_ids() should read both user and kernel buildids
perf tools: Align long options which have no short forms
perf kmem: Show usage if no option is specified
sched: Mark sched_clock() as notrace
perf sched: Add max delay time snapshot
perf tools: Correct size given to memset
perf_event: Fix perf_swevent_hrtimer() variable initialization
perf sched: Fix for getting task's execution time
tracing/kprobes: Fix field creation's bad error handling
perf_event: Cleanup for cpu_clock_perf_event_update()
perf_event: Allocate children's perf_event_ctxp at the right time
perf_event: Clean up __perf_event_init_context()
hw-breakpoints: Modify breakpoints without unregistering them
perf probe: Update perf-probe document
perf probe: Support --del option
trace-kprobe: Support delete probe syntax
...
Prepare for merging with 32-bit.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-2-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
While dumping a stacktrace, the end of the exception stack won't link
the frame pointer to the previous stack.
The interrupted stack will then be considered as unreliable and ignored
by perf, as the frame pointer is unreliable itself.
This happens because we overwrite the frame pointer that links to the
interrupted frame with the address of the exception stack. This is
done in order to reserve space inside.
But rbp has been chosen here only because it is not a scratch register,
so that the address of the exception stack remains in rbp after calling
do_debug(), we can then release the exception stack space without the
need to retrieve its address again.
But we can pick another non-scratch register to do that, so that we
preserve the link to the interrupted stack frame in the stacktraces.
Just randomly choose r12. Every registers are saved just before and
restored just after calling do_debug(). And r12 is not used in the
middle, which makes it a perfect candidate.
Example: perf record -g -a -c 1 -f -e mem:$(tasklist_lock_addr):rw
Before:
44.18% [k] _raw_read_lock
|
|
--- |--6.31%-- waitid
|
|--4.26%-- writev
|
|--3.63%-- __select
|
|--3.15%-- __waitpid
| |
| |--28.57%-- 0x8b52e00000139f
| |
| |--28.57%-- 0x8b52e0000013c6
| |
| |--14.29%-- 0x7fde786dc000
| |
| |--14.29%-- 0x62696c2f7273752f
| |
| --14.29%-- 0x1ea9df800000000
|
|--3.00%-- __poll
After:
43.94% [k] _raw_read_lock
|
--- _read_lock
|
|--60.53%-- send_sigio
| __kill_fasync
| kill_fasync
| evdev_pass_event
| evdev_event
| input_pass_event
| input_handle_event
| input_event
| synaptics_process_byte
| psmouse_handle_byte
| psmouse_interrupt
| serio_interrupt
| i8042_interrupt
| handle_IRQ_event
| handle_edge_irq
| handle_irq
| __irqentry_text_start
| ret_from_intr
| |
| |--30.43%-- __select
| |
| |--17.39%-- 0x454f15
| |
| |--13.04%-- __read
| |
| |--13.04%-- vread_hpet
| |
| |--13.04%-- _xcb_lock_io
| |
| --13.04%-- 0x7f630878ce87
Note: it does not only affect perf events but also other stacktraces in
x86-64. They were considered as unreliable once we quit the debug
stack frame.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
include/linux/compiler-gcc4.h: Fix build bug - gcc-4.0.2 doesn't understand __builtin_object_size
x86/alternatives: No need for alternatives-asm.h to re-invent stuff already in asm.h
x86/alternatives: Check replacementlen <= instrlen at build time
x86, 64-bit: Set data segments to null after switching to 64-bit mode
x86: Clean up the loadsegment() macro
x86: Optimize loadsegment()
x86: Add missing might_fault() checks to copy_{to,from}_user()
x86-64: __copy_from_user_inatomic() adjustments
x86: Remove unused thread_return label from switch_to()
x86, 64-bit: Fix bstep_iret jump
x86: Don't use the strict copy checks when branch profiling is in use
x86, 64-bit: Move K8 B step iret fixup to fault entry asm
x86: Generate cmpxchg build failures
x86: Add a Kconfig option to turn the copy_from_user warnings into errors
x86: Turn the copy_from_user check into an (optional) compile time warning
x86: Use __builtin_memset and __builtin_memcpy for memset/memcpy
x86: Use __builtin_object_size() to validate the buffer size for copy_from_user()
This jump should be unconditional.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1257274925-15713-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Conflicts:
tools/perf/Makefile
Merge reason:
- fix the conflict
- pick up the pr_*() infrastructure to queue up dependent patch
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The function graph tracer replaces the return address with a hook
to trace the exit of the function call. This hook will finish by
returning to the real location the function should return to.
But the current implementation uses a ret to jump to the real
return location. This causes a imbalance between calls and ret.
That is the original function does a call, the ret goes to the
handler and then the handler does a ret without a matching call.
Although the function graph tracer itself still breaks the branch
predictor by replacing the original ret, by using a second ret and
causing an imbalance, it breaks the predictor even more.
This patch replaces the ret with a jmp to keep the calls and ret
balanced. I tested this on one box and it showed a 1.7% increase in
performance. Another box only showed a small 0.3% increase. But no
box that I tested this on showed a decrease in performance by
making this change.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091013203425.042034383@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Move the handling of truncated %rip from an iret fault to the fault
entry path.
This allows x86-64 to use the standard search_extable() function.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <1255357103-5418-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If TIF_SYSCALL_TRACE or TIF_SINGLESTEP is set while inside a syscall,
the path back to user mode should get to syscall_trace_leave.
This does happen in most circumstances. The exception to this is on
the 64-bit syscall fastpath, when no such flag was set on syscall
entry and nothing else has punted it off the fastpath for exit. That
one exit fastpath fails to check for _TIF_WORK_SYSCALL_EXIT flags.
This makes the behavior inconsistent with what 32-bit tasks see and
what the native 32-bit kernel always does, and what 64-bit tasks see
in all cases where the iret path is taken anyhow.
Perhaps the only example that is affected is a ptrace stop inside
do_fork (for PTRACE_O_TRACE{CLONE,FORK,VFORK,VFORKDONE}). Other
syscalls with internal ptrace stop points (execve) already take the
iret exit path for unrelated reasons.
Test cases for both PTRACE_SYSCALL and PTRACE_SINGLESTEP variants are at:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/syscall-from-clone.c?cvsroot=systemtaphttp://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/step-from-clone.c?cvsroot=systemtap
There was no special benefit to the sysret path's special path to call
do_notify_resume, because it always takes the iret exit path at the end.
So this change just makes the sysret exit path join the iret exit path
for all the signals and ptrace cases. The fastpath still applies to
the plain syscall-audit and resched cases.
Signed-off-by: Roland McGrath <roland@redhat.com>
CC: Oleg Nesterov <oleg@redhat.com>
Bye-bye Performance Counters, welcome Performance Events!
In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.
Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.
All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)
The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.
Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.
User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)
This patch has been generated via the following script:
FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')
sed -i \
-e 's/PERF_EVENT_/PERF_RECORD_/g' \
-e 's/PERF_COUNTER/PERF_EVENT/g' \
-e 's/perf_counter/perf_event/g' \
-e 's/nb_counters/nb_events/g' \
-e 's/swcounter/swevent/g' \
-e 's/tpcounter_event/tp_event/g' \
$FILES
for N in $(find . -name perf_counter.[ch]); do
M=$(echo $N | sed 's/perf_counter/perf_event/g')
mv $N $M
done
FILES=$(find . -name perf_event.*)
sed -i \
-e 's/COUNTER_MASK/REG_MASK/g' \
-e 's/COUNTER/EVENT/g' \
-e 's/\<event\>/event_id/g' \
-e 's/counter/event/g' \
-e 's/Counter/Event/g' \
$FILES
... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.
Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.
( NOTE: 'counters' are still the proper terminology when we deal
with hardware registers - and these sed scripts are a bit
over-eager in renaming them. I've undone some of that, but
in case there's something left where 'counter' would be
better than 'event' we can undo that on an individual basis
instead of touching an otherwise nicely automated patch. )
Suggested-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Only 24 bytes needs to be reserved on the stack for the function graph
tracer on x86_64.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <20090729085837.GB4998@jolsa.lab.eng.brq.redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Since nmi, debug and int3 returns to irq_return inside common_interrupt,
probing this function will cause int3-loop, so it should be marked
as __kprobes.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20090827172325.8246.40000.stgit@localhost.localdomain>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
In case gcc does something funny with the stack frames, or the return
from function code, we would like to detect that.
An arch may implement passing of a variable that is unique to the
function and can be saved on entering a function and can be tested
when exiting the function. Usually the frame pointer can be used for
this purpose.
This patch also implements this for x86. Where it passes in the stack
frame of the parent function, and will test that frame on exit.
There was a case in x86_32 with optimize for size (-Os) where, for a
few functions, gcc would align the stack frame and place a copy of the
return address into it. The function graph tracer modified the copy and
not the actual return address. On return from the funtion, it did not go
to the tracer hook, but returned to the parent. This broke the function
graph tracer, because the return of the parent (where gcc did not do
this funky manipulation) returned to the location that the child function
was suppose to. This caused strange kernel crashes.
This test detected the problem and pointed out where the issue was.
This modifies the parameters of one of the functions that the arch
specific code calls, so it includes changes to arch code to accommodate
the new prototype.
Note, I notice that the parsic arch implements its own push_return_trace.
This is now a generic function and the ftrace_push_return_trace should be
used instead. This patch does not touch that code.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (244 commits)
Revert "x86, bts: reenable ptrace branch trace support"
tracing: do not translate event helper macros in print format
ftrace/documentation: fix typo in function grapher name
tracing/events: convert block trace points to TRACE_EVENT(), fix !CONFIG_BLOCK
tracing: add protection around module events unload
tracing: add trace_seq_vprint interface
tracing: fix the block trace points print size
tracing/events: convert block trace points to TRACE_EVENT()
ring-buffer: fix ret in rb_add_time_stamp
ring-buffer: pass in lockdep class key for reader_lock
tracing: add annotation to what type of stack trace is recorded
tracing: fix multiple use of __print_flags and __print_symbolic
tracing/events: fix output format of user stack
tracing/events: fix output format of kernel stack
tracing/trace_stack: fix the number of entries in the header
ring-buffer: discard timestamps that are at the start of the buffer
ring-buffer: try to discard unneeded timestamps
ring-buffer: fix bug in ring_buffer_discard_commit
ftrace: do not profile functions when disabled
tracing: make trace pipe recognize latency format flag
...
For some time each panic() called with interrupts disabled
triggered the !irqs_disabled() WARN_ON in smp_call_function(),
producing ugly backtraces and confusing users.
This is a common situation with machine checks for example which
tend to call panic with interrupts disabled, but will also hit
in other situations e.g. panic during early boot. In fact it
means that panic cannot be called in many circumstances, which
would be bad.
This all started with the new fancy queued smp_call_function,
which is then used by the shutdown path to shut down the other
CPUs.
On closer examination it turned out that the fancy RCU
smp_call_function() does lots of things not suitable in a panic
situation anyways, like allocating memory and relying on complex
system state.
I originally tried to patch this over by checking for panic
there, but it was quite complicated and the original patch
was also not very popular. This also didn't fix some of the
underlying complexity problems.
The new code in post 2.6.29 tries to patch around this by
checking for oops_in_progress, but that is not enough to make
this fully safe and I don't think that's a real solution
because panic has to be reliable.
So instead use an own vector to reboot. This makes the reboot
code extremly straight forward, which is definitely a big plus
in a panic situation where it is important to avoid relying on
too much kernel state. The new simple code is also safe to be
called from interupts off region because it is very very simple.
There can be situations where it is important that panic
is reliable. For example on a fatal machine check the panic
is needed to get the system up again and running as quickly
as possible. So it's important that panic is reliable and
all function it calls simple.
This is why I came up with this simple vector scheme.
It's very hard to beat in simplicity. Vectors are not
particularly precious anymore since all big systems are
using per CPU vectors.
Another possibility would have been to use an NMI similar
to kdump, but there is still the problem that NMIs don't
work reliably on some systems due to BIOS issues. NMIs
would have been able to stop CPUs running with interrupts
off too. In the sake of universal reliability I opted for
using a non NMI vector for now.
I put the reboot vector into the highest priority bucket of
the APIC vectors and moved the 64bit UV_BAU message down
instead into the next lower priority.
[ Impact: bug fix, fixes an old regression ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Machine checks support waking up the mcelog daemon quickly.
The original wake up code for this was pretty ugly, relying on
a idle notifier and a special process flag. The reason it did
it this way is that the machine check handler is not subject
to normal interrupt locking rules so it's not safe
to call wake_up(). Instead it set a process flag
and then either did the wakeup in the syscall return
or in the idle notifier.
This patch adds a new "bootstraping" method as replacement.
The idea is that the handler checks if it's in a state where
it is unsafe to call wake_up(). If it's safe it calls it directly.
When it's not safe -- that is it interrupted in a critical
section with interrupts disables -- it uses a new "self IPI" to trigger
an IPI to its own CPU. This can be done safely because IPI
triggers are atomic with some care. The IPI is raised
once the interrupts are reenabled and can then safely call
wake_up().
When APICs are disabled the event is just queued and will be picked up
eventually by the next polling timer. I think that's a reasonable
compromise, since it should only happen quite rarely.
Contains fixes from Ying Huang.
[ solve conflict on irqinit, make it work on 32bit (entry_arch.h) - HS ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Remove the IRQ (non-NMI) handling bits as NMI will be used always.
Signed-off-by: Yong Wang <yong.y.wang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090603051255.GA2791@ywang-moblin2.bj.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Enable the 64bit MCE_INTEL code (CMCI, thermal interrupts) for 32bit NEW_MCE.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Allows to call different machine check handlers from the low
level machine check entry vector.
This is needed for later when it will be used for 32bit too.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Native x86-64 uses the IST mechanism to run int3 and debug traps on
an alternative stack. Xen does not do this, and so the frames were
being misinterpreted by the ptrace code. This change special-cases
these two exceptions by using Xen variants which run on the normal
kernel stack properly.
Impact: avoid crash or bad data when IST trap is invoked under Xen
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Merge reason: tracing/core was on a .30-rc1 base and was missing out on
on a handful of tracing fixes present in .30-rc5-almost.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I hit the check_flags error of lockdep:
WARNING: at kernel/lockdep.c:2893 check_flags+0x1a7/0x1d0()
[...]
hardirqs last enabled at (12567): [<ffffffff8026206a>] local_bh_enable+0xaa/0x110
hardirqs last disabled at (12569): [<ffffffff80610c76>] int3+0x16/0x40
softirqs last enabled at (12566): [<ffffffff80514d2b>] lock_sock_nested+0xfb/0x110
softirqs last disabled at (12568): [<ffffffff8058454e>] tcp_prequeue_process+0x2e/0xa0
The check_flags warning of lockdep tells me that lockdep thought interrupts
were disabled, but they were really enabled.
The numbers in the above parenthesis show the order of events:
12566: softirqs last enabled: lock_sock_nested
12567: hardirqs last enabled: local_bh_enable
12568: softirqs last disabled: tcp_prequeue_process
12566: hardirqs last disabled: int3
int3 is a breakpoint!
Examining this further, I have CONFIG_NET_TCPPROBE enabled which adds
break points into the kernel.
The paranoid_exit of the return of int3 does not account for enabling
interrupts on return to kernel. This code is a bit tricky since it
is also used by the nmi handler (when lockdep is off), and we must be
careful about the swapgs. We can not call kernel code after the swapgs
has been performed.
[ Impact: fix lockdep check_flags warning + self-turn-off ]
Acked-by: Peter Zijlsta <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: speed up
The return to handler portion of the function graph tracer should only
need to save the return values. The caller already saved off the
registers that the callee can modify. The returning function already
saved the registers it modified. When we call our own trace function
it too will save the registers that the callee must restore.
There's no reason to save off anything more that the registers used
to return the values.
Note, I did a complete kernel build with this modification and the
function graph tracer running on x86_64.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Implement set_perf_counter_pending() with a self-IPI so that it will
run ASAP in a usable context.
For now use a second IRQ vector, because the primary vector pokes
the apic in funny ways that seem to confuse things.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.724626696@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Merge reason: we have gathered quite a few conflicts, need to merge upstream
Conflicts:
arch/powerpc/kernel/Makefile
arch/x86/ia32/ia32entry.S
arch/x86/include/asm/hardirq.h
arch/x86/include/asm/unistd_32.h
arch/x86/include/asm/unistd_64.h
arch/x86/kernel/cpu/common.c
arch/x86/kernel/irq.c
arch/x86/kernel/syscall_table_32.S
arch/x86/mm/iomap_32.c
include/linux/sched.h
kernel/Makefile
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: mark save_paranoid as non-kprobe-able code
This appears to be necessary as the function gets called from
kprobes-unsafe exception handling stubs (i.e. which themselves
live in .kprobes.text).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B8F44F.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
These got left in needlessly when ret_from_fork got simplified.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B8F355.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
