Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends. That changed
when we forked out support for the latter into the export.h file.
This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig. The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.
Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each obj-y/bool instance
for the presence of either and replace accordingly where needed.
Note that some bool/obj-y instances remain since module.h is
the header for some exception table entry stuff, and for things
like __init_or_module (code that is tossed when MODULES=n).
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160714001901.31603-3-paul.gortmaker@windriver.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Kmemcheck should use the preferred interface for parsing command line
arguments, kstrto*(), rather than sscanf() itself. Use it
appropriately.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In x86, faults exit by executing the iret instruction, which then
reenables NMIs if we faulted in NMI context. Then if a fault
happens in NMI, another NMI can nest after the fault exits.
But we don't yet support nested NMIs because we have only one NMI
stack. To prevent from that, check that vmalloc and kmemcheck
faults don't happen in this context. Most of the other kernel faults
in NMIs can be more easily spotted by finding explicit
copy_from,to_user() calls on review.
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: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
This is a fix for bug #14845 (bugzilla.kernel.org). The update_checksum()
function in mm/kmemleak.c calls kmemcheck_is_obj_initialised() before scanning
an object. When KMEMCHECK_PARTIAL_OK is enabled, this function returns true.
However, the crc32_le() reads smaller intervals (32-bit) for which
kmemleak_is_obj_initialised() may be false leading to a kmemcheck warning.
Note that kmemcheck_is_obj_initialized() is currently only used by
kmemleak before scanning a memory location.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christian Casteyde <casteyde.christian@free.fr>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Ingo Molnar reported the following kmemcheck warning when running both
kmemleak and kmemcheck enabled:
PM: Adding info for No Bus:vcsa7
WARNING: kmemcheck: Caught 32-bit read from uninitialized memory
(f6f6e1a4)
d873f9f600000000c42ae4c1005c87f70000000070665f666978656400000000
i i i i u u u u i i i i i i i i i i i i i i i i i i i i i u u u
^
Pid: 3091, comm: kmemleak Not tainted (2.6.31-rc7-tip #1303) P4DC6
EIP: 0060:[<c110301f>] EFLAGS: 00010006 CPU: 0
EIP is at scan_block+0x3f/0xe0
EAX: f40bd700 EBX: f40bd780 ECX: f16b46c0 EDX: 00000001
ESI: f6f6e1a4 EDI: 00000000 EBP: f10f3f4c ESP: c2605fcc
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
CR0: 8005003b CR2: e89a4844 CR3: 30ff1000 CR4: 000006f0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff4ff0 DR7: 00000400
[<c110313c>] scan_object+0x7c/0xf0
[<c1103389>] kmemleak_scan+0x1d9/0x400
[<c1103a3c>] kmemleak_scan_thread+0x4c/0xb0
[<c10819d4>] kthread+0x74/0x80
[<c10257db>] kernel_thread_helper+0x7/0x3c
[<ffffffff>] 0xffffffff
kmemleak: 515 new suspected memory leaks (see
/sys/kernel/debug/kmemleak)
kmemleak: 42 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
The problem here is that kmemleak will scan partially initialized
objects that makes kmemcheck complain. Fix that up by skipping
uninitialized memory regions when kmemcheck is enabled.
Reported-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This check is a left-over from ancient times. We now have the equivalent
check much earlier in both the page fault handler and the debug trap
handler (the calls to kmemcheck_active()).
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
We've had some troubles in the past with weird instructions. This
patch adds a self-test framework which can be used to verify that
a certain set of opcodes are decoded correctly. Of course, the
opcodes which are not tested can still give the wrong results.
In short, this is just a safeguard to catch unintentional changes
in the opcode decoder. It does not mean that errors can't still
occur!
[rebased for mainline inclusion]
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Lets use kmemcheck_pte_lookup() in kmemcheck_fault() instead of
open-coding it there.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Multiple ifdef'd definitions of the same global variable is ugly and
error-prone. Fix that up.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
The "Bugs, beware!" printout during is cute but confuses users that something
bad happened so change the text to the more boring "Initialized" message.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
General description: kmemcheck is a patch to the linux kernel that
detects use of uninitialized memory. It does this by trapping every
read and write to memory that was allocated dynamically (e.g. using
kmalloc()). If a memory address is read that has not previously been
written to, a message is printed to the kernel log.
Thanks to Andi Kleen for the set_memory_4k() solution.
Andrew Morton suggested documenting the shadow member of struct page.
Signed-off-by: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
[export kmemcheck_mark_initialized]
[build fix for setup_max_cpus]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[rebased for mainline inclusion]
Signed-off-by: Vegard Nossum <vegardno@ifi.uio.no>
