Commit-ID: 9414e99672271adcc661f3c160a30b374179b92f
Gitweb: http://git.kernel.org/tip/9414e99672271adcc661f3c160a30b374179b92f
Author: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx>
AuthorDate: Wed, 28 Apr 2010 12:09:16 -0500
Committer: Robert Richter <robert.richter@xxxxxxx>
CommitDate: Mon, 3 May 2010 23:02:39 +0200
oprofile: protect from not being in an IRQ context
http://lkml.org/lkml/2010/4/27/285
Protect against dereferencing regs when it's NULL, and
force a magic number into pc to prevent too deep processing.
This approach permits the dropped samples to be tallied as
invalid Instruction Pointer events.
e.g. output from about 15mins at 10kHz sample rate:
Nr. samples received: 2565380
Nr. samples lost invalid pc: 4
Signed-off-by: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx>
Signed-off-by: Robert Richter <robert.richter@xxxxxxx>
---
drivers/oprofile/cpu_buffer.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 0ac8b06..219f79e 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -319,8 +319,16 @@ void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
{
- int is_kernel = !user_mode(regs);
- unsigned long pc = profile_pc(regs);
+ int is_kernel;
+ unsigned long pc;
+
+ if (likely(regs)) {
+ is_kernel = !user_mode(regs);
+ pc = profile_pc(regs);
+ } else {
+ is_kernel = 0; /* This value will not be used */
+ pc = ESCAPE_CODE; /* as this causes an early return. */
+ }
__oprofile_add_ext_sample(pc, regs, event, is_kernel);
}
--
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