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x86, trace: Add page fault tracepoints

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This patch introduces page fault tracepoints to x86 architecture
by switching IDT.

  Two events, for user and kernel spaces, are introduced at the beginning
  of page fault handler for tracing.

  - User space event
    There is a request of page fault event for user space as below.

    https://lkml.kernel.org/r/1368079520-11015-2-git-send-email-fdeslaur+()+gmail+!+com
    https://lkml.kernel.org/r/1368079520-11015-1-git-send-email-fdeslaur+()+gmail+!+com

  - Kernel space event:
    When we measure an overhead in kernel space for investigating performance
    issues, we can check if it comes from the page fault events.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/52716E67.6090705@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Seiji Aguchi
2013-10-30 16:39:03 -04:00
committed by H. Peter Anvin
parent ac7956e269
commit d34603b07c
3 changed files with 67 additions and 0 deletions
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13
arch/x86/mm/fault.c
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@@ -20,6 +20,9 @@
#include <asm/kmemcheck.h> /* kmemcheck_*(), ... */
#include <asm/fixmap.h> /* VSYSCALL_START */
#define CREATE_TRACE_POINTS
#include <asm/trace/exceptions.h>
/*
* Page fault error code bits:
*
@@ -1232,12 +1235,22 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
exception_exit(prev_state);
}
static void trace_page_fault_entries(struct pt_regs *regs,
unsigned long error_code)
{
if (user_mode(regs))
trace_user_page_fault(read_cr2(), regs, error_code);
else
trace_kernel_page_fault(read_cr2(), regs, error_code);
}
dotraplinkage void __kprobes
trace_do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
enum ctx_state prev_state;
prev_state = exception_enter();
trace_page_fault_entries(regs, error_code);
__do_page_fault(regs, error_code);
exception_exit(prev_state);
}