Commit d34603b0 authored by Seiji Aguchi's avatar Seiji Aguchi Committed by H. Peter Anvin
Browse files

x86, trace: Add page fault tracepoints 

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: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/52716E67.6090705@hds.com


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent ac7956e2

arch/x86/include/asm/trace/exceptions.h

0 → 100644
+52 −0
Original line number Diff line number Diff line 
#undef TRACE_SYSTEM

#define TRACE_SYSTEM exceptions



#if !defined(_TRACE_PAGE_FAULT_H) || defined(TRACE_HEADER_MULTI_READ)

#define _TRACE_PAGE_FAULT_H



#include <linux/tracepoint.h>



extern void trace_irq_vector_regfunc(void);

extern void trace_irq_vector_unregfunc(void);



DECLARE_EVENT_CLASS(x86_exceptions,



	TP_PROTO(unsigned long address, struct pt_regs *regs,

		 unsigned long error_code),



	TP_ARGS(address, regs, error_code),



	TP_STRUCT__entry(

		__field(		unsigned long, address	)

		__field(		unsigned long, ip	)

		__field(		unsigned long, error_code )

	),



	TP_fast_assign(

		__entry->address = address;

		__entry->ip = regs->ip;

		__entry->error_code = error_code;

	),



	TP_printk("address=%pf ip=%pf error_code=0x%lx",

		  (void *)__entry->address, (void *)__entry->ip,

		  __entry->error_code) );



#define DEFINE_PAGE_FAULT_EVENT(name)				\

DEFINE_EVENT_FN(x86_exceptions, name,				\

	TP_PROTO(unsigned long address,	struct pt_regs *regs,	\

		 unsigned long error_code),			\

	TP_ARGS(address, regs, error_code),			\

	trace_irq_vector_regfunc,				\

	trace_irq_vector_unregfunc);



DEFINE_PAGE_FAULT_EVENT(user_page_fault);

DEFINE_PAGE_FAULT_EVENT(kernel_page_fault);



#undef TRACE_INCLUDE_PATH

#define TRACE_INCLUDE_PATH .

#define TRACE_INCLUDE_FILE exceptions

#endif /*  _TRACE_PAGE_FAULT_H */



/* This part must be outside protection */

#include <trace/define_trace.h>

arch/x86/mm/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ nostackp := $(call cc-option, -fno-stack-protector) 
CFLAGS_physaddr.o		:= $(nostackp)

CFLAGS_setup_nx.o		:= $(nostackp)



CFLAGS_fault.o := -I$(src)/../include/asm/trace



obj-$(CONFIG_X86_PAT)		+= pat_rbtree.o

obj-$(CONFIG_SMP)		+= tlb.o

arch/x86/mm/fault.c

+13 −0
Original line number Diff line number Diff line
@@ -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);

}

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