x86, trace: Add page fault tracepoints
authorSeiji Aguchi <seiji.aguchi@hds.com>
Wed, 30 Oct 2013 20:39:03 +0000 (16:39 -0400)
committerH. Peter Anvin <hpa@linux.intel.com>
Fri, 8 Nov 2013 22:15:49 +0000 (14:15 -0800)
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>
arch/x86/include/asm/trace/exceptions.h [new file with mode: 0644]
arch/x86/mm/Makefile
arch/x86/mm/fault.c

diff --git a/arch/x86/include/asm/trace/exceptions.h b/arch/x86/include/asm/trace/exceptions.h
new file mode 100644 (file)
index 0000000..86540c0
--- /dev/null
@@ -0,0 +1,52 @@
+#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>
index 23d8e5fecf76ba654c3cc2fd8f9b3d3efdfa193d..6a19ad9f370d1c125ec8c3878ec49d6f80677852 100644 (file)
@@ -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
 
index fd3e281fbc70bcee0a6ddd3fad8eaef850230d20..f2730cbce0b57d7f55bc68463b0d9e26e1feeef4 100644 (file)
@@ -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);
 }