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Subject[PATCH 1/2] trace: Add trap entry/exit tracepoints
Date
From: Jiaying Zhang <jiayingz@google.com>

Add an enum for trap definitions and add entry/exit tracepoints for
traps in the system.

$ echo 1 > debug/tracing/events/trap/enable
run gdb to genrate some trap events
$ cat debug/tracing/trace
<...>-13619 [003] 917.726602: trap_entry: number=3
<...>-13619 [003] 917.726612: trap_exit: number=3
<...>-13619 [003] 917.747263: trap_entry: number=1
<...>-13619 [003] 917.747272: trap_exit: number=1
<...>-13619 [003] 917.747567: trap_entry: number=3
<...>-13619 [003] 917.747570: trap_exit: number=3
<...>-13619 [003] 917.748101: trap_entry: number=1
<...>-13619 [003] 917.748103: trap_exit: number=1
$ echo 1 > tracing_enabled; ~/trap pagefault; echo 0 > tracing_enabled
$ cat trace | grep "trap-" | grep number=14 | head
trap-12528 [003] 1159.755792: trap_entry: number=14
trap-12528 [003] 1159.755801: trap_entry: number=14
trap-12528 [003] 1159.755804: trap_entry: number=14
trap-12528 [003] 1159.755807: trap_entry: number=14
trap-12528 [003] 1159.755810: trap_entry: number=14
trap-12528 [003] 1159.755817: trap_entry: number=14
trap-12528 [003] 1159.755819: trap_entry: number=14
trap-12528 [003] 1159.755821: trap_entry: number=14
trap-12528 [003] 1159.755824: trap_entry: number=14
trap-12528 [003] 1159.755826: trap_entry: number=14
$ cat trace | grep "trap-" | grep number=7 | head
trap-12528 [003] 1159.756283: trap_entry: number=7
trap-12529 [003] 1159.757427: trap_entry: number=7
trap-12530 [003] 1159.758277: trap_entry: number=7
trap-12531 [003] 1159.759172: trap_entry: number=7
trap-12532 [003] 1159.768643: trap_entry: number=7
trap-12533 [003] 1159.778195: trap_entry: number=7
trap-15026 [001] 1557.877722: trap_entry: number=7
trap-15253 [001] 1621.395067: trap_entry: number=7
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
---
arch/x86/kernel/ptrace.c | 4 +++
arch/x86/kernel/traps.c | 16 ++++++++++++++
arch/x86/mm/fault.c | 13 ++++++++++-
include/trace/events/trap.h | 47 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 78 insertions(+), 2 deletions(-)
create mode 100644 include/trace/events/trap.h
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 45892dc..d788752 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -22,6 +22,8 @@
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>

+#include <trace/events/trap.h>
+
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@@ -1330,8 +1332,10 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
struct siginfo info;

fill_sigtrap_info(tsk, regs, error_code, si_code, &info);
+ trace_trap_entry(tsk->thread.trap_no);
/* Send us the fake SIGTRAP */
force_sig_info(SIGTRAP, &info, tsk);
+ trace_trap_exit(tsk->thread.trap_no);
}


diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 4857ff6..d450349 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -33,6 +33,9 @@
#include <linux/io.h>
#include <trace/events/irq.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/trap.h>
+
#ifdef CONFIG_EISA
#include <linux/ioport.h>
#include <linux/eisa.h>
@@ -123,6 +126,7 @@ do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
{
struct task_struct *tsk = current;

+ trace_trap_entry(trapnr);
#ifdef CONFIG_X86_32
if (regs->flags & X86_VM_MASK) {
/*
@@ -169,6 +173,7 @@ trap_signal:
force_sig_info(signr, info, tsk);
else
force_sig(signr, tsk);
+ trace_trap_exit(trapnr);
return;

kernel_trap:
@@ -177,6 +182,7 @@ kernel_trap:
tsk->thread.trap_no = trapnr;
die(str, regs, error_code);
}
+ trace_trap_exit(trapnr);
return;

#ifdef CONFIG_X86_32
@@ -184,6 +190,7 @@ vm86_trap:
if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
error_code, trapnr))
goto trap_signal;
+ trace_trap_exit(trapnr);
return;
#endif
}
@@ -286,7 +293,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
printk("\n");
}

+ trace_trap_entry(tsk->thread.trap_no);
force_sig(SIGSEGV, tsk);
+ trace_trap_exit(tsk->thread.trap_no);
return;

#ifdef CONFIG_X86_32
@@ -683,7 +692,9 @@ void math_error(struct pt_regs *regs, int error_code, int trapnr)
*/
return; /* Spurious trap, no error */
}
+ trace_trap_entry(task->thread.trap_no);
force_sig_info(SIGFPE, &info, task);
+ trace_trap_exit(task->thread.trap_no);
}

dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
@@ -704,11 +715,13 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
dotraplinkage void
do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
{
+ trace_trap_entry(15);
conditional_sti(regs);
#if 0
/* No need to warn about this any longer. */
printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
#endif
+ trace_trap_exit(15);
}

asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
@@ -780,6 +793,7 @@ EXPORT_SYMBOL_GPL(math_state_restore);
dotraplinkage void __kprobes
do_device_not_available(struct pt_regs *regs, long error_code)
{
+ trace_trap_entry(7);
#ifdef CONFIG_MATH_EMULATION
if (read_cr0() & X86_CR0_EM) {
struct math_emu_info info = { };
@@ -788,6 +802,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)

info.regs = regs;
math_emulate(&info);
+ trace_trap_exit(7);
return;
}
#endif
@@ -795,6 +810,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
#ifdef CONFIG_X86_32
conditional_sti(regs);
#endif
+ trace_trap_exit(7);
}

#ifdef CONFIG_X86_32
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 20e3f87..55bdd31 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -11,6 +11,7 @@
#include <linux/kprobes.h> /* __kprobes, ... */
#include <linux/mmiotrace.h> /* kmmio_handler, ... */
#include <linux/perf_event.h> /* perf_sw_event */
+#include <trace/events/trap.h> /* trap trace events */
#include <linux/hugetlb.h> /* hstate_index_to_shift */

#include <asm/traps.h> /* dotraplinkage, ... */
@@ -955,8 +956,8 @@ static int fault_in_kernel_space(unsigned long address)
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
-dotraplinkage void __kprobes
-do_page_fault(struct pt_regs *regs, unsigned long error_code)
+static __always_inline void
+__do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct vm_area_struct *vma;
struct task_struct *tsk;
@@ -1164,3 +1165,11 @@ good_area:

up_read(&mm->mmap_sem);
}
+
+dotraplinkage void __kprobes
+do_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+ trace_trap_entry(14);
+ __do_page_fault(regs, error_code);
+ trace_trap_exit(14);
+}
diff --git a/include/trace/events/trap.h b/include/trace/events/trap.h
new file mode 100644
index 0000000..1519b62
--- /dev/null
+++ b/include/trace/events/trap.h
@@ -0,0 +1,47 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM trap
+
+#if !defined(_TRACE_TRAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TRAP_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(trap_entry,
+
+ TP_PROTO(int id),
+
+ TP_ARGS(id),
+
+ TP_STRUCT__entry(
+ __field( int, id )
+ ),
+
+ TP_fast_assign(
+ __entry->id = id;
+ ),
+
+ TP_printk("number=%d", __entry->id)
+);
+
+TRACE_EVENT(trap_exit,
+
+ TP_PROTO(int id),
+
+ TP_ARGS(id),
+
+ TP_STRUCT__entry(
+ __field( int, id )
+ ),
+
+ TP_fast_assign(
+ __entry->id = id;
+ ),
+
+ TP_printk("number=%d", __entry->id)
+);
+
+#endif /* _TRACE_TRAP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
+
--
1.7.3.1


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