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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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