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    Subject[PATCH -tip v8 09/26] x86: Call exception_enter after kprobes handled
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    Date
    Move exception_enter() call after kprobes handler
    is done. Since the exception_enter() involves
    many other functions (like printk), it can cause
    recursive int3/break loop when kprobes probe such
    functions.

    Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    ---
    arch/x86/kernel/traps.c | 5 ++---
    1 file changed, 2 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
    index e5d4a70..ba9abe9 100644
    --- a/arch/x86/kernel/traps.c
    +++ b/arch/x86/kernel/traps.c
    @@ -327,7 +327,6 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
    if (poke_int3_handler(regs))
    return;

    - prev_state = exception_enter();
    #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
    if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
    SIGTRAP) == NOTIFY_STOP)
    @@ -338,6 +337,7 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
    if (kprobe_int3_handler(regs))
    return;
    #endif
    + prev_state = exception_enter();

    if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
    SIGTRAP) == NOTIFY_STOP)
    @@ -415,8 +415,6 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
    unsigned long dr6;
    int si_code;

    - prev_state = exception_enter();
    -
    get_debugreg(dr6, 6);

    /* Filter out all the reserved bits which are preset to 1 */
    @@ -449,6 +447,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
    if (kprobe_debug_handler(regs))
    goto exit;
    #endif
    + prev_state = exception_enter();

    if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
    SIGTRAP) == NOTIFY_STOP)



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