On 05/08, Oleg Nesterov wrote:
>
> For example, after this series
> we can convert math_error() into the "normal" DO_ERROR() user, and most
> probably
> we can do the same with do_general_protection().
As for do_general_protection(), the problem is DIE_GPF.
Masami, could you explain why it is needed ? kprobe_exceptions_notify()
is the only user, can't it use DIE_TRAP and check trapnr = X86_TRAP_GP ?
And if it can, probably we can do notify_die() at the start like other
DO_ERROR() functions do ?
IOW, any reason why the patch below is wrong?
Oleg.
--- x/arch/x86/include/asm/kdebug.h
+++ x/arch/x86/include/asm/kdebug.h
@@ -15,7 +15,6 @@ enum die_val {
DIE_DIE,
DIE_KERNELDEBUG,
DIE_TRAP,
- DIE_GPF,
DIE_CALL,
DIE_PAGE_FAULT,
DIE_NMIUNKNOWN,
--- x/arch/x86/kernel/traps.c
+++ x/arch/x86/kernel/traps.c
@@ -283,6 +283,9 @@ do_general_protection(struct pt_regs *re
enum ctx_state prev_state;
prev_state = exception_enter();
+ if (notify_die(DIE_TRAP, "general protection fault", regs, error_code,
+ X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP)
+ goto exit;
conditional_sti(regs);
#ifdef CONFIG_X86_32
@@ -300,10 +303,7 @@ do_general_protection(struct pt_regs *re
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
- if (notify_die(DIE_GPF, "general protection fault", regs,
error_code,
- X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
- die("general protection fault", regs, error_code);
- goto exit;
+ die("general protection fault", regs, error_code);
}
tsk->thread.error_code = error_code;
--- x/arch/x86/kernel/kprobes/core.c
+++ x/arch/x86/kernel/kprobes/core.c
@@ -979,13 +979,14 @@ kprobe_exceptions_notify(struct notifier
ret = NOTIFY_STOP;
}
break;
- case DIE_GPF:
+ case DIE_TRAP:
/*
* To be potentially processing a kprobe fault and to
* trust the result from kprobe_running(), we have
* be non-preemptible.
*/
- if (!preemptible() && kprobe_running() &&
+ if (args->trapnr == X86_TRAP_GP &&
+ !preemptible() && kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
break;
--
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