Messages in this thread Patch in this message | | | Date | Fri, 9 May 2014 16:07:23 +0200 | From | Oleg Nesterov <> | Subject | can't we kill DIE_GPF ? (Was: x86/traps: cleanup DO_ERROR*() to prepare for uprobes fixes) |
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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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