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authorAndi Kleen <ak@suse.de>2005-04-16 15:25:13 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:25:13 -0700
commitdaeeafecf029a05a304fa299706b3ecc90e16175 (patch)
tree7b17fd7408b47892e391604c6791674f03109e1c /arch/x86_64
parentece90303ec7e2e8d8610eb03ee7648755dd8efe7 (diff)
[PATCH] x86_64: Keep only a single debug notifier chain
Calling a notifier three times in the debug handler does not make much sense, because a debugger can figure out the various conditions by itself. Remove the additional calls to DIE_DEBUG and DIE_DEBUGSTEP completely. This matches what i386 does now. This also makes sure interrupts are always still disabled when calling a debugger, which prevents: BUG: using smp_processor_id() in preemptible [00000001] code: tpopf/1470 caller is post_kprobe_handler+0x9/0x70 Call Trace:<ffffffff8024f10f>{smp_processor_id+191} <ffffffff80120e69>{post_kpro be_handler+9} <ffffffff80120f7a>{kprobe_exceptions_notify+58} <ffffffff80144fc0>{notifier_call_chain+32} <ffffffff80110daf>{do_debug+335} <ffffffff8010f513>{debug+127} <EOE> on preemptible debug kernels with kprobes when single stepping in user space. This was probably a bug even on non preempt kernels, this function was supposed to be running with interrupts off according to a comment there. Note to third part debugger maintainers: please double check your debugger can still single step. Cc: <prasanna@in.ibm.com> Cc: <jbeulich@novell.com> Cc: <kaos@sgi.com> Cc: <jim.houston@ccur.com> Cc: <jfv@bluesong.net> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/x86_64')
-rw-r--r--arch/x86_64/kernel/traps.c14
1 files changed, 3 insertions, 11 deletions
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 2f42fd5c075f..f6ccf155e3e5 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -659,9 +659,9 @@ asmlinkage void do_debug(struct pt_regs * regs, unsigned long error_code)
asm("movq %%db6,%0" : "=r" (condition));
if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
- SIGTRAP) == NOTIFY_STOP) {
+ SIGTRAP) == NOTIFY_STOP)
return;
- }
+
conditional_sti(regs);
/* Mask out spurious debug traps due to lazy DR7 setting */
@@ -674,9 +674,7 @@ asmlinkage void do_debug(struct pt_regs * regs, unsigned long error_code)
tsk->thread.debugreg6 = condition;
/* Mask out spurious TF errors due to lazy TF clearing */
- if ((condition & DR_STEP) &&
- (notify_die(DIE_DEBUGSTEP, "debugstep", regs, condition,
- 1, SIGTRAP) != NOTIFY_STOP)) {
+ if (condition & DR_STEP) {
/*
* The TF error should be masked out only if the current
* process is not traced and if the TRAP flag has been set
@@ -711,16 +709,10 @@ asmlinkage void do_debug(struct pt_regs * regs, unsigned long error_code)
force_sig_info(SIGTRAP, &info, tsk);
clear_dr7:
asm volatile("movq %0,%%db7"::"r"(0UL));
- notify_die(DIE_DEBUG, "debug", regs, condition, 1, SIGTRAP);
return;
clear_TF_reenable:
set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
-
-clear_TF:
- /* RED-PEN could cause spurious errors */
- if (notify_die(DIE_DEBUG, "debug2", regs, condition, 1, SIGTRAP)
- != NOTIFY_STOP)
regs->eflags &= ~TF_MASK;
}