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linux-next/arch/x86_64
Andi Kleen daeeafecf0 [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>
2005-04-16 15:25:13 -07:00
..
boot Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ia32 [PATCH] x86_64: Use a VMA for the 32bit vsyscall 2005-04-16 15:24:55 -07:00
kernel [PATCH] x86_64: Keep only a single debug notifier chain 2005-04-16 15:25:13 -07:00
lib Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mm [PATCH] x86_64: Use a common function to find code segment bases 2005-04-16 15:24:59 -07:00
oprofile Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pci Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
defconfig Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Kconfig Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Kconfig.debug Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Makefile Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00