path: root/arch/x86/kernel/traps.c
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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2017-07-24 13:04:28 +0300
committerIngo Molnar <mingo@kernel.org>2017-11-10 08:04:19 +0100
commitb8347c2196492f4e1cccde3d92fda1cc2cc7de7e (patch)
tree5de43435f937ffaa8ea5525517c5aef848faf2bb /arch/x86/kernel/traps.c
parentbe739f4b5ddece74ef25e2304b17a7fd24575e9b (diff)
x86/debug: Handle warnings before the notifier chain, to fix KGDB crash
Commit: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") turned warnings into UD0, but the fixup code only runs after the notify_die() chain. This is a problem, in particular, with kgdb, which kicks in as if it was a BUG(). Fix this by running the fixup code before the notifier chain in the invalid op handler path. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Tested-by: Ilya Dryomov <idryomov@gmail.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard.weinberger@gmail.com> Cc: <stable@vger.kernel.org> # v4.12+ Link: http://lkml.kernel.org/r/20170724100428.19173-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/traps.c')
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 67db4f43309e..5a6b8f809792 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -209,9 +209,6 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
if (fixup_exception(regs, trapnr))
return 0;
- if (fixup_bug(regs, trapnr))
- return 0;
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = trapnr;
die(str, regs, error_code);
@@ -292,6 +289,13 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
+ /*
+ * WARN*()s end up here; fix them up before we call the
+ * notifier chain.
+ */
+ if (!user_mode(regs) && fixup_bug(regs, trapnr))
+ return;
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=

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