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authorAlexander Shishkin <[email protected]>2017-07-24 13:04:28 +0300
committerIngo Molnar <[email protected]>2017-11-10 08:04:19 +0100
commitb8347c2196492f4e1cccde3d92fda1cc2cc7de7e (patch)
tree5de43435f937ffaa8ea5525517c5aef848faf2bb
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 <[email protected]> Tested-by: Ilya Dryomov <[email protected]> Acked-by: Daniel Thompson <[email protected]> Acked-by: Thomas Gleixner <[email protected]> Cc: Jason Wessel <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Richard Weinberger <[email protected]> Cc: <[email protected]> # v4.12+ Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
-rw-r--r--arch/x86/kernel/traps.c10
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) !=
NOTIFY_STOP) {
cond_local_irq_enable(regs);