Commit b8347c21 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Ingo Molnar

x86/debug: Handle warnings before the notifier chain, to fix KGDB crash

Commit:

  9a93848f ("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: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: default avatarIlya Dryomov <idryomov@gmail.com>
Acked-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Acked-by: default avatarThomas 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.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent be739f4b
......@@ -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);
......
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