diff options
| author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2017-07-24 13:04:28 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-11-10 08:04:19 +0100 |
| commit | b8347c2196492f4e1cccde3d92fda1cc2cc7de7e (patch) | |
| tree | 5de43435f937ffaa8ea5525517c5aef848faf2bb | |
| parent | be739f4b5ddece74ef25e2304b17a7fd24575e9b (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>
| -rw-r--r-- | arch/x86/kernel/traps.c | 10 |
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); |