4.13-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Shishkin alexander.shishkin@linux.intel.com
commit b8347c2196492f4e1cccde3d92fda1cc2cc7de7e upstream.
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 Link: http://lkml.kernel.org/r/20170724100428.19173-1-alexander.shishkin@linux.int... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/traps.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -221,9 +221,6 @@ do_trap_no_signal(struct task_struct *ts 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); @@ -304,6 +301,13 @@ static void do_error_trap(struct pt_regs
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);