diff options
| author | Siarhei Liakh <Siarhei.Liakh@concurrent-rt.com> | 2018-06-14 19:36:07 +0000 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-06-20 11:44:56 +0200 |
| commit | 3ae6295ccb7cf6d344908209701badbbbb503e40 (patch) | |
| tree | 8c78733ff8b5fc228c089deb4002e90b70e6f781 | |
| parent | 1d9f3e20a56d33e55748552aeec597f58542f92d (diff) | |
x86: Call fixup_exception() before notify_die() in math_error()
fpu__drop() has an explicit fwait which under some conditions can trigger a
fixable FPU exception while in kernel. Thus, we should attempt to fixup the
exception first, and only call notify_die() if the fixup failed just like
in do_general_protection(). The original call sequence incorrectly triggers
KDB entry on debug kernels under particular FPU-intensive workloads.
Andy noted, that this makes the whole conditional irq enable thing even
more inconsistent, but fixing that it outside the scope of this.
Signed-off-by: Siarhei Liakh <siarhei.liakh@concurrent-rt.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Borislav Petkov" <bpetkov@suse.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/DM5PR11MB201156F1CAB2592B07C79A03B17D0@DM5PR11MB2011.namprd11.prod.outlook.com
| -rw-r--r-- | arch/x86/kernel/traps.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 03f3d7695dac..162a31d80ad5 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -834,16 +834,18 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr) char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" : "simd exception"; - if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP) - return; cond_local_irq_enable(regs); if (!user_mode(regs)) { - if (!fixup_exception(regs, trapnr)) { - task->thread.error_code = error_code; - task->thread.trap_nr = trapnr; + if (fixup_exception(regs, trapnr)) + return; + + task->thread.error_code = error_code; + task->thread.trap_nr = trapnr; + + if (notify_die(DIE_TRAP, str, regs, error_code, + trapnr, SIGFPE) != NOTIFY_STOP) die(str, regs, error_code); - } return; } |