From cd840e424f27fcc1ae8d14b7ec3ec4560ee6561a Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 29 May 2020 23:27:35 +0200 Subject: [PATCH] x86/entry, mce: Disallow #DB during #MC #MC is fragile as heck, don't tempt fate. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200529213321.131187767@infradead.org --- arch/x86/kernel/cpu/mce/core.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 068e6cab1286..be499267bbb4 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1943,22 +1943,34 @@ static __always_inline void exc_machine_check_user(struct pt_regs *regs) /* MCE hit kernel mode */ DEFINE_IDTENTRY_MCE(exc_machine_check) { + unsigned long dr7; + + dr7 = local_db_save(); exc_machine_check_kernel(regs); + local_db_restore(dr7); } /* The user mode variant. */ DEFINE_IDTENTRY_MCE_USER(exc_machine_check) { + unsigned long dr7; + + dr7 = local_db_save(); exc_machine_check_user(regs); + local_db_restore(dr7); } #else /* 32bit unified entry point */ DEFINE_IDTENTRY_MCE(exc_machine_check) { + unsigned long dr7; + + dr7 = local_db_save(); if (user_mode(regs)) exc_machine_check_user(regs); else exc_machine_check_kernel(regs); + local_db_restore(dr7); } #endif -- 2.39.5