AuxXxilium/linux_dsm_epyc7002
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x86/entry, mce: Disallow #DB during #MC

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#MC is fragile as heck, don't tempt fate.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.131187767@infradead.org
This commit is contained in:
Peter Zijlstra 2020-05-29 23:27:35 +02:00 committed by Thomas Gleixner
parent fd338e3564
commit cd840e424f
1 changed files with 12 additions and 0 deletions
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12
arch/x86/kernel/cpu/mce/core.c
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@ -1943,22 +1943,34 @@ static __always_inline void exc_machine_check_user(struct pt_regs *regs)
/* MCE hit kernel mode */ /* MCE hit kernel mode */
DEFINE_IDTENTRY_MCE(exc_machine_check) DEFINE_IDTENTRY_MCE(exc_machine_check)
{ {
unsigned long dr7;
dr7 = local_db_save();
exc_machine_check_kernel(regs); exc_machine_check_kernel(regs);
local_db_restore(dr7);
} }
/* The user mode variant. */ /* The user mode variant. */
DEFINE_IDTENTRY_MCE_USER(exc_machine_check) DEFINE_IDTENTRY_MCE_USER(exc_machine_check)
{ {
unsigned long dr7;
dr7 = local_db_save();
exc_machine_check_user(regs); exc_machine_check_user(regs);
local_db_restore(dr7);
} }
#else #else
/* 32bit unified entry point */ /* 32bit unified entry point */
DEFINE_IDTENTRY_MCE(exc_machine_check) DEFINE_IDTENTRY_MCE(exc_machine_check)
{ {
unsigned long dr7;
dr7 = local_db_save();
if (user_mode(regs)) if (user_mode(regs))
exc_machine_check_user(regs); exc_machine_check_user(regs);
else else
exc_machine_check_kernel(regs); exc_machine_check_kernel(regs);
local_db_restore(dr7);
} }
#endif #endif