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

#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

View File

@ -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