x86/entry, mce: Disallow #DB during #MC (cd840e42) · Commits · 戴 / test

#MC is fragile as heck, don't tempt fate. Signed-off-by:

arch/x86/kernel/cpu/mce/core.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -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