x86/entry: Implement user mode C entry points for #DB and #MCE (4c0dcd83) · Commits · 戴 / test

arch/x86/entry/entry_64.S

+1 −1

Original line number	Diff line number	Diff line
		@@ -657,7 +657,7 @@ SYM_CODE_START(\asmsym)

		/* Switch to the regular task stack and use the noist entry point */
		.Lfrom_usermode_switch_stack_\@:
		idtentry_body vector \cfunc, has_error_code=0
		idtentry_body vector noist_\cfunc, has_error_code=0 sane=1

		_ASM_NOKPROBE(\asmsym)
		SYM_CODE_END(\asmsym)

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

+33 −7

Original line number	Diff line number	Diff line
		@@ -1904,24 +1904,50 @@ static void unexpected_machine_check(struct pt_regs *regs)
		/* Call the installed machine check handler for this CPU setup. */
		void (machine_check_vector)(struct pt_regs ) = unexpected_machine_check;

		DEFINE_IDTENTRY_MCE(exc_machine_check)
		static __always_inline void exc_machine_check_kernel(struct pt_regs *regs)
		{
		/*
		* Only required when from kernel mode. See
		* mce_check_crashing_cpu() for details.
		*/
		if (machine_check_vector == do_machine_check &&
		mce_check_crashing_cpu())
		return;

		if (user_mode(regs))
		idtentry_enter(regs);
		else
		nmi_enter();
		machine_check_vector(regs);
		nmi_exit();
		}

		static __always_inline void exc_machine_check_user(struct pt_regs *regs)
		{
		idtentry_enter(regs);
		machine_check_vector(regs);
		idtentry_exit(regs);
		}

		#ifdef CONFIG_X86_64
		/* MCE hit kernel mode */
		DEFINE_IDTENTRY_MCE(exc_machine_check)
		{
		exc_machine_check_kernel(regs);
		}

		/* The user mode variant. */
		DEFINE_IDTENTRY_MCE_USER(exc_machine_check)
		{
		exc_machine_check_user(regs);
		}
		#else
		/* 32bit unified entry point */
		DEFINE_IDTENTRY_MCE(exc_machine_check)
		{
		if (user_mode(regs))
		idtentry_exit(regs);
		exc_machine_check_user(regs);
		else
		nmi_exit();
		exc_machine_check_kernel(regs);
		}
		#endif

		/*
		* Called for each booted CPU to set up machine checks.

arch/x86/kernel/traps.c

+54 −16

Original line number	Diff line number	Diff line
		@@ -775,20 +775,12 @@ static __always_inline void debug_exit(unsigned long dr7)
		*
		* May run on IST stack.
		*/
		DEFINE_IDTENTRY_DEBUG(exc_debug)
		static noinstr void handle_debug(struct pt_regs *regs, unsigned long dr6)
		{
		struct task_struct *tsk = current;
		unsigned long dr6, dr7;
		int user_icebp = 0;
		int si_code;

		debug_enter(&dr6, &dr7);

		if (user_mode(regs))
		idtentry_enter(regs);
		else
		nmi_enter();

		/*
		* The SDM says "The processor clears the BTF flag when it
		* generates a debug exception." Clear TIF_BLOCKSTEP to keep
		@@ -800,7 +792,7 @@ DEFINE_IDTENTRY_DEBUG(exc_debug)
		is_sysenter_singlestep(regs))) {
		dr6 &= ~DR_STEP;
		if (!dr6)
		goto exit;
		return;
		/*
		* else we might have gotten a single-step trap and hit a
		* watchpoint at the same time, in which case we should fall
		@@ -821,12 +813,12 @@ DEFINE_IDTENTRY_DEBUG(exc_debug)

		#ifdef CONFIG_KPROBES
		if (kprobe_debug_handler(regs))
		goto exit;
		return;
		#endif

		if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, 0,
		SIGTRAP) == NOTIFY_STOP)
		goto exit;
		return;

		/*
		* Let others (NMI) know that the debug stack is in use
		@@ -842,7 +834,7 @@ DEFINE_IDTENTRY_DEBUG(exc_debug)
		X86_TRAP_DB);
		cond_local_irq_disable(regs);
		debug_stack_usage_dec();
		goto exit;
		return;
		}

		if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
		@@ -861,14 +853,60 @@ DEFINE_IDTENTRY_DEBUG(exc_debug)
		send_sigtrap(regs, 0, si_code);
		cond_local_irq_disable(regs);
		debug_stack_usage_dec();
		}

		exit:
		if (user_mode(regs))
		static __always_inline void exc_debug_kernel(struct pt_regs *regs,
		unsigned long dr6)
		{
		nmi_enter();
		handle_debug(regs, dr6);
		nmi_exit();
		}

		static __always_inline void exc_debug_user(struct pt_regs *regs,
		unsigned long dr6)
		{
		idtentry_enter(regs);
		handle_debug(regs, dr6);
		idtentry_exit(regs);
		}

		#ifdef CONFIG_X86_64
		/* IST stack entry */
		DEFINE_IDTENTRY_DEBUG(exc_debug)
		{
		unsigned long dr6, dr7;

		debug_enter(&dr6, &dr7);
		exc_debug_kernel(regs, dr6);
		debug_exit(dr7);
		}

		/* User entry, runs on regular task stack */
		DEFINE_IDTENTRY_DEBUG_USER(exc_debug)
		{
		unsigned long dr6, dr7;

		debug_enter(&dr6, &dr7);
		exc_debug_user(regs, dr6);
		debug_exit(dr7);
		}
		#else
		/* 32 bit does not have separate entry points. */
		DEFINE_IDTENTRY_DEBUG(exc_debug)
		{
		unsigned long dr6, dr7;

		debug_enter(&dr6, &dr7);

		if (user_mode(regs))
		exc_debug_user(regs, dr6);
		else
		nmi_exit();
		exc_debug_kernel(regs, dr6);

		debug_exit(dr7);
		}
		#endif

		/*
		* Note that we play around with the 'TS' bit in an attempt to get

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