Commit 8d5ea35c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/entry: Consolidate check_user_regs() 



The user register sanity check is sprinkled all over the place. Move it
into enter_from_user_mode().

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200722220519.943016204@linutronix.de
parent b35ad840

arch/x86/entry/common.c

+9 −15
Original line number Diff line number Diff line
@@ -82,10 +82,11 @@ static noinstr void check_user_regs(struct pt_regs *regs) 
 * 2) Invoke context tracking if enabled to reactivate RCU

 * 3) Trace interrupts off state

 */

static noinstr void enter_from_user_mode(void)

static noinstr void enter_from_user_mode(struct pt_regs *regs)

{

	enum ctx_state state = ct_state();



	check_user_regs(regs);

	lockdep_hardirqs_off(CALLER_ADDR0);

	user_exit_irqoff();
@@ -95,8 +96,9 @@ static noinstr void enter_from_user_mode(void) 
	instrumentation_end();

}

#else

static __always_inline void enter_from_user_mode(void)

static __always_inline void enter_from_user_mode(struct pt_regs *regs)

{

	check_user_regs(regs);

	lockdep_hardirqs_off(CALLER_ADDR0);

	instrumentation_begin();

	trace_hardirqs_off_finish();
@@ -369,9 +371,7 @@ __visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs) 
{

	struct thread_info *ti;



	check_user_regs(regs);



	enter_from_user_mode();

	enter_from_user_mode(regs);

	instrumentation_begin();



	local_irq_enable();
@@ -434,9 +434,7 @@ static void do_syscall_32_irqs_on(struct pt_regs *regs) 
/* Handles int $0x80 */

__visible noinstr void do_int80_syscall_32(struct pt_regs *regs)

{

	check_user_regs(regs);



	enter_from_user_mode();

	enter_from_user_mode(regs);

	instrumentation_begin();



	local_irq_enable();
@@ -487,8 +485,6 @@ __visible noinstr long do_fast_syscall_32(struct pt_regs *regs) 
					vdso_image_32.sym_int80_landing_pad;

	bool success;



	check_user_regs(regs);



	/*

	 * SYSENTER loses EIP, and even SYSCALL32 needs us to skip forward

	 * so that 'regs->ip -= 2' lands back on an int $0x80 instruction.
@@ -496,7 +492,7 @@ __visible noinstr long do_fast_syscall_32(struct pt_regs *regs) 
	 */

	regs->ip = landing_pad;



	enter_from_user_mode();

	enter_from_user_mode(regs);

	instrumentation_begin();



	local_irq_enable();
@@ -599,8 +595,7 @@ idtentry_state_t noinstr idtentry_enter(struct pt_regs *regs) 
	};



	if (user_mode(regs)) {

		check_user_regs(regs);

		enter_from_user_mode();

		enter_from_user_mode(regs);

		return ret;

	}
@@ -733,8 +728,7 @@ void noinstr idtentry_exit(struct pt_regs *regs, idtentry_state_t state) 
 */

void noinstr idtentry_enter_user(struct pt_regs *regs)

{

	check_user_regs(regs);

	enter_from_user_mode();

	enter_from_user_mode(regs);

}



/**

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