[patch V4 06/15] x86/entry: Consolidate check_user_regs()

Thomas Gleixner
2020-07-21T11:09:57Z

From: Thomas Gleixner <tglx@linutronix.de>

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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/x86/entry/common.c | 24 +++++++++---------------
1 file changed, 9 insertions(+), 15 deletions(-)

--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -82,10 +82,11 @@ static noinstr void check_user_regs(stru
* 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
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 @@ static void __syscall_return_slowpath(st
{
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
/* 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 @@ static bool __do_fast_syscall_32(struct
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 @@ static bool __do_fast_syscall_32(struct
*/
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(
};

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_reg
*/
void noinstr idtentry_enter_user(struct pt_regs *regs)
{
- check_user_regs(regs);
- enter_from_user_mode();
+ enter_from_user_mode(regs);
}

/**