Commit 8ba62d37 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

task_work: Call tracehook_notify_signal from get_signal on all architectures 



Always handle TIF_NOTIFY_SIGNAL in get_signal.  With commit 35d0b389
("task_work: unconditionally run task_work from get_signal()") always
calling task_work_run all of the work of tracehook_notify_signal is
already happening except clearing TIF_NOTIFY_SIGNAL.

Factor clear_notify_signal out of tracehook_notify_signal and use it in
get_signal so that get_signal only needs one call of task_work_run.

To keep the semantics in sync update xfer_to_guest_mode_work (which
does not call get_signal) to call tracehook_notify_signal if either
_TIF_SIGPENDING or _TIF_NOTIFY_SIGNAL.

Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-8-ebiederm@xmission.com


Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 7f62d40d

arch/s390/kernel/signal.c

+2 −2
Original line number Diff line number Diff line
@@ -453,7 +453,7 @@ static void handle_signal(struct ksignal *ksig, sigset_t *oldset, 
 * stack-frames in one go after that.

 */



void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)

void arch_do_signal_or_restart(struct pt_regs *regs)

{

	struct ksignal ksig;

	sigset_t *oldset = sigmask_to_save();
@@ -466,7 +466,7 @@ void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal) 
	current->thread.system_call =

		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;



	if (has_signal && get_signal(&ksig)) {

	if (get_signal(&ksig)) {

		/* Whee!  Actually deliver the signal.  */

		if (current->thread.system_call) {

			regs->int_code = current->thread.system_call;

arch/x86/kernel/signal.c

+2 −2
Original line number Diff line number Diff line
@@ -861,11 +861,11 @@ static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 
 * want to handle. Thus you cannot kill init even with a SIGKILL even by

 * mistake.

 */

void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)

void arch_do_signal_or_restart(struct pt_regs *regs)

{

	struct ksignal ksig;



	if (has_signal && get_signal(&ksig)) {

	if (get_signal(&ksig)) {

		/* Whee! Actually deliver the signal.  */

		handle_signal(&ksig, regs);

		return;

include/linux/entry-common.h

+1 −1
Original line number Diff line number Diff line
@@ -257,7 +257,7 @@ static __always_inline void arch_exit_to_user_mode(void) { } 
 *

 * Invoked from exit_to_user_mode_loop().

 */

void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal);

void arch_do_signal_or_restart(struct pt_regs *regs);



/**

 * exit_to_user_mode - Fixup state when exiting to user mode

include/linux/tracehook.h

+7 −2
Original line number Diff line number Diff line
@@ -106,6 +106,12 @@ static inline void tracehook_notify_resume(struct pt_regs *regs) 
	rseq_handle_notify_resume(NULL, regs);

}



static inline void clear_notify_signal(void)

{

	clear_thread_flag(TIF_NOTIFY_SIGNAL);

	smp_mb__after_atomic();

}



/*

 * called by exit_to_user_mode_loop() if ti_work & _TIF_NOTIFY_SIGNAL. This

 * is currently used by TWA_SIGNAL based task_work, which requires breaking
@@ -113,8 +119,7 @@ static inline void tracehook_notify_resume(struct pt_regs *regs) 
 */

static inline void tracehook_notify_signal(void)

{

	clear_thread_flag(TIF_NOTIFY_SIGNAL);

	smp_mb__after_atomic();

	clear_notify_signal();

	if (task_work_pending(current))

		task_work_run();

}

kernel/entry/common.c

+2 −10
Original line number Diff line number Diff line
@@ -139,15 +139,7 @@ void noinstr exit_to_user_mode(void) 
}



/* Workaround to allow gradual conversion of architecture code */

void __weak arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal) { }



static void handle_signal_work(struct pt_regs *regs, unsigned long ti_work)

{

	if (ti_work & _TIF_NOTIFY_SIGNAL)

		tracehook_notify_signal();



	arch_do_signal_or_restart(regs, ti_work & _TIF_SIGPENDING);

}

void __weak arch_do_signal_or_restart(struct pt_regs *regs) { }



static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,

					    unsigned long ti_work)
@@ -170,7 +162,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, 
			klp_update_patch_state(current);



		if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))

			handle_signal_work(regs, ti_work);

			arch_do_signal_or_restart(regs);



		if (ti_work & _TIF_NOTIFY_RESUME)

			tracehook_notify_resume(regs);