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task_work: Call tracehook_notify_signal from get_signal on all architectures

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Always handle TIF_NOTIFY_SIGNAL in get_signal.  With commit 35d0b389f3
("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: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-8-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2022-02-09 09:51:14 -06:00
parent 7f62d40d9c
commit 8ba62d3794
7 changed files with 18 additions and 29 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
arch/s390/kernel/signal.c
View file

@ -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;

4
arch/x86/kernel/signal.c
View file

@ -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;

2
include/linux/entry-common.h
View file

@ -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

9
include/linux/tracehook.h
View file

@ -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();
}

12
kernel/entry/common.c
View file

@ -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);

2
kernel/entry/kvm.c
View file

@ -8,7 +8,7 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
do {
int ret;
if (ti_work & _TIF_NOTIFY_SIGNAL)
if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
tracehook_notify_signal();
if (ti_work & _TIF_SIGPENDING) {

14
kernel/signal.c
View file

@ -2626,20 +2626,12 @@ bool get_signal(struct ksignal *ksig)
struct signal_struct *signal = current->signal;
int signr;
clear_notify_signal();
if (unlikely(task_work_pending(current)))
task_work_run();
/*
* For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
* that the arch handlers don't all have to do it. If we get here
* without TIF_SIGPENDING, just exit after running signal work.
*/
if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
if (test_thread_flag(TIF_NOTIFY_SIGNAL))
tracehook_notify_signal();
if (!task_sigpending(current))
return false;
}
if (!task_sigpending(current))
return false;
if (unlikely(uprobe_deny_signal()))
return false;