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entry: Add support for TIF_NOTIFY_SIGNAL

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Add TIF_NOTIFY_SIGNAL handling in the generic entry code, which if set,
will return true if signal_pending() is used in a wait loop. That causes an
exit of the loop so that notify_signal tracehooks can be run. If the wait
loop is currently inside a system call, the system call is restarted once
task_work has been processed.

In preparation for only having arch_do_signal() handle syscall restarts if
_TIF_SIGPENDING isn't set, rename it to arch_do_signal_or_restart().  Pass
in a boolean that tells the architecture specific signal handler if it
should attempt to get a signal, or just process a potential syscall
restart.

For !CONFIG_GENERIC_ENTRY archs, add the TIF_NOTIFY_SIGNAL handling to
get_signal(). This is done to minimize the needed architecture changes to
support this feature.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20201026203230.386348-3-axboe@kernel.dk
This commit is contained in:
Jens Axboe
2020-10-26 14:32:28 -06:00
committed by Thomas Gleixner
parent 5c251e9dc0
commit 12db8b6900
8 changed files with 77 additions and 11 deletions
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14
kernel/signal.c
View File

@@ -2529,6 +2529,20 @@ bool get_signal(struct ksignal *ksig)
struct signal_struct *signal = current->signal;
int signr;
/*
* 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.
*/
#ifdef TIF_NOTIFY_SIGNAL
if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
if (test_thread_flag(TIF_NOTIFY_SIGNAL))
tracehook_notify_signal();
if (!task_sigpending(current))
return false;
}
#endif
if (unlikely(uprobe_deny_signal()))
return false;