Call the rseq_handle_notify_resume() function on return to userspace if
TIF_NOTIFY_RESUME thread flag is set.

Increment the event counter and perform fixup on the pre-signal frame
when a signal is delivered on top of a restartable sequence critical
section.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Reviewed-by: Thomas Gleixner <t...@linutronix.de>
CC: Russell King <li...@arm.linux.org.uk>
CC: Catalin Marinas <catalin.mari...@arm.com>
CC: Will Deacon <will.dea...@arm.com>
CC: Paul Turner <p...@google.com>
CC: Andrew Hunter <a...@google.com>
CC: Peter Zijlstra <pet...@infradead.org>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Andi Kleen <a...@firstfloor.org>
CC: Dave Watson <davejwat...@fb.com>
CC: Chris Lameter <c...@linux.com>
CC: Ingo Molnar <mi...@redhat.com>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: Ben Maurer <bmau...@fb.com>
CC: Steven Rostedt <rost...@goodmis.org>
CC: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
CC: Josh Triplett <j...@joshtriplett.org>
CC: Linus Torvalds <torva...@linux-foundation.org>
CC: Andrew Morton <a...@linux-foundation.org>
CC: Boqun Feng <boqun.f...@gmail.com>
CC: linux-...@vger.kernel.org
---
 arch/x86/Kconfig         | 1 +
 arch/x86/entry/common.c  | 1 +
 arch/x86/kernel/signal.c | 6 ++++++
 3 files changed, 8 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8eed3f94bfc7..aa86dab90a95 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -174,6 +174,7 @@ config X86
        select HAVE_REGS_AND_STACK_ACCESS_API
        select HAVE_RELIABLE_STACKTRACE         if X86_64 && 
UNWINDER_FRAME_POINTER && STACK_VALIDATION
        select HAVE_STACK_VALIDATION            if X86_64
+       select HAVE_RSEQ
        select HAVE_SYSCALL_TRACEPOINTS
        select HAVE_UNSTABLE_SCHED_CLOCK
        select HAVE_USER_RETURN_NOTIFIER
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index d7d3cc24baf4..d65595b201f4 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -160,6 +160,7 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 
cached_flags)
                if (cached_flags & _TIF_NOTIFY_RESUME) {
                        clear_thread_flag(TIF_NOTIFY_RESUME);
                        tracehook_notify_resume(regs);
+                       rseq_handle_notify_resume(regs);
                }
 
                if (cached_flags & _TIF_USER_RETURN_NOTIFY)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b9e00e8f1c9b..991017d26d00 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -687,6 +687,12 @@ setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
        sigset_t *set = sigmask_to_save();
        compat_sigset_t *cset = (compat_sigset_t *) set;
 
+       /*
+        * Increment event counter and perform fixup for the pre-signal
+        * frame.
+        */
+       rseq_signal_deliver(regs);
+
        /* Set up the stack frame */
        if (is_ia32_frame(ksig)) {
                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
-- 
2.11.0

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