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

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>
CC: Russell King <li...@arm.linux.org.uk>
CC: Catalin Marinas <catalin.mari...@arm.com>
CC: Will Deacon <will.dea...@arm.com>
CC: Thomas Gleixner <t...@linutronix.de>
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: 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/arm/Kconfig         | 1 +
 arch/arm/kernel/signal.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7e3d53575486..1897d40ddd87 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -90,6 +90,7 @@ config ARM
        select HAVE_PERF_USER_STACK_DUMP
        select HAVE_RCU_TABLE_FREE if (SMP && ARM_LPAE)
        select HAVE_REGS_AND_STACK_ACCESS_API
+       select HAVE_RSEQ
        select HAVE_SYSCALL_TRACEPOINTS
        select HAVE_UID16
        select HAVE_VIRT_CPU_ACCOUNTING_GEN
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index bd8810d4acb3..5879ab3f53c1 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -541,6 +541,12 @@ static void handle_signal(struct ksignal *ksig, struct 
pt_regs *regs)
        int ret;
 
        /*
+        * Increment event counter and perform fixup for the pre-signal
+        * frame.
+        */
+       rseq_signal_deliver(regs);
+
+       /*
         * Set up the stack frame
         */
        if (ksig->ka.sa.sa_flags & SA_SIGINFO)
@@ -660,6 +666,7 @@ do_work_pending(struct pt_regs *regs, unsigned int 
thread_flags, int syscall)
                        } else {
                                clear_thread_flag(TIF_NOTIFY_RESUME);
                                tracehook_notify_resume(regs);
+                               rseq_handle_notify_resume(regs);
                        }
                }
                local_irq_disable();
-- 
2.11.0

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