[RFC PATCH for 4.18 03/23] arm: Add restartable sequences support

[Mathieu Desnoyers]

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 
CC: Russell King 
CC: Catalin Marinas 
CC: Will Deacon 
CC: Thomas Gleixner 
CC: Paul Turner 
CC: Andrew Hunter 
CC: Peter Zijlstra 
CC: Andy Lutomirski 
CC: Andi Kleen 
CC: Dave Watson 
CC: Chris Lameter 
CC: Ingo Molnar 
CC: Ben Maurer 
CC: Steven Rostedt 
CC: "Paul E. McKenney" 
CC: Josh Triplett 
CC: Linus Torvalds 
CC: Andrew Morton 
CC: Boqun Feng 
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

[RFC PATCH for 4.18 03/23] arm: Add restartable sequences support

[Mathieu Desnoyers]

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 
CC: Russell King 
CC: Catalin Marinas 
CC: Will Deacon 
CC: Thomas Gleixner 
CC: Paul Turner 
CC: Andrew Hunter 
CC: Peter Zijlstra 
CC: Andy Lutomirski 
CC: Andi Kleen 
CC: Dave Watson 
CC: Chris Lameter 
CC: Ingo Molnar 
CC: Ben Maurer 
CC: Steven Rostedt 
CC: "Paul E. McKenney" 
CC: Josh Triplett 
CC: Linus Torvalds 
CC: Andrew Morton 
CC: Boqun Feng 
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