openrisc: Add support for restartable sequences

Implement support for restartable sequences on OpenRISC by doing:
 - Select HAVE_RSEQ in Kconfig
 - Call rseq_syscall() on return to userspace when CONFIG_DEBUG_RSEQ
   is enabled.
 - Call rseq_signal_deliver() to fixup the pre-signal stack frame when a
   signal is delivered on top of a restartable sequence critical section

Cc: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 607a59bc2a22d823e8f0bfa1e21a505c91005604..b38fee299bc48a134d8af8d558ea2c88fb197e81 100644 (file)
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -28,6 +28,7 @@ config OPENRISC
        select HAVE_UID16
        select HAVE_PAGE_SIZE_8KB
        select HAVE_REGS_AND_STACK_ACCESS_API
+       select HAVE_RSEQ
        select GENERIC_ATOMIC64
        select GENERIC_CLOCKEVENTS_BROADCAST
        select GENERIC_SMP_IDLE_THREAD

diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S
index ce6f2b08a35edc6cccd03937344db736031ee9ec..c7e90b09645e4dc9dec9af8f9c2b1ab502c1509d 100644 (file)
--- a/arch/openrisc/kernel/entry.S
+++ b/arch/openrisc/kernel/entry.S
@@ -714,6 +714,10 @@ _syscall_check_trace_leave:
  * interrupts that set NEED_RESCHED or SIGNALPENDING... really true? */
 
 _syscall_check_work:
+#ifdef CONFIG_DEBUG_RSEQ
+       l.jal   rseq_syscall
+        l.ori  r3,r1,0
+#endif
        /* Here we need to disable interrupts */
        DISABLE_INTERRUPTS(r27,r29)
        TRACE_IRQS_OFF

diff --git a/arch/openrisc/kernel/signal.c b/arch/openrisc/kernel/signal.c
index c7ab42e2cb7a4f3dc21742d7171fb02be12057f6..f70a13ee059365679e505a0dc5f871bad6f7007c 100644 (file)
--- a/arch/openrisc/kernel/signal.c
+++ b/arch/openrisc/kernel/signal.c
@@ -244,6 +244,8 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 {
        int ret;
 
+       rseq_signal_deliver(ksig, regs);
+
        ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 
        signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));