MIPS: Add support for restartable sequences
Implement support for restartable sequences on MIPS, which requires 3
simple things:
- Call rseq_handle_notify_resume() on return to userspace if
TIF_NOTIFY_RESUME is set.
- Call rseq_signal_deliver() to fixup the pre-signal stack frame when
a signal is delivered whilst executing a restartable sequence
critical section.
- Select CONFIG_HAVE_RSEQ.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: James Hogan <jhogan@kernel.org>
Patchwork: https://patchwork.linux-mips.org/patch/19523/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 3f9deec..08c10c5 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -65,6 +65,7 @@
select HAVE_OPROFILE
select HAVE_PERF_EVENTS
select HAVE_REGS_AND_STACK_ACCESS_API
+ select HAVE_RSEQ
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_VIRT_CPU_ACCOUNTING_GEN if 64BIT || !SMP
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 9e22446..00f2535 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -801,6 +801,8 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
regs->regs[0] = 0; /* Don't deal with this again. */
}
+ rseq_signal_deliver(regs);
+
if (sig_uses_siginfo(&ksig->ka, abi))
ret = abi->setup_rt_frame(vdso + abi->vdso->off_rt_sigreturn,
ksig, regs, oldset);
@@ -868,6 +870,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
+ rseq_handle_notify_resume(regs);
}
user_enter();
