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 3f9deec70b92383130b847ef3d9585db5134675e..08c10c518f8323fea7838d92fe03b748cbb2966e 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -65,6 +65,7 @@ config MIPS
        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 9e224469c78887e9c2eb55779bfc8d4646ca2f09..00f2535d22269ae99ec67536878af535f0991b63 100644 (file)
--- 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();