From: Guo Ren <ren_guo@xxxxxxxxx>
The function of do_notify_resume called by entry.S could be entered
in loop when SIGPENDING was setted again before sret. So we must add
prevent code to make syscall restart (regs->sepc -= 0x4) or it may
re-execute unexpected instructions.
Just like in_syscall & forget_syscall used by arm.
Signed-off-by: Guo Ren <ren_guo@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
---
arch/riscv/kernel/signal.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index 837e164..804d6ee 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -234,6 +234,9 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
/* Are we from a system call? */
if (regs->scause == EXC_SYSCALL) {
+ /* Avoid additional syscall restarting via ret_from_exception */
+ regs->scause = -1UL;
+
/* If so, check system call restarting.. */
switch (regs->a0) {
case -ERESTART_RESTARTBLOCK:
@@ -272,6 +275,9 @@ static void do_signal(struct pt_regs *regs)
/* Did we come from a system call? */
if (regs->scause == EXC_SYSCALL) {
+ /* Avoid additional syscall restarting via ret_from_exception */
+ regs->scause = -1UL;
+
/* Restart the system call - no handlers present */
switch (regs->a0) {
case -ERESTARTNOHAND:
--
2.7.4
