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riscv/signal: Fixup additional syscall restarting 

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@c-sky.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Guo Ren 2019-04-02 16:02:33 +08:00 committed by Palmer Dabbelt
parent 085b775580
commit 7a64f3f1cf
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1 changed files with 6 additions and 0 deletions
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6
arch/riscv/kernel/signal.c
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@ -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: