MIPS: Sanitize restart logics
Put the original syscall number into ->regs[0] when we leave syscall
with error. Use it in restart logics. Everything else will have
it 0 since we pass through SAVE_SOME on all the ways in. Note that
in places like bad_stack and inllegal_syscall we leave it 0 - it's not
restartable.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1698/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index b3273ae..604f077 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -550,23 +550,26 @@
struct mips_abi *abi = current->thread.abi;
void *vdso = current->mm->context.vdso;
- switch(regs->regs[0]) {
- case ERESTART_RESTARTBLOCK:
- case ERESTARTNOHAND:
- regs->regs[2] = EINTR;
- break;
- case ERESTARTSYS:
- if (!(ka->sa.sa_flags & SA_RESTART)) {
+ if (regs->regs[0]) {
+ switch(regs->regs[2]) {
+ case ERESTART_RESTARTBLOCK:
+ case ERESTARTNOHAND:
regs->regs[2] = EINTR;
break;
+ case ERESTARTSYS:
+ if (!(ka->sa.sa_flags & SA_RESTART)) {
+ regs->regs[2] = EINTR;
+ break;
+ }
+ /* fallthrough */
+ case ERESTARTNOINTR:
+ regs->regs[7] = regs->regs[26];
+ regs->regs[2] = regs->regs[0];
+ regs->cp0_epc -= 4;
}
- /* fallthrough */
- case ERESTARTNOINTR: /* Userland will reload $v0. */
- regs->regs[7] = regs->regs[26];
- regs->cp0_epc -= 8;
- }
- regs->regs[0] = 0; /* Don't deal with this again. */
+ regs->regs[0] = 0; /* Don't deal with this again. */
+ }
if (sig_uses_siginfo(ka))
ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
@@ -625,17 +628,13 @@
return;
}
- /*
- * Who's code doesn't conform to the restartable syscall convention
- * dies here!!! The li instruction, a single machine instruction,
- * must directly be followed by the syscall instruction.
- */
if (regs->regs[0]) {
if (regs->regs[2] == ERESTARTNOHAND ||
regs->regs[2] == ERESTARTSYS ||
regs->regs[2] == ERESTARTNOINTR) {
+ regs->regs[2] = regs->regs[0];
regs->regs[7] = regs->regs[26];
- regs->cp0_epc -= 8;
+ regs->cp0_epc -= 4;
}
if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
regs->regs[2] = current->thread.abi->restart;