Commit 8f5a00eb authored by Al Viro's avatar Al Viro Committed by Ralf Baechle

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: default avatarAl 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent e5b377a8
...@@ -40,7 +40,6 @@ int __compute_return_epc(struct pt_regs *regs) ...@@ -40,7 +40,6 @@ int __compute_return_epc(struct pt_regs *regs)
return -EFAULT; return -EFAULT;
} }
regs->regs[0] = 0;
switch (insn.i_format.opcode) { switch (insn.i_format.opcode) {
/* /*
* jr and jalr are in r_format format. * jr and jalr are in r_format format.
......
...@@ -63,9 +63,9 @@ stack_done: ...@@ -63,9 +63,9 @@ stack_done:
sw t0, PT_R7(sp) # set error flag sw t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
lw t1, PT_R2(sp) # syscall number
negu v0 # error negu v0 # error
sw v0, PT_R0(sp) # set flag for syscall sw t1, PT_R0(sp) # save it for syscall restarting
# restarting
1: sw v0, PT_R2(sp) # result 1: sw v0, PT_R2(sp) # result
o32_syscall_exit: o32_syscall_exit:
...@@ -104,9 +104,9 @@ syscall_trace_entry: ...@@ -104,9 +104,9 @@ syscall_trace_entry:
sw t0, PT_R7(sp) # set error flag sw t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
lw t1, PT_R2(sp) # syscall number
negu v0 # error negu v0 # error
sw v0, PT_R0(sp) # set flag for syscall sw t1, PT_R0(sp) # save it for syscall restarting
# restarting
1: sw v0, PT_R2(sp) # result 1: sw v0, PT_R2(sp) # result
j syscall_exit j syscall_exit
...@@ -170,7 +170,6 @@ stackargs: ...@@ -170,7 +170,6 @@ stackargs:
*/ */
bad_stack: bad_stack:
negu v0 # error negu v0 # error
sw v0, PT_R0(sp)
sw v0, PT_R2(sp) sw v0, PT_R2(sp)
li t0, 1 # set error flag li t0, 1 # set error flag
sw t0, PT_R7(sp) sw t0, PT_R7(sp)
......
...@@ -66,9 +66,9 @@ NESTED(handle_sys64, PT_SIZE, sp) ...@@ -66,9 +66,9 @@ NESTED(handle_sys64, PT_SIZE, sp)
sd t0, PT_R7(sp) # set error flag sd t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp) # set flag for syscall sd t1, PT_R0(sp) # save it for syscall restarting
# restarting
1: sd v0, PT_R2(sp) # result 1: sd v0, PT_R2(sp) # result
n64_syscall_exit: n64_syscall_exit:
...@@ -109,8 +109,9 @@ syscall_trace_entry: ...@@ -109,8 +109,9 @@ syscall_trace_entry:
sd t0, PT_R7(sp) # set error flag sd t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp) # set flag for syscall restarting sd t1, PT_R0(sp) # save it for syscall restarting
1: sd v0, PT_R2(sp) # result 1: sd v0, PT_R2(sp) # result
j syscall_exit j syscall_exit
......
...@@ -65,8 +65,9 @@ NESTED(handle_sysn32, PT_SIZE, sp) ...@@ -65,8 +65,9 @@ NESTED(handle_sysn32, PT_SIZE, sp)
sd t0, PT_R7(sp) # set error flag sd t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp) # set flag for syscall restarting sd t1, PT_R0(sp) # save it for syscall restarting
1: sd v0, PT_R2(sp) # result 1: sd v0, PT_R2(sp) # result
local_irq_disable # make sure need_resched and local_irq_disable # make sure need_resched and
...@@ -106,8 +107,9 @@ n32_syscall_trace_entry: ...@@ -106,8 +107,9 @@ n32_syscall_trace_entry:
sd t0, PT_R7(sp) # set error flag sd t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp) # set flag for syscall restarting sd t1, PT_R0(sp) # save it for syscall restarting
1: sd v0, PT_R2(sp) # result 1: sd v0, PT_R2(sp) # result
j syscall_exit j syscall_exit
......
...@@ -93,8 +93,9 @@ NESTED(handle_sys, PT_SIZE, sp) ...@@ -93,8 +93,9 @@ NESTED(handle_sys, PT_SIZE, sp)
sd t0, PT_R7(sp) # set error flag sd t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp) # flag for syscall restarting sd t1, PT_R0(sp) # save it for syscall restarting
1: sd v0, PT_R2(sp) # result 1: sd v0, PT_R2(sp) # result
o32_syscall_exit: o32_syscall_exit:
...@@ -142,8 +143,9 @@ trace_a_syscall: ...@@ -142,8 +143,9 @@ trace_a_syscall:
sd t0, PT_R7(sp) # set error flag sd t0, PT_R7(sp) # set error flag
beqz t0, 1f beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp) # set flag for syscall restarting sd t1, PT_R0(sp) # save it for syscall restarting
1: sd v0, PT_R2(sp) # result 1: sd v0, PT_R2(sp) # result
j syscall_exit j syscall_exit
...@@ -155,7 +157,6 @@ trace_a_syscall: ...@@ -155,7 +157,6 @@ trace_a_syscall:
*/ */
bad_stack: bad_stack:
dnegu v0 # error dnegu v0 # error
sd v0, PT_R0(sp)
sd v0, PT_R2(sp) sd v0, PT_R2(sp)
li t0, 1 # set error flag li t0, 1 # set error flag
sd t0, PT_R7(sp) sd t0, PT_R7(sp)
......
...@@ -550,23 +550,26 @@ static int handle_signal(unsigned long sig, siginfo_t *info, ...@@ -550,23 +550,26 @@ static int handle_signal(unsigned long sig, siginfo_t *info,
struct mips_abi *abi = current->thread.abi; struct mips_abi *abi = current->thread.abi;
void *vdso = current->mm->context.vdso; void *vdso = current->mm->context.vdso;
switch(regs->regs[0]) { if (regs->regs[0]) {
case ERESTART_RESTARTBLOCK: switch(regs->regs[2]) {
case ERESTARTNOHAND: case ERESTART_RESTARTBLOCK:
regs->regs[2] = EINTR; case ERESTARTNOHAND:
break;
case ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->regs[2] = EINTR; regs->regs[2] = EINTR;
break; 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)) if (sig_uses_siginfo(ka))
ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset, ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
...@@ -625,17 +628,13 @@ static void do_signal(struct pt_regs *regs) ...@@ -625,17 +628,13 @@ static void do_signal(struct pt_regs *regs)
return; 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[0]) {
if (regs->regs[2] == ERESTARTNOHAND || if (regs->regs[2] == ERESTARTNOHAND ||
regs->regs[2] == ERESTARTSYS || regs->regs[2] == ERESTARTSYS ||
regs->regs[2] == ERESTARTNOINTR) { regs->regs[2] == ERESTARTNOINTR) {
regs->regs[2] = regs->regs[0];
regs->regs[7] = regs->regs[26]; regs->regs[7] = regs->regs[26];
regs->cp0_epc -= 8; regs->cp0_epc -= 4;
} }
if (regs->regs[2] == ERESTART_RESTARTBLOCK) { if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
regs->regs[2] = current->thread.abi->restart; regs->regs[2] = current->thread.abi->restart;
......
...@@ -109,8 +109,6 @@ static void emulate_load_store_insn(struct pt_regs *regs, ...@@ -109,8 +109,6 @@ static void emulate_load_store_insn(struct pt_regs *regs,
unsigned long value; unsigned long value;
unsigned int res; unsigned int res;
regs->regs[0] = 0;
/* /*
* This load never faults. * This load never faults.
*/ */
......
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