diff options
| author | Sven Schnelle <svens@linux.ibm.com> | 2021-06-25 15:02:08 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2021-07-08 22:09:47 +0200 |
| commit | df29a7440c4b5c65765c8f60396b3b13063e24e9 (patch) | |
| tree | eb0c060e0678fb18fa4eeadd2d9b2000757f6913 /arch/s390/kernel/syscall.c | |
| parent | 779df2248739b6308c03b354c99e4c352141e3bc (diff) | |
s390/signal: switch to using vdso for sigreturn and syscall restart
with generic entry, there's a bug when it comes to restarting of signals.
The failing sequence is:
a) a signal is coming in, and no handler is registered, so the lower
part of arch_do_signal_or_restart() in arch/s390/kernel/signal.c
sets PIF_SYSCALL_RESTART.
b) a second signal gets pending while the kernel is still in the exit
loop, and for that one, a handler exists.
c) The first part of arch_do_signal_or_restart() is called. That part
calls handle_signal(), which sets up stack + registers for handling
the signal.
d) __do_syscall() in arch/s390/kernel/syscall.c checks for
PIF_SYSCALL_RESTART right before leaving to userspace. If it is set,
it restart's the syscall. However, the registers are already setup
for handling a signal from c). The syscall is now restarted with the
wrong arguments.
Change the code to:
- use vdso for syscall_restart() instead of PIF_SYSCALL_RESTART because
we cannot rewind and go back to userspace on s390 because the system call
number might be encoded in the svc instruction.
- for all other syscalls we rewind the PSW and return to userspace.
Cc: <stable@kernel.org> # v5.12+ d57778feb987: s390/vdso: always enable vdso
Cc: <stable@kernel.org> # v5.12+ 686341f2548b: s390/vdso64: add sigreturn,rt_sigreturn and restart_syscall
Cc: <stable@kernel.org> # v5.12+ 43e1f76b0b69: s390/vdso: rename VDSO64_LBASE to VDSO_LBASE
Cc: <stable@kernel.org> # v5.12+ 779df2248739: s390/vdso: add minimal compat vdso
Cc: <stable@kernel.org> # v5.12+
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/syscall.c')
| -rw-r--r-- | arch/s390/kernel/syscall.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/kernel/syscall.c b/arch/s390/kernel/syscall.c index 76f7916cc30f..c6b99da0738b 100644 --- a/arch/s390/kernel/syscall.c +++ b/arch/s390/kernel/syscall.c @@ -121,6 +121,10 @@ void do_syscall(struct pt_regs *regs) regs->gprs[2] = nr; + if (nr == __NR_restart_syscall && !(current->restart_block.arch_data & 1)) { + regs->psw.addr = current->restart_block.arch_data; + current->restart_block.arch_data = 1; + } nr = syscall_enter_from_user_mode_work(regs, nr); /* |