diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 21a4d0e111bc..88b6220b2608 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -384,30 +384,6 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) sigset_t *oldset = sigmask_to_save(); int ret; - /* Are we from a system call? */ - if (regs->cause == EXC_SYSCALL) { - /* Avoid additional syscall restarting via ret_from_exception */ - regs->cause = -1UL; - /* If so, check system call restarting.. */ - switch (regs->a0) { - case -ERESTART_RESTARTBLOCK: - case -ERESTARTNOHAND: - regs->a0 = -EINTR; - break; - - case -ERESTARTSYS: - if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { - regs->a0 = -EINTR; - break; - } - fallthrough; - case -ERESTARTNOINTR: - regs->a0 = regs->orig_a0; - regs->epc -= 0x4; - break; - } - } - rseq_signal_deliver(ksig, regs); /* Set up the stack frame */ @@ -421,34 +397,65 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) void arch_do_signal_or_restart(struct pt_regs *regs) { + unsigned long continue_addr = 0, restart_addr = 0; + int retval = 0; struct ksignal ksig; + bool syscall = (regs->cause == EXC_SYSCALL); + /* If we were from a system call, check for system call restarting */ + if (syscall) { + continue_addr = regs->epc; + restart_addr = continue_addr - 4; + retval = regs->a0; + + /* Avoid additional syscall restarting via ret_from_exception */ + regs->cause = -1UL; + + /* + * Prepare for system call restart. We do this here so that a + * debugger will see the already changed PC. + */ + switch (retval) { + case -ERESTARTNOHAND: + case -ERESTARTSYS: + case -ERESTARTNOINTR: + case -ERESTART_RESTARTBLOCK: + regs->a0 = regs->orig_a0; + regs->epc = restart_addr; + break; + } + } + + /* + * Get the signal to deliver. When running under ptrace, at this point + * the debugger may change all of our registers. + */ if (get_signal(&ksig)) { + /* + * Depending on the signal settings, we may need to revert the + * decision to restart the system call, but skip this if a + * debugger has chosen to restart at a different PC. + */ + if (regs->epc == restart_addr && + (retval == -ERESTARTNOHAND || + retval == -ERESTART_RESTARTBLOCK || + (retval == -ERESTARTSYS && + !(ksig.ka.sa.sa_flags & SA_RESTART)))) { + regs->a0 = -EINTR; + regs->epc = continue_addr; + } + /* Actually deliver the signal */ handle_signal(&ksig, regs); return; } - /* Did we come from a system call? */ - if (regs->cause == EXC_SYSCALL) { - /* Avoid additional syscall restarting via ret_from_exception */ - regs->cause = -1UL; - - /* Restart the system call - no handlers present */ - switch (regs->a0) { - case -ERESTARTNOHAND: - case -ERESTARTSYS: - case -ERESTARTNOINTR: - regs->a0 = regs->orig_a0; - regs->epc -= 0x4; - break; - case -ERESTART_RESTARTBLOCK: - regs->a0 = regs->orig_a0; - regs->a7 = __NR_restart_syscall; - regs->epc -= 0x4; - break; - } - } + /* + * Handle restarting a different system call. As above, if a debugger + * has chosen to restart at a different PC, ignore the restart. + */ + if (syscall && regs->epc == restart_addr && retval == -ERESTART_RESTARTBLOCK) + regs->a7 = __NR_restart_syscall; /* * If there is no signal to deliver, we just put the saved