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![Al Viro](/assets/img/avatar_default.png)
Make sigreturn zero regs->trap, make do_signal() do the same on all paths. As it is, signal interrupting e.g. read() from fd 512 (== ERESTARTSYS) with another signal getting unblocked when the first handler finishes will lead to restart one insn earlier than it ought to. Same for multiple signals with in-kernel handlers interrupting that sucker at the same time. Same for multiple signals of any kind interrupting that sucker on 64bit... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
210 lines
5.3 KiB
C
210 lines
5.3 KiB
C
/*
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* Common signal handling code for both 32 and 64 bits
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*
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* Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
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* Extracted from signal_32.c and signal_64.c
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*
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* This file is subject to the terms and conditions of the GNU General
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* Public License. See the file README.legal in the main directory of
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* this archive for more details.
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*/
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#include <linux/tracehook.h>
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#include <linux/signal.h>
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#include <asm/hw_breakpoint.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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#include "signal.h"
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/* Log an error when sending an unhandled signal to a process. Controlled
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* through debug.exception-trace sysctl.
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*/
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int show_unhandled_signals = 0;
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/*
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* Allocate space for the signal frame
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*/
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void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
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size_t frame_size, int is_32)
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{
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unsigned long oldsp, newsp;
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/* Default to using normal stack */
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oldsp = get_clean_sp(regs, is_32);
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/* Check for alt stack */
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if ((ka->sa.sa_flags & SA_ONSTACK) &&
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current->sas_ss_size && !on_sig_stack(oldsp))
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oldsp = (current->sas_ss_sp + current->sas_ss_size);
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/* Get aligned frame */
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newsp = (oldsp - frame_size) & ~0xFUL;
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/* Check access */
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if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
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return NULL;
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return (void __user *)newsp;
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}
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/*
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* Restore the user process's signal mask
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*/
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void restore_sigmask(sigset_t *set)
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{
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sigdelsetmask(set, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->blocked = *set;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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}
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static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
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int has_handler)
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{
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unsigned long ret = regs->gpr[3];
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int restart = 1;
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/* syscall ? */
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if (TRAP(regs) != 0x0C00)
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return;
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/* error signalled ? */
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if (!(regs->ccr & 0x10000000))
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return;
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switch (ret) {
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case ERESTART_RESTARTBLOCK:
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case ERESTARTNOHAND:
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/* ERESTARTNOHAND means that the syscall should only be
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* restarted if there was no handler for the signal, and since
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* we only get here if there is a handler, we dont restart.
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*/
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restart = !has_handler;
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break;
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case ERESTARTSYS:
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/* ERESTARTSYS means to restart the syscall if there is no
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* handler or the handler was registered with SA_RESTART
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*/
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restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
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break;
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case ERESTARTNOINTR:
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/* ERESTARTNOINTR means that the syscall should be
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* called again after the signal handler returns.
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*/
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break;
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default:
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return;
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}
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if (restart) {
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if (ret == ERESTART_RESTARTBLOCK)
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regs->gpr[0] = __NR_restart_syscall;
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else
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regs->gpr[3] = regs->orig_gpr3;
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regs->nip -= 4;
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regs->result = 0;
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} else {
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regs->result = -EINTR;
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regs->gpr[3] = EINTR;
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regs->ccr |= 0x10000000;
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}
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}
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static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
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{
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siginfo_t info;
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int signr;
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struct k_sigaction ka;
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int ret;
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int is32 = is_32bit_task();
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if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK)
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oldset = ¤t->saved_sigmask;
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else if (!oldset)
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oldset = ¤t->blocked;
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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/* Is there any syscall restart business here ? */
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check_syscall_restart(regs, &ka, signr > 0);
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if (signr <= 0) {
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struct thread_info *ti = current_thread_info();
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/* No signal to deliver -- put the saved sigmask back */
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if (ti->local_flags & _TLF_RESTORE_SIGMASK) {
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ti->local_flags &= ~_TLF_RESTORE_SIGMASK;
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sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
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}
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regs->trap = 0;
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return 0; /* no signals delivered */
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}
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#ifndef CONFIG_PPC_ADV_DEBUG_REGS
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/*
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* Reenable the DABR before delivering the signal to
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* user space. The DABR will have been cleared if it
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* triggered inside the kernel.
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*/
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if (current->thread.dabr)
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set_dabr(current->thread.dabr);
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#endif
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/* Re-enable the breakpoints for the signal stack */
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thread_change_pc(current, regs);
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if (is32) {
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if (ka.sa.sa_flags & SA_SIGINFO)
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ret = handle_rt_signal32(signr, &ka, &info, oldset,
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regs);
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else
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ret = handle_signal32(signr, &ka, &info, oldset,
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regs);
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} else {
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ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
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}
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regs->trap = 0;
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if (ret) {
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spin_lock_irq(¤t->sighand->siglock);
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sigorsets(¤t->blocked, ¤t->blocked,
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&ka.sa.sa_mask);
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if (!(ka.sa.sa_flags & SA_NODEFER))
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sigaddset(¤t->blocked, signr);
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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/*
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* A signal was successfully delivered; the saved sigmask is in
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* its frame, and we can clear the TLF_RESTORE_SIGMASK flag.
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*/
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current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;
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/*
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* Let tracing know that we've done the handler setup.
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*/
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tracehook_signal_handler(signr, &info, &ka, regs,
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test_thread_flag(TIF_SINGLESTEP));
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}
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return ret;
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}
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void do_signal(struct pt_regs *regs, unsigned long thread_info_flags)
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{
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if (thread_info_flags & _TIF_SIGPENDING)
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do_signal_pending(NULL, regs);
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if (thread_info_flags & _TIF_NOTIFY_RESUME) {
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clear_thread_flag(TIF_NOTIFY_RESUME);
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tracehook_notify_resume(regs);
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}
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}
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long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
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unsigned long r5, unsigned long r6, unsigned long r7,
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unsigned long r8, struct pt_regs *regs)
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{
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return do_sigaltstack(uss, uoss, regs->gpr[1]);
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}
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