13fdd31abe
In entry.S resume_userspace ... jal do_notify_resume form a loop through which the kernel will iterate as long as work is pending. If we iterate through this loop more than once with no signal pending for at least one but the last iteration we will take do the syscall restarting multiple times resulting in a syscall return prior to the the syscall instruction in userspace. This may happen when debugging a multithreaded program. Debugging and original fix by Maciej; extended to other ABIs by me. Signed-off-by: Maciej W. Rozycki <macro@mips.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
490 lines
13 KiB
C
490 lines
13 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 1994 - 2000 Ralf Baechle
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* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
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*/
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#include <linux/cache.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/personality.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/wait.h>
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#include <linux/ptrace.h>
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#include <linux/unistd.h>
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#include <linux/compiler.h>
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#include <asm/abi.h>
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#include <asm/asm.h>
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#include <linux/bitops.h>
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#include <asm/cacheflush.h>
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#include <asm/fpu.h>
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#include <asm/sim.h>
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#include <asm/uaccess.h>
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#include <asm/ucontext.h>
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#include <asm/cpu-features.h>
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#include <asm/war.h>
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#include "signal-common.h"
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#define DEBUG_SIG 0
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#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
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/*
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* Atomically swap in the new signal mask, and wait for a signal.
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*/
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#ifdef CONFIG_TRAD_SIGNALS
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save_static_function(sys_sigsuspend);
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__attribute_used__ noinline static int
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_sys_sigsuspend(nabi_no_regargs struct pt_regs regs)
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{
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sigset_t newset;
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sigset_t __user *uset;
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uset = (sigset_t __user *) regs.regs[4];
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if (copy_from_user(&newset, uset, sizeof(sigset_t)))
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return -EFAULT;
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sigdelsetmask(&newset, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->saved_sigmask = current->blocked;
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current->blocked = newset;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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set_thread_flag(TIF_RESTORE_SIGMASK);
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return -ERESTARTNOHAND;
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}
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#endif
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save_static_function(sys_rt_sigsuspend);
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__attribute_used__ noinline static int
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_sys_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
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{
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sigset_t newset;
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sigset_t __user *unewset;
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size_t sigsetsize;
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/* XXX Don't preclude handling different sized sigset_t's. */
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sigsetsize = regs.regs[5];
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if (sigsetsize != sizeof(sigset_t))
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return -EINVAL;
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unewset = (sigset_t __user *) regs.regs[4];
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if (copy_from_user(&newset, unewset, sizeof(newset)))
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return -EFAULT;
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sigdelsetmask(&newset, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->saved_sigmask = current->blocked;
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current->blocked = newset;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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set_thread_flag(TIF_RESTORE_SIGMASK);
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return -ERESTARTNOHAND;
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}
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#ifdef CONFIG_TRAD_SIGNALS
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asmlinkage int sys_sigaction(int sig, const struct sigaction __user *act,
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struct sigaction __user *oact)
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{
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struct k_sigaction new_ka, old_ka;
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int ret;
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int err = 0;
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if (act) {
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old_sigset_t mask;
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if (!access_ok(VERIFY_READ, act, sizeof(*act)))
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return -EFAULT;
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err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
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err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
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err |= __get_user(mask, &act->sa_mask.sig[0]);
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if (err)
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return -EFAULT;
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siginitset(&new_ka.sa.sa_mask, mask);
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}
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ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
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if (!ret && oact) {
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if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
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return -EFAULT;
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err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
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err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
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err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
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err |= __put_user(0, &oact->sa_mask.sig[1]);
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err |= __put_user(0, &oact->sa_mask.sig[2]);
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err |= __put_user(0, &oact->sa_mask.sig[3]);
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if (err)
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return -EFAULT;
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}
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return ret;
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}
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#endif
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asmlinkage int sys_sigaltstack(nabi_no_regargs struct pt_regs regs)
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{
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const stack_t __user *uss = (const stack_t __user *) regs.regs[4];
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stack_t __user *uoss = (stack_t __user *) regs.regs[5];
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unsigned long usp = regs.regs[29];
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return do_sigaltstack(uss, uoss, usp);
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}
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/*
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* Horribly complicated - with the bloody RM9000 workarounds enabled
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* the signal trampolines is moving to the end of the structure so we can
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* increase the alignment without breaking software compatibility.
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*/
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#ifdef CONFIG_TRAD_SIGNALS
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struct sigframe {
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u32 sf_ass[4]; /* argument save space for o32 */
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#if ICACHE_REFILLS_WORKAROUND_WAR
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u32 sf_pad[2];
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#else
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u32 sf_code[2]; /* signal trampoline */
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#endif
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struct sigcontext sf_sc;
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sigset_t sf_mask;
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#if ICACHE_REFILLS_WORKAROUND_WAR
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u32 sf_code[8] ____cacheline_aligned; /* signal trampoline */
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#endif
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};
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#endif
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struct rt_sigframe {
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u32 rs_ass[4]; /* argument save space for o32 */
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#if ICACHE_REFILLS_WORKAROUND_WAR
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u32 rs_pad[2];
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#else
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u32 rs_code[2]; /* signal trampoline */
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#endif
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struct siginfo rs_info;
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struct ucontext rs_uc;
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#if ICACHE_REFILLS_WORKAROUND_WAR
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u32 rs_code[8] ____cacheline_aligned; /* signal trampoline */
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#endif
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};
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#ifdef CONFIG_TRAD_SIGNALS
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save_static_function(sys_sigreturn);
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__attribute_used__ noinline static void
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_sys_sigreturn(nabi_no_regargs struct pt_regs regs)
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{
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struct sigframe __user *frame;
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sigset_t blocked;
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frame = (struct sigframe __user *) regs.regs[29];
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
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goto badframe;
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sigdelsetmask(&blocked, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->blocked = blocked;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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if (restore_sigcontext(®s, &frame->sf_sc))
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goto badframe;
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/*
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* Don't let your children do this ...
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*/
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__asm__ __volatile__(
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"move\t$29, %0\n\t"
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"j\tsyscall_exit"
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:/* no outputs */
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:"r" (®s));
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/* Unreached */
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badframe:
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force_sig(SIGSEGV, current);
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}
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#endif /* CONFIG_TRAD_SIGNALS */
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save_static_function(sys_rt_sigreturn);
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__attribute_used__ noinline static void
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_sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
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{
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struct rt_sigframe __user *frame;
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sigset_t set;
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stack_t st;
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frame = (struct rt_sigframe __user *) regs.regs[29];
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
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goto badframe;
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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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if (restore_sigcontext(®s, &frame->rs_uc.uc_mcontext))
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goto badframe;
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if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
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goto badframe;
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/* It is more difficult to avoid calling this function than to
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call it and ignore errors. */
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do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);
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/*
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* Don't let your children do this ...
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*/
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__asm__ __volatile__(
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"move\t$29, %0\n\t"
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"j\tsyscall_exit"
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:/* no outputs */
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:"r" (®s));
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/* Unreached */
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badframe:
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force_sig(SIGSEGV, current);
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}
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#ifdef CONFIG_TRAD_SIGNALS
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int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set)
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{
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struct sigframe __user *frame;
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int err = 0;
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frame = get_sigframe(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
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goto give_sigsegv;
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install_sigtramp(frame->sf_code, __NR_sigreturn);
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err |= setup_sigcontext(regs, &frame->sf_sc);
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err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
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if (err)
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goto give_sigsegv;
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/*
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* Arguments to signal handler:
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*
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* a0 = signal number
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* a1 = 0 (should be cause)
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* a2 = pointer to struct sigcontext
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*
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* $25 and c0_epc point to the signal handler, $29 points to the
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* struct sigframe.
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*/
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regs->regs[ 4] = signr;
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regs->regs[ 5] = 0;
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regs->regs[ 6] = (unsigned long) &frame->sf_sc;
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regs->regs[29] = (unsigned long) frame;
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regs->regs[31] = (unsigned long) frame->sf_code;
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regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
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#if DEBUG_SIG
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printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
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current->comm, current->pid,
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frame, regs->cp0_epc, frame->regs[31]);
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#endif
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return 0;
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give_sigsegv:
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force_sigsegv(signr, current);
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return -EFAULT;
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}
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#endif
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int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
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int signr, sigset_t *set, siginfo_t *info)
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{
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struct rt_sigframe __user *frame;
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int err = 0;
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frame = get_sigframe(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
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goto give_sigsegv;
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install_sigtramp(frame->rs_code, __NR_rt_sigreturn);
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/* Create siginfo. */
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err |= copy_siginfo_to_user(&frame->rs_info, info);
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/* Create the ucontext. */
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err |= __put_user(0, &frame->rs_uc.uc_flags);
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err |= __put_user(NULL, &frame->rs_uc.uc_link);
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err |= __put_user((void __user *)current->sas_ss_sp,
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&frame->rs_uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->regs[29]),
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&frame->rs_uc.uc_stack.ss_flags);
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err |= __put_user(current->sas_ss_size,
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&frame->rs_uc.uc_stack.ss_size);
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err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
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err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
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if (err)
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goto give_sigsegv;
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/*
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* Arguments to signal handler:
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*
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* a0 = signal number
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* a1 = 0 (should be cause)
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* a2 = pointer to ucontext
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*
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* $25 and c0_epc point to the signal handler, $29 points to
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* the struct rt_sigframe.
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*/
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regs->regs[ 4] = signr;
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regs->regs[ 5] = (unsigned long) &frame->rs_info;
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regs->regs[ 6] = (unsigned long) &frame->rs_uc;
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regs->regs[29] = (unsigned long) frame;
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regs->regs[31] = (unsigned long) frame->rs_code;
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regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
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#if DEBUG_SIG
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printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
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current->comm, current->pid,
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frame, regs->cp0_epc, regs->regs[31]);
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#endif
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return 0;
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give_sigsegv:
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force_sigsegv(signr, current);
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return -EFAULT;
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}
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static inline int handle_signal(unsigned long sig, siginfo_t *info,
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struct k_sigaction *ka, sigset_t *oldset, struct pt_regs *regs)
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{
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int ret;
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switch(regs->regs[0]) {
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case ERESTART_RESTARTBLOCK:
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case ERESTARTNOHAND:
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regs->regs[2] = EINTR;
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break;
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case ERESTARTSYS:
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if (!(ka->sa.sa_flags & SA_RESTART)) {
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regs->regs[2] = EINTR;
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break;
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}
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/* fallthrough */
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case ERESTARTNOINTR: /* Userland will reload $v0. */
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regs->regs[7] = regs->regs[26];
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regs->cp0_epc -= 8;
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}
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regs->regs[0] = 0; /* Don't deal with this again. */
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if (sig_uses_siginfo(ka))
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ret = current->thread.abi->setup_rt_frame(ka, regs, sig, oldset, info);
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else
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ret = current->thread.abi->setup_frame(ka, regs, sig, oldset);
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spin_lock_irq(¤t->sighand->siglock);
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sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask);
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if (!(ka->sa.sa_flags & SA_NODEFER))
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sigaddset(¤t->blocked,sig);
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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return ret;
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}
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void do_signal(struct pt_regs *regs)
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{
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struct k_sigaction ka;
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sigset_t *oldset;
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siginfo_t info;
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int signr;
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/*
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* We want the common case to go fast, which is why we may in certain
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* cases get here from kernel mode. Just return without doing anything
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* if so.
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*/
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if (!user_mode(regs))
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return;
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if (test_thread_flag(TIF_RESTORE_SIGMASK))
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oldset = ¤t->saved_sigmask;
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else
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oldset = ¤t->blocked;
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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if (signr > 0) {
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/* Whee! Actually deliver the signal. */
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if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
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/*
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* A signal was successfully delivered; the saved
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* sigmask will have been stored in the signal frame,
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* and will be restored by sigreturn, so we can simply
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* clear the TIF_RESTORE_SIGMASK flag.
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*/
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if (test_thread_flag(TIF_RESTORE_SIGMASK))
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clear_thread_flag(TIF_RESTORE_SIGMASK);
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}
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return;
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}
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/*
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* Who's code doesn't conform to the restartable syscall convention
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* dies here!!! The li instruction, a single machine instruction,
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* must directly be followed by the syscall instruction.
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*/
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if (regs->regs[0]) {
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if (regs->regs[2] == ERESTARTNOHAND ||
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regs->regs[2] == ERESTARTSYS ||
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regs->regs[2] == ERESTARTNOINTR) {
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regs->regs[7] = regs->regs[26];
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regs->cp0_epc -= 8;
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}
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if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
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regs->regs[2] = __NR_restart_syscall;
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regs->regs[7] = regs->regs[26];
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regs->cp0_epc -= 4;
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}
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regs->regs[0] = 0; /* Don't deal with this again. */
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}
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/*
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* If there's no signal to deliver, we just put the saved sigmask
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* back
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*/
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if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
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clear_thread_flag(TIF_RESTORE_SIGMASK);
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sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
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}
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}
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/*
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* notification of userspace execution resumption
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* - triggered by the TIF_WORK_MASK flags
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*/
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asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
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__u32 thread_info_flags)
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{
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/* deal with pending signal delivery */
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if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
|
|
current->thread.abi->do_signal(regs);
|
|
}
|