/*
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* arch/xtensa/kernel/signal.c
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*
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* Default platform functions.
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*
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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) 2005, 2006 Tensilica Inc.
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* Copyright (C) 1991, 1992 Linus Torvalds
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* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
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*
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* Chris Zankel <chris@zankel.net>
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* Joe Taylor <joe@tensilica.com>
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*/
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/ptrace.h>
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#include <linux/personality.h>
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#include <linux/tracehook.h>
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#include <linux/sched/task_stack.h>
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#include <asm/ucontext.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/coprocessor.h>
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#include <asm/unistd.h>
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extern struct task_struct *coproc_owners[];
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struct rt_sigframe
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{
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struct siginfo info;
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struct ucontext uc;
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struct {
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xtregs_opt_t opt;
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xtregs_user_t user;
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#if XTENSA_HAVE_COPROCESSORS
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xtregs_coprocessor_t cp;
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#endif
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} xtregs;
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unsigned char retcode[6];
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unsigned int window[4];
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};
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/*
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* Flush register windows stored in pt_regs to stack.
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* Returns 1 for errors.
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*/
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int
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flush_window_regs_user(struct pt_regs *regs)
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{
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const unsigned long ws = regs->windowstart;
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const unsigned long wb = regs->windowbase;
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unsigned long sp = 0;
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unsigned long wm;
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int err = 1;
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int base;
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/* Return if no other frames. */
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if (regs->wmask == 1)
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return 0;
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/* Rotate windowmask and skip empty frames. */
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wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
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base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
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/* For call8 or call12 frames, we need the previous stack pointer. */
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if ((regs->wmask & 2) == 0)
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if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
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goto errout;
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/* Spill frames to stack. */
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while (base < XCHAL_NUM_AREGS / 4) {
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int m = (wm >> base);
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int inc = 0;
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/* Save registers a4..a7 (call8) or a4...a11 (call12) */
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if (m & 2) { /* call4 */
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inc = 1;
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} else if (m & 4) { /* call8 */
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if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4),
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®s->areg[(base + 1) * 4], 16))
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goto errout;
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inc = 2;
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} else if (m & 8) { /* call12 */
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if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4),
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®s->areg[(base + 1) * 4], 32))
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goto errout;
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inc = 3;
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}
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/* Save current frame a0..a3 under next SP */
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sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
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if (copy_to_user(&SPILL_SLOT(sp, 0), ®s->areg[base * 4], 16))
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goto errout;
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/* Get current stack pointer for next loop iteration. */
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sp = regs->areg[base * 4 + 1];
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base += inc;
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}
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regs->wmask = 1;
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regs->windowstart = 1 << wb;
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return 0;
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errout:
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return err;
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}
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/*
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* Note: We don't copy double exception 'regs', we have to finish double exc.
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* first before we return to signal handler! This dbl.exc.handler might cause
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* another double exception, but I think we are fine as the situation is the
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* same as if we had returned to the signal handerl and got an interrupt
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* immediately...
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*/
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static int
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setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
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{
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struct sigcontext __user *sc = &frame->uc.uc_mcontext;
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struct thread_info *ti = current_thread_info();
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int err = 0;
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#define COPY(x) err |= __put_user(regs->x, &sc->sc_##x)
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COPY(pc);
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COPY(ps);
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COPY(lbeg);
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COPY(lend);
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COPY(lcount);
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COPY(sar);
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#undef COPY
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err |= flush_window_regs_user(regs);
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err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
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err |= __put_user(0, &sc->sc_xtregs);
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if (err)
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return err;
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#if XTENSA_HAVE_COPROCESSORS
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coprocessor_flush_all(ti);
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coprocessor_release_all(ti);
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err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
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sizeof (frame->xtregs.cp));
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#endif
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err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt,
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sizeof (xtregs_opt_t));
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err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
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sizeof (xtregs_user_t));
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err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);
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return err;
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}
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static int
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restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
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{
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struct sigcontext __user *sc = &frame->uc.uc_mcontext;
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struct thread_info *ti = current_thread_info();
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unsigned int err = 0;
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unsigned long ps;
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#define COPY(x) err |= __get_user(regs->x, &sc->sc_##x)
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COPY(pc);
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COPY(lbeg);
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COPY(lend);
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COPY(lcount);
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COPY(sar);
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#undef COPY
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/* All registers were flushed to stack. Start with a prestine frame. */
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regs->wmask = 1;
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regs->windowbase = 0;
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regs->windowstart = 1;
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regs->syscall = -1; /* disable syscall checks */
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/* For PS, restore only PS.CALLINC.
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* Assume that all other bits are either the same as for the signal
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* handler, or the user mode value doesn't matter (e.g. PS.OWB).
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*/
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err |= __get_user(ps, &sc->sc_ps);
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regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);
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/* Additional corruption checks */
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if ((regs->lcount > 0)
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&& ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
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err = 1;
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err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);
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if (err)
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return err;
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/* The signal handler may have used coprocessors in which
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* case they are still enabled. We disable them to force a
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* reloading of the original task's CP state by the lazy
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* context-switching mechanisms of CP exception handling.
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* Also, we essentially discard any coprocessor state that the
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* signal handler created. */
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#if XTENSA_HAVE_COPROCESSORS
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coprocessor_release_all(ti);
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err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
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sizeof (frame->xtregs.cp));
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#endif
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err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
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sizeof (xtregs_user_t));
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err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt,
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sizeof (xtregs_opt_t));
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return err;
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}
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/*
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* Do a signal return; undo the signal stack.
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*/
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asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3,
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long a4, long a5, 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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int ret;
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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if (regs->depc > 64)
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panic("rt_sigreturn in double exception!\n");
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frame = (struct rt_sigframe __user *) regs->areg[1];
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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->uc.uc_sigmask, sizeof(set)))
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goto badframe;
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set_current_blocked(&set);
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if (restore_sigcontext(regs, frame))
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goto badframe;
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ret = regs->areg[2];
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if (restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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return ret;
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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/*
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* Set up a signal frame.
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*/
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static int
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gen_return_code(unsigned char *codemem)
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{
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int err = 0;
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/*
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* The 12-bit immediate is really split up within the 24-bit MOVI
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* instruction. As long as the above system call numbers fit within
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* 8-bits, the following code works fine. See the Xtensa ISA for
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* details.
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*/
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#if __NR_rt_sigreturn > 255
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# error Generating the MOVI instruction below breaks!
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#endif
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#ifdef __XTENSA_EB__ /* Big Endian version */
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/* Generate instruction: MOVI a2, __NR_rt_sigreturn */
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err |= __put_user(0x22, &codemem[0]);
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err |= __put_user(0x0a, &codemem[1]);
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err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
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/* Generate instruction: SYSCALL */
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err |= __put_user(0x00, &codemem[3]);
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err |= __put_user(0x05, &codemem[4]);
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err |= __put_user(0x00, &codemem[5]);
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#elif defined __XTENSA_EL__ /* Little Endian version */
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/* Generate instruction: MOVI a2, __NR_rt_sigreturn */
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err |= __put_user(0x22, &codemem[0]);
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err |= __put_user(0xa0, &codemem[1]);
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err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
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/* Generate instruction: SYSCALL */
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err |= __put_user(0x00, &codemem[3]);
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err |= __put_user(0x50, &codemem[4]);
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err |= __put_user(0x00, &codemem[5]);
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#else
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# error Must use compiler for Xtensa processors.
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#endif
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/* Flush generated code out of the data cache */
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if (err == 0) {
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__invalidate_icache_range((unsigned long)codemem, 6UL);
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__flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
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}
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return err;
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}
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static int setup_frame(struct ksignal *ksig, sigset_t *set,
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struct pt_regs *regs)
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{
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struct rt_sigframe *frame;
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int err = 0, sig = ksig->sig;
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unsigned long sp, ra, tp;
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sp = regs->areg[1];
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if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) {
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sp = current->sas_ss_sp + current->sas_ss_size;
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}
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frame = (void *)((sp - sizeof(*frame)) & -16ul);
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if (regs->depc > 64)
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panic ("Double exception sys_sigreturn\n");
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) {
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return -EFAULT;
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}
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if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
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err |= copy_siginfo_to_user(&frame->info, &ksig->info);
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}
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/* Create the user context. */
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(0, &frame->uc.uc_link);
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err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]);
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err |= setup_sigcontext(frame, regs);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (ksig->ka.sa.sa_flags & SA_RESTORER) {
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ra = (unsigned long)ksig->ka.sa.sa_restorer;
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} else {
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/* Create sys_rt_sigreturn syscall in stack frame */
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err |= gen_return_code(frame->retcode);
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if (err) {
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return -EFAULT;
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}
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ra = (unsigned long) frame->retcode;
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}
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/*
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* Create signal handler execution context.
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* Return context not modified until this point.
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*/
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/* Set up registers for signal handler; preserve the threadptr */
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tp = regs->threadptr;
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start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler,
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(unsigned long) frame);
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/* Set up a stack frame for a call4
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* Note: PS.CALLINC is set to one by start_thread
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*/
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regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
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regs->areg[6] = (unsigned long) sig;
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regs->areg[7] = (unsigned long) &frame->info;
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regs->areg[8] = (unsigned long) &frame->uc;
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regs->threadptr = tp;
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pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n",
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current->comm, current->pid, sig, frame, regs->pc);
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return 0;
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}
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/*
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* Note that 'init' is a special process: it doesn't get signals it doesn't
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* want to handle. Thus you cannot kill init even with a SIGKILL even by
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* mistake.
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*
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* Note that we go through the signals twice: once to check the signals that
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* the kernel can handle, and then we build all the user-level signal handling
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* stack-frames in one go after that.
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*/
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static void do_signal(struct pt_regs *regs)
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{
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struct ksignal ksig;
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task_pt_regs(current)->icountlevel = 0;
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if (get_signal(&ksig)) {
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int ret;
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/* Are we from a system call? */
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if ((signed)regs->syscall >= 0) {
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/* If so, check system call restarting.. */
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switch (regs->areg[2]) {
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case -ERESTARTNOHAND:
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case -ERESTART_RESTARTBLOCK:
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regs->areg[2] = -EINTR;
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break;
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case -ERESTARTSYS:
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if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
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regs->areg[2] = -EINTR;
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break;
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}
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/* fallthrough */
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case -ERESTARTNOINTR:
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regs->areg[2] = regs->syscall;
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regs->pc -= 3;
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break;
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default:
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/* nothing to do */
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if (regs->areg[2] != 0)
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break;
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}
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}
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/* Whee! Actually deliver the signal. */
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/* Set up the stack frame */
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ret = setup_frame(&ksig, sigmask_to_save(), regs);
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signal_setup_done(ret, &ksig, 0);
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if (current->ptrace & PT_SINGLESTEP)
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task_pt_regs(current)->icountlevel = 1;
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return;
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}
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/* Did we come from a system call? */
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if ((signed) regs->syscall >= 0) {
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/* Restart the system call - no handlers present */
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switch (regs->areg[2]) {
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case -ERESTARTNOHAND:
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case -ERESTARTSYS:
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case -ERESTARTNOINTR:
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regs->areg[2] = regs->syscall;
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regs->pc -= 3;
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break;
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case -ERESTART_RESTARTBLOCK:
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regs->areg[2] = __NR_restart_syscall;
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regs->pc -= 3;
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break;
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}
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}
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/* If there's no signal to deliver, we just restore the saved mask. */
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restore_saved_sigmask();
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if (current->ptrace & PT_SINGLESTEP)
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task_pt_regs(current)->icountlevel = 1;
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return;
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}
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void do_notify_resume(struct pt_regs *regs)
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{
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if (test_thread_flag(TIF_SIGPENDING))
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do_signal(regs);
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if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
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tracehook_notify_resume(regs);
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}
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