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507 lines
12 KiB
507 lines
12 KiB
/* |
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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 <[email protected]> |
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* Joe Taylor <[email protected]> |
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*/ |
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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 pristine 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 = NO_SYSCALL; /* 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(void) |
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{ |
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struct pt_regs *regs = current_pt_regs(); |
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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(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); |
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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, ps; |
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unsigned int base; |
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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(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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ps = regs->ps; |
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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 if userspace uses windowed ABI */ |
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if (ps & PS_WOE_MASK) { |
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base = 4; |
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regs->areg[base] = |
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(((unsigned long) ra) & 0x3fffffff) | 0x40000000; |
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ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) | |
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(1 << PS_CALLINC_SHIFT); |
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} else { |
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base = 0; |
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regs->areg[base] = (unsigned long) ra; |
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} |
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regs->areg[base + 2] = (unsigned long) sig; |
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regs->areg[base + 3] = (unsigned long) &frame->info; |
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regs->areg[base + 4] = (unsigned long) &frame->uc; |
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regs->threadptr = tp; |
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regs->ps = ps; |
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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 (regs->syscall != NO_SYSCALL) { |
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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 (regs->syscall != NO_SYSCALL) { |
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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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test_thread_flag(TIF_NOTIFY_SIGNAL)) |
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do_signal(regs); |
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if (test_thread_flag(TIF_NOTIFY_RESUME)) |
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tracehook_notify_resume(regs); |
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}
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