forked from Minki/linux
29c4dfd92e
The non-rt signal handling was never really used, so we don't break anything. This patch also cleans up the signal stack-frame to make it independent from the processor configuration. It also improves the method used for controlling single-stepping. We now save and restore the 'icountlevel' register that controls single stepping and set or clear the saved state to enable or disable it. Signed-off-by: Chris Zankel <chris@zankel.net>
557 lines
13 KiB
C
557 lines
13 KiB
C
/*
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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/freezer.h>
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#include <asm/ucontext.h>
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#include <asm/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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#define DEBUG_SIG 0
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#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
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asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
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extern struct task_struct *coproc_owners[];
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extern void release_all_cp (struct task_struct *);
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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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cp_state_t cpstate;
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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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* Note that windowbase, windowstart, and wmask are not updated!
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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((void*)(sp - 32),
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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((void*)(sp - 48),
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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((void*)(sp - 16), ®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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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 sigcontext __user *sc, cp_state_t *cpstate,
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struct pt_regs *regs, unsigned long mask)
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{
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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 |= __copy_to_user (sc->sc_a, regs->areg, XCHAL_NUM_AREGS * 4)
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#if XCHAL_HAVE_CP
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# error Coprocessors unsupported
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err |= save_cpextra(cpstate);
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err |= __put_user(err ? NULL : cpstate, &sc->sc_cpstate);
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#endif
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/* non-iBCS2 extensions.. */
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err |= __put_user(mask, &sc->oldmask);
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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 sigcontext __user *sc)
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{
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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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/* 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 XCHAL_HAVE_CP
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# error Coprocessors unsupported
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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 (!err) {
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struct task_struct *tsk = current;
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release_all_cp(tsk);
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err |= __copy_from_user(tsk->thread.cpextra, sc->sc_cpstate,
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XTENSA_CP_EXTRA_SIZE);
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}
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#endif
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regs->syscall = -1; /* disable syscall checks */
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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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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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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(regs, &frame->uc.uc_mcontext))
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goto badframe;
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ret = regs->areg[2];
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if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->areg[1]) == -EFAULT)
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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 void setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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sigset_t *set, struct pt_regs *regs)
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{
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struct rt_sigframe *frame;
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int err = 0;
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int signal;
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unsigned long sp, ra;
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sp = regs->areg[1];
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if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) {
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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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goto give_sigsegv;
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}
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signal = current_thread_info()->exec_domain
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&& current_thread_info()->exec_domain->signal_invmap
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&& sig < 32
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? current_thread_info()->exec_domain->signal_invmap[sig]
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: sig;
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if (ka->sa.sa_flags & SA_SIGINFO) {
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err |= copy_siginfo_to_user(&frame->info, 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 |= __put_user((void *)current->sas_ss_sp,
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&frame->uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->areg[1]),
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&frame->uc.uc_stack.ss_flags);
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err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->cpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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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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goto give_sigsegv;
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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 */
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start_thread(regs, (unsigned long) 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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ra = (unsigned long) frame->retcode;
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regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
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regs->areg[6] = (unsigned long) signal;
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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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/* Set access mode to USER_DS. Nomenclature is outdated, but
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* functionality is used in uaccess.h
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*/
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set_fs(USER_DS);
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#if DEBUG_SIG
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printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
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current->comm, current->pid, signal, frame, regs->pc);
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#endif
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return;
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give_sigsegv:
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if (sig == SIGSEGV)
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ka->sa.sa_handler = SIG_DFL;
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force_sig(SIGSEGV, current);
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}
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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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asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset,
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size_t sigsetsize,
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long a2, long a3, long a4, long a5,
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struct pt_regs *regs)
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{
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sigset_t saveset, newset;
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/* XXX: Don't preclude handling different sized sigset_t's. */
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if (sigsetsize != sizeof(sigset_t))
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return -EINVAL;
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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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saveset = 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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regs->areg[2] = -EINTR;
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while (1) {
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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if (do_signal(regs, &saveset))
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return -EINTR;
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}
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}
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asmlinkage long xtensa_sigaltstack(const stack_t __user *uss,
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stack_t __user *uoss,
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long a2, long a3, long a4, long a5,
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struct pt_regs *regs)
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{
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return do_sigaltstack(uss, uoss, regs->areg[1]);
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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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int do_signal(struct pt_regs *regs, sigset_t *oldset)
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{
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siginfo_t info;
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int signr;
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struct k_sigaction ka;
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if (!user_mode(regs))
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return 0;
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if (try_to_freeze())
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goto no_signal;
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if (!oldset)
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oldset = ¤t->blocked;
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task_pt_regs(current)->icountlevel = 0;
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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if (signr > 0) {
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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 (!(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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setup_frame(signr, &ka, &info, oldset, regs);
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if (ka.sa.sa_flags & SA_ONESHOT)
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ka.sa.sa_handler = SIG_DFL;
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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, signr);
|
|
recalc_sigpending();
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
if (current->ptrace & PT_SINGLESTEP)
|
|
task_pt_regs(current)->icountlevel = 1;
|
|
|
|
return 1;
|
|
}
|
|
|
|
no_signal:
|
|
/* Did we come from a system call? */
|
|
if ((signed) regs->syscall >= 0) {
|
|
/* Restart the system call - no handlers present */
|
|
switch (regs->areg[2]) {
|
|
case -ERESTARTNOHAND:
|
|
case -ERESTARTSYS:
|
|
case -ERESTARTNOINTR:
|
|
regs->areg[2] = regs->syscall;
|
|
regs->pc -= 3;
|
|
break;
|
|
case -ERESTART_RESTARTBLOCK:
|
|
regs->areg[2] = __NR_restart_syscall;
|
|
regs->pc -= 3;
|
|
break;
|
|
}
|
|
}
|
|
if (current->ptrace & PT_SINGLESTEP)
|
|
task_pt_regs(current)->icountlevel = 1;
|
|
return 0;
|
|
}
|
|
|