![Linus Torvalds](/assets/img/avatar_default.png)
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument of the user address range verification function since we got rid of the old racy i386-only code to walk page tables by hand. It existed because the original 80386 would not honor the write protect bit when in kernel mode, so you had to do COW by hand before doing any user access. But we haven't supported that in a long time, and these days the 'type' argument is a purely historical artifact. A discussion about extending 'user_access_begin()' to do the range checking resulted this patch, because there is no way we're going to move the old VERIFY_xyz interface to that model. And it's best done at the end of the merge window when I've done most of my merges, so let's just get this done once and for all. This patch was mostly done with a sed-script, with manual fix-ups for the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form. There were a couple of notable cases: - csky still had the old "verify_area()" name as an alias. - the iter_iov code had magical hardcoded knowledge of the actual values of VERIFY_{READ,WRITE} (not that they mattered, since nothing really used it) - microblaze used the type argument for a debug printout but other than those oddities this should be a total no-op patch. I tried to fix up all architectures, did fairly extensive grepping for access_ok() uses, and the changes are trivial, but I may have missed something. Any missed conversion should be trivially fixable, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
497 lines
12 KiB
C
497 lines
12 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/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(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(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(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 (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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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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