qemu/linux-user/sh4/signal.c

/*
 *  Emulation of Linux signals
 *
 *  Copyright (c) 2003 Fabrice Bellard
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */
#include "qemu/osdep.h"
#include "qemu.h"
#include "user-internals.h"
#include "signal-common.h"
#include "linux-user/trace.h"

/*
 * code and data structures from linux kernel:
 * include/asm-sh/sigcontext.h
 * arch/sh/kernel/signal.c
 */

struct target_sigcontext {
    target_ulong  oldmask;

    /* CPU registers */
    target_ulong  sc_gregs[16];
    target_ulong  sc_pc;
    target_ulong  sc_pr;
    target_ulong  sc_sr;
    target_ulong  sc_gbr;
    target_ulong  sc_mach;
    target_ulong  sc_macl;

    /* FPU registers */
    target_ulong  sc_fpregs[16];
    target_ulong  sc_xfpregs[16];
    unsigned int sc_fpscr;
    unsigned int sc_fpul;
    unsigned int sc_ownedfp;
};

struct target_sigframe
{
    struct target_sigcontext sc;
    target_ulong extramask[TARGET_NSIG_WORDS-1];
};


struct target_ucontext {
    target_ulong tuc_flags;
    struct target_ucontext *tuc_link;
    target_stack_t tuc_stack;
    struct target_sigcontext tuc_mcontext;
    target_sigset_t tuc_sigmask;        /* mask last for extensibility */
};

struct target_rt_sigframe
{
    struct target_siginfo info;
    struct target_ucontext uc;
};


#define MOVW(n)  (0x9300|((n)-2)) /* Move mem word at PC+n to R3 */
#define TRAP_NOARG 0xc310         /* Syscall w/no args (NR in R3) SH3/4 */

static abi_ulong get_sigframe(struct target_sigaction *ka,
                              unsigned long sp, size_t frame_size)
{
    sp = target_sigsp(sp, ka);

    return (sp - frame_size) & -8ul;
}

/*
 * Notice when we're in the middle of a gUSA region and reset.
 * Note that this will only occur when #CF_PARALLEL is unset, as we
 * will translate such sequences differently in a parallel context.
 */
static void unwind_gusa(CPUSH4State *regs)
{
    /* If the stack pointer is sufficiently negative, and we haven't
       completed the sequence, then reset to the entry to the region.  */
    /* ??? The SH4 kernel checks for and address above 0xC0000000.
       However, the page mappings in qemu linux-user aren't as restricted
       and we wind up with the normal stack mapped above 0xF0000000.
       That said, there is no reason why the kernel should be allowing
       a gUSA region that spans 1GB.  Use a tighter check here, for what
       can actually be enabled by the immediate move.  */
    if (regs->gregs[15] >= -128u && regs->pc < regs->gregs[0]) {
        /* Reset the PC to before the gUSA region, as computed from
           R0 = region end, SP = -(region size), plus one more for the
           insn that actually initializes SP to the region size.  */
        regs->pc = regs->gregs[0] + regs->gregs[15] - 2;

        /* Reset the SP to the saved version in R1.  */
        regs->gregs[15] = regs->gregs[1];
    } else if (regs->gregs[15] >= -128u && regs->pc == regs->gregs[0]) {
        /* If we are on the last instruction of a gUSA region, we must reset
           the SP, otherwise we would be pushing the signal context to
           invalid memory.  */
        regs->gregs[15] = regs->gregs[1];
    } else if (regs->flags & TB_FLAG_DELAY_SLOT) {
        /* If we are in a delay slot, push the previous instruction.  */
        regs->pc -= 2;
    }
}

static void setup_sigcontext(struct target_sigcontext *sc,
                             CPUSH4State *regs, unsigned long mask)
{
    int i;

#define COPY(x)         __put_user(regs->x, &sc->sc_##x)
    COPY(gregs[0]); COPY(gregs[1]);
    COPY(gregs[2]); COPY(gregs[3]);
    COPY(gregs[4]); COPY(gregs[5]);
    COPY(gregs[6]); COPY(gregs[7]);
    COPY(gregs[8]); COPY(gregs[9]);
    COPY(gregs[10]); COPY(gregs[11]);
    COPY(gregs[12]); COPY(gregs[13]);
    COPY(gregs[14]); COPY(gregs[15]);
    COPY(gbr); COPY(mach);
    COPY(macl); COPY(pr);
    COPY(sr); COPY(pc);
#undef COPY

    for (i=0; i<16; i++) {
        __put_user(regs->fregs[i], &sc->sc_fpregs[i]);
    }
    __put_user(regs->fpscr, &sc->sc_fpscr);
    __put_user(regs->fpul, &sc->sc_fpul);

    /* non-iBCS2 extensions.. */
    __put_user(mask, &sc->oldmask);
}

static void restore_sigcontext(CPUSH4State *regs, struct target_sigcontext *sc)
{
    int i;

#define COPY(x)         __get_user(regs->x, &sc->sc_##x)
    COPY(gregs[0]); COPY(gregs[1]);
    COPY(gregs[2]); COPY(gregs[3]);
    COPY(gregs[4]); COPY(gregs[5]);
    COPY(gregs[6]); COPY(gregs[7]);
    COPY(gregs[8]); COPY(gregs[9]);
    COPY(gregs[10]); COPY(gregs[11]);
    COPY(gregs[12]); COPY(gregs[13]);
    COPY(gregs[14]); COPY(gregs[15]);
    COPY(gbr); COPY(mach);
    COPY(macl); COPY(pr);
    COPY(sr); COPY(pc);
#undef COPY

    for (i=0; i<16; i++) {
        __get_user(regs->fregs[i], &sc->sc_fpregs[i]);
    }
    __get_user(regs->fpscr, &sc->sc_fpscr);
    __get_user(regs->fpul, &sc->sc_fpul);

    regs->tra = -1;         /* disable syscall checks */
    regs->flags = 0;
}

void setup_frame(int sig, struct target_sigaction *ka,
                 target_sigset_t *set, CPUSH4State *regs)
{
    struct target_sigframe *frame;
    abi_ulong frame_addr;
    int i;

    unwind_gusa(regs);

    frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
    trace_user_setup_frame(regs, frame_addr);
    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
        goto give_sigsegv;
    }

    setup_sigcontext(&frame->sc, regs, set->sig[0]);

    for (i = 0; i < TARGET_NSIG_WORDS - 1; i++) {
        __put_user(set->sig[i + 1], &frame->extramask[i]);
    }

    /* Set up to return from userspace.  If provided, use a stub
       already in userspace.  */
    if (ka->sa_flags & TARGET_SA_RESTORER) {
        regs->pr = ka->sa_restorer;
    } else {
        regs->pr = default_sigreturn;
    }

    /* Set up registers for signal handler */
    regs->gregs[15] = frame_addr;
    regs->gregs[4] = sig; /* Arg for signal handler */
    regs->gregs[5] = 0;
    regs->gregs[6] = frame_addr += offsetof(typeof(*frame), sc);
    regs->pc = (unsigned long) ka->_sa_handler;
    regs->flags &= ~(TB_FLAG_DELAY_SLOT_MASK | TB_FLAG_GUSA_MASK);

    unlock_user_struct(frame, frame_addr, 1);
    return;

give_sigsegv:
    unlock_user_struct(frame, frame_addr, 1);
    force_sigsegv(sig);
}

void setup_rt_frame(int sig, struct target_sigaction *ka,
                    target_siginfo_t *info,
                    target_sigset_t *set, CPUSH4State *regs)
{
    struct target_rt_sigframe *frame;
    abi_ulong frame_addr;
    int i;

    unwind_gusa(regs);

    frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
    trace_user_setup_rt_frame(regs, frame_addr);
    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
        goto give_sigsegv;
    }

    tswap_siginfo(&frame->info, info);

    /* Create the ucontext.  */
    __put_user(0, &frame->uc.tuc_flags);
    __put_user(0, (unsigned long *)&frame->uc.tuc_link);
    target_save_altstack(&frame->uc.tuc_stack, regs);
    setup_sigcontext(&frame->uc.tuc_mcontext,
                     regs, set->sig[0]);
    for(i = 0; i < TARGET_NSIG_WORDS; i++) {
        __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
    }

    /* Set up to return from userspace.  If provided, use a stub
       already in userspace.  */
    if (ka->sa_flags & TARGET_SA_RESTORER) {
        regs->pr = ka->sa_restorer;
    } else {
        regs->pr = default_rt_sigreturn;
    }

    /* Set up registers for signal handler */
    regs->gregs[15] = frame_addr;
    regs->gregs[4] = sig; /* Arg for signal handler */
    regs->gregs[5] = frame_addr + offsetof(typeof(*frame), info);
    regs->gregs[6] = frame_addr + offsetof(typeof(*frame), uc);
    regs->pc = (unsigned long) ka->_sa_handler;
    regs->flags &= ~(TB_FLAG_DELAY_SLOT_MASK | TB_FLAG_GUSA_MASK);

    unlock_user_struct(frame, frame_addr, 1);
    return;

give_sigsegv:
    unlock_user_struct(frame, frame_addr, 1);
    force_sigsegv(sig);
}

long do_sigreturn(CPUSH4State *regs)
{
    struct target_sigframe *frame;
    abi_ulong frame_addr;
    sigset_t blocked;
    target_sigset_t target_set;
    int i;

    frame_addr = regs->gregs[15];
    trace_user_do_sigreturn(regs, frame_addr);
    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
        goto badframe;
    }

    __get_user(target_set.sig[0], &frame->sc.oldmask);
    for(i = 1; i < TARGET_NSIG_WORDS; i++) {
        __get_user(target_set.sig[i], &frame->extramask[i - 1]);
    }

    target_to_host_sigset_internal(&blocked, &target_set);
    set_sigmask(&blocked);

    restore_sigcontext(regs, &frame->sc);

    unlock_user_struct(frame, frame_addr, 0);
    return -QEMU_ESIGRETURN;

badframe:
    unlock_user_struct(frame, frame_addr, 0);
    force_sig(TARGET_SIGSEGV);
    return -QEMU_ESIGRETURN;
}

long do_rt_sigreturn(CPUSH4State *regs)
{
    struct target_rt_sigframe *frame;
    abi_ulong frame_addr;
    sigset_t blocked;

    frame_addr = regs->gregs[15];
    trace_user_do_rt_sigreturn(regs, frame_addr);
    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
        goto badframe;
    }

    target_to_host_sigset(&blocked, &frame->uc.tuc_sigmask);
    set_sigmask(&blocked);

    restore_sigcontext(regs, &frame->uc.tuc_mcontext);
    target_restore_altstack(&frame->uc.tuc_stack, regs);

    unlock_user_struct(frame, frame_addr, 0);
    return -QEMU_ESIGRETURN;

badframe:
    unlock_user_struct(frame, frame_addr, 0);
    force_sig(TARGET_SIGSEGV);
    return -QEMU_ESIGRETURN;
}

void setup_sigtramp(abi_ulong sigtramp_page)
{
    uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 6, 0);
    assert(tramp != NULL);

    default_sigreturn = sigtramp_page;
    __put_user(MOVW(2), &tramp[0]);
    __put_user(TRAP_NOARG, &tramp[1]);
    __put_user(TARGET_NR_sigreturn, &tramp[2]);

    default_rt_sigreturn = sigtramp_page + 6;
    __put_user(MOVW(2), &tramp[3]);
    __put_user(TRAP_NOARG, &tramp[4]);
    __put_user(TARGET_NR_rt_sigreturn, &tramp[5]);

    unlock_user(tramp, sigtramp_page, 2 * 6);
}