qemu

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/*
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 *  Emulation of Linux signals
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 *
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 *  Copyright (c) 2003 Fabrice Bellard
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 *
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 *  This program is free software; you can redistribute it and/or modify
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 *  it under the terms of the GNU General Public License as published by
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 *  the Free Software Foundation; either version 2 of the License, or
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 *  (at your option) any later version.
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 *
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 *  This program is distributed in the hope that it will be useful,
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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 *  GNU General Public License for more details.
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 *
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 *  You should have received a copy of the GNU General Public License
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 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
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 */
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#include "qemu/osdep.h"
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#include "qemu.h"
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#include "user-internals.h"
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#include "signal-common.h"
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#include "linux-user/trace.h"
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#include "vdso-asmoffset.h"
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#define __NUM_GPRS 16
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#define __NUM_FPRS 16
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#define __NUM_ACRS 16
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#define _SIGCONTEXT_NSIG        64
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#define _SIGCONTEXT_NSIG_BPW    64 /* FIXME: 31-bit mode -> 32 */
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#define _SIGCONTEXT_NSIG_WORDS  (_SIGCONTEXT_NSIG / _SIGCONTEXT_NSIG_BPW)
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#define _SIGMASK_COPY_SIZE    (sizeof(unsigned long)*_SIGCONTEXT_NSIG_WORDS)
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#define S390_SYSCALL_OPCODE ((uint16_t)0x0a00)
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typedef struct {
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    target_psw_t psw;
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    abi_ulong gprs[__NUM_GPRS];
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    abi_uint acrs[__NUM_ACRS];
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} target_s390_regs_common;
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typedef struct {
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    uint32_t fpc;
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    uint32_t pad;
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    uint64_t fprs[__NUM_FPRS];
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} target_s390_fp_regs;
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typedef struct {
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    target_s390_regs_common regs;
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    target_s390_fp_regs     fpregs;
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} target_sigregs;
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typedef struct {
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    uint64_t vxrs_low[16];
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    uint64_t vxrs_high[16][2];
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    uint8_t reserved[128];
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} target_sigregs_ext;
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typedef struct {
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    abi_ulong oldmask[_SIGCONTEXT_NSIG_WORDS];
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    abi_ulong sregs;
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} target_sigcontext;
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typedef struct {
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    uint8_t callee_used_stack[STACK_FRAME_OVERHEAD];
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    target_sigcontext sc;
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    target_sigregs sregs;
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    int signo;
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    target_sigregs_ext sregs_ext;
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} sigframe;
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#define TARGET_UC_VXRS 2
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struct target_ucontext {
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    abi_ulong tuc_flags;
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    abi_ulong tuc_link;
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    target_stack_t tuc_stack;
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    target_sigregs tuc_mcontext;
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    target_sigset_t tuc_sigmask;
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    uint8_t reserved[128 - sizeof(target_sigset_t)];
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    target_sigregs_ext tuc_mcontext_ext;
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};
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typedef struct {
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    uint8_t callee_used_stack[STACK_FRAME_OVERHEAD];
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    /*
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     * This field is no longer initialized by the kernel, but it's still a part
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     * of the ABI.
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     */
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    uint16_t svc_insn;
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    struct target_siginfo info;
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    struct target_ucontext uc;
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} rt_sigframe;
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static inline abi_ulong
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get_sigframe(struct target_sigaction *ka, CPUS390XState *env, size_t frame_size)
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{
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    abi_ulong sp;
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    /* Default to using normal stack */
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    sp = get_sp_from_cpustate(env);
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    /* This is the X/Open sanctioned signal stack switching.  */
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    if (ka->sa_flags & TARGET_SA_ONSTACK) {
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        sp = target_sigsp(sp, ka);
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    }
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    /* This is the legacy signal stack switching. */
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    else if (/* FIXME !user_mode(regs) */ 0 &&
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             !(ka->sa_flags & TARGET_SA_RESTORER) &&
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             ka->sa_restorer) {
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        sp = (abi_ulong) ka->sa_restorer;
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    }
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    return (sp - frame_size) & -8ul;
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}
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#define PSW_USER_BITS   (PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | \
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                         PSW_MASK_MCHECK | PSW_MASK_PSTATE | PSW_ASC_PRIMARY)
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#define PSW_MASK_USER   (PSW_MASK_ASC | PSW_MASK_CC | PSW_MASK_PM | \
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                         PSW_MASK_64 | PSW_MASK_32)
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static void save_sigregs(CPUS390XState *env, target_sigregs *sregs)
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{
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    uint64_t psw_mask = s390_cpu_get_psw_mask(env);
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    int i;
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    /*
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     * Copy a 'clean' PSW mask to the user to avoid leaking
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     * information about whether PER is currently on.
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     * TODO: qemu does not support PSW_MASK_RI; it will never be set.
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     */
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    psw_mask = PSW_USER_BITS | (psw_mask & PSW_MASK_USER);
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    __put_user(psw_mask, &sregs->regs.psw.mask);
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    __put_user(env->psw.addr, &sregs->regs.psw.addr);
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    for (i = 0; i < 16; i++) {
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        __put_user(env->regs[i], &sregs->regs.gprs[i]);
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    }
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    for (i = 0; i < 16; i++) {
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        __put_user(env->aregs[i], &sregs->regs.acrs[i]);
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    }
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    /*
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     * We have to store the fp registers to current->thread.fp_regs
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     * to merge them with the emulated registers.
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     */
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    __put_user(env->fpc, &sregs->fpregs.fpc);
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    for (i = 0; i < 16; i++) {
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        __put_user(*get_freg(env, i), &sregs->fpregs.fprs[i]);
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    }
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}
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static void save_sigregs_ext(CPUS390XState *env, target_sigregs_ext *ext)
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{
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    int i;
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    /*
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     * if (MACHINE_HAS_VX) ...
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     * That said, we always allocate the stack storage and the
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     * space is always available in env.
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     */
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    for (i = 0; i < 16; ++i) {
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        __put_user(env->vregs[i][1], &ext->vxrs_low[i]);
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    }
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    for (i = 0; i < 16; ++i) {
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        __put_user(env->vregs[i + 16][0], &ext->vxrs_high[i][0]);
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        __put_user(env->vregs[i + 16][1], &ext->vxrs_high[i][1]);
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    }
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}
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void setup_frame(int sig, struct target_sigaction *ka,
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                 target_sigset_t *set, CPUS390XState *env)
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{
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    sigframe *frame;
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    abi_ulong frame_addr;
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    abi_ulong restorer;
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    frame_addr = get_sigframe(ka, env, sizeof(*frame));
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    trace_user_setup_frame(env, frame_addr);
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    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
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        force_sigsegv(sig);
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        return;
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    }
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    /* Set up backchain. */
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    __put_user(env->regs[15], (abi_ulong *) frame);
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    /* Create struct sigcontext on the signal stack. */
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    /* Make sure that we're initializing all of oldmask. */
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    QEMU_BUILD_BUG_ON(ARRAY_SIZE(frame->sc.oldmask) != 1);
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    __put_user(set->sig[0], &frame->sc.oldmask[0]);
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    __put_user(frame_addr + offsetof(sigframe, sregs), &frame->sc.sregs);
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    /* Create _sigregs on the signal stack */
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    save_sigregs(env, &frame->sregs);
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    /*
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     * ??? The kernel uses regs->gprs[2] here, which is not yet the signo.
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     * Moreover the comment talks about allowing backtrace, which is really
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     * done by the r15 copy above.
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     */
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    __put_user(sig, &frame->signo);
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    /* Create sigregs_ext on the signal stack. */
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    save_sigregs_ext(env, &frame->sregs_ext);
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    /*
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     * Set up to return from userspace.
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     * If provided, use a stub already in userspace.
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     */
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    if (ka->sa_flags & TARGET_SA_RESTORER) {
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        restorer = ka->sa_restorer;
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    } else {
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        restorer = default_sigreturn;
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    }
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    /* Set up registers for signal handler */
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    env->regs[14] = restorer;
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    env->regs[15] = frame_addr;
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    /* Force default amode and default user address space control. */
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    env->psw.mask = PSW_MASK_64 | PSW_MASK_32 | PSW_ASC_PRIMARY
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                  | (env->psw.mask & ~PSW_MASK_ASC);
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    env->psw.addr = ka->_sa_handler;
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    env->regs[2] = sig;
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    env->regs[3] = frame_addr + offsetof(typeof(*frame), sc);
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    /*
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     * We forgot to include these in the sigcontext.
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     * To avoid breaking binary compatibility, they are passed as args.
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     */
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    env->regs[4] = 0; /* FIXME: regs->int_code & 127 */
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    env->regs[5] = 0; /* FIXME: regs->int_parm_long */
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    env->regs[6] = 0; /* FIXME: current->thread.last_break */
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    unlock_user_struct(frame, frame_addr, 1);
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}
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void setup_rt_frame(int sig, struct target_sigaction *ka,
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                    target_siginfo_t *info,
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                    target_sigset_t *set, CPUS390XState *env)
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{
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    rt_sigframe *frame;
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    abi_ulong frame_addr;
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    abi_ulong restorer;
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    abi_ulong uc_flags;
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    frame_addr = get_sigframe(ka, env, sizeof *frame);
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    trace_user_setup_rt_frame(env, frame_addr);
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    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
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        force_sigsegv(sig);
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        return;
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    }
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    /* Set up backchain. */
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    __put_user(env->regs[15], (abi_ulong *) frame);
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    /*
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     * Set up to return from userspace.
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     * If provided, use a stub already in userspace.
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     */
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    if (ka->sa_flags & TARGET_SA_RESTORER) {
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        restorer = ka->sa_restorer;
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    } else {
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        restorer = default_rt_sigreturn;
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    }
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    /* Create siginfo on the signal stack. */
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    frame->info = *info;
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    /* Create ucontext on the signal stack. */
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    uc_flags = 0;
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    if (s390_has_feat(S390_FEAT_VECTOR)) {
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        uc_flags |= TARGET_UC_VXRS;
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    }
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    __put_user(uc_flags, &frame->uc.tuc_flags);
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    __put_user(0, &frame->uc.tuc_link);
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    target_save_altstack(&frame->uc.tuc_stack, env);
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    save_sigregs(env, &frame->uc.tuc_mcontext);
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    save_sigregs_ext(env, &frame->uc.tuc_mcontext_ext);
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    tswap_sigset(&frame->uc.tuc_sigmask, set);
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    /* Set up registers for signal handler */
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    env->regs[14] = restorer;
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    env->regs[15] = frame_addr;
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    /* Force default amode and default user address space control. */
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    env->psw.mask = PSW_MASK_64 | PSW_MASK_32 | PSW_ASC_PRIMARY
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                  | (env->psw.mask & ~PSW_MASK_ASC);
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    env->psw.addr = ka->_sa_handler;
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    env->regs[2] = sig;
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    env->regs[3] = frame_addr + offsetof(typeof(*frame), info);
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    env->regs[4] = frame_addr + offsetof(typeof(*frame), uc);
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    env->regs[5] = 0; /* FIXME: current->thread.last_break */
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}
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static void restore_sigregs(CPUS390XState *env, target_sigregs *sc)
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{
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    uint64_t prev_addr, prev_mask, mask, addr;
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    int i;
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    for (i = 0; i < 16; i++) {
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        __get_user(env->regs[i], &sc->regs.gprs[i]);
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    }
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    prev_addr = env->psw.addr;
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    __get_user(mask, &sc->regs.psw.mask);
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    __get_user(addr, &sc->regs.psw.addr);
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    trace_user_s390x_restore_sigregs(env, addr, prev_addr);
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    /*
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     * Use current psw.mask to preserve PER bit.
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     * TODO:
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     *  if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
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     *          return -EINVAL;
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     * Simply do not allow it to be set in mask.
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     */
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    prev_mask = s390_cpu_get_psw_mask(env);
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    mask = (prev_mask & ~PSW_MASK_USER) | (mask & PSW_MASK_USER);
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    /* Check for invalid user address space control. */
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    if ((mask & PSW_MASK_ASC) == PSW_ASC_HOME) {
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        mask = (mask & ~PSW_MASK_ASC) | PSW_ASC_PRIMARY;
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    }
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    /* Check for invalid amode. */
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    if (mask & PSW_MASK_64) {
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        mask |= PSW_MASK_32;
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    }
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    s390_cpu_set_psw(env, mask, addr);
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    for (i = 0; i < 16; i++) {
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        __get_user(env->aregs[i], &sc->regs.acrs[i]);
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    }
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    __get_user(env->fpc, &sc->fpregs.fpc);
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    for (i = 0; i < 16; i++) {
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        __get_user(*get_freg(env, i), &sc->fpregs.fprs[i]);
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    }
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}
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static void restore_sigregs_ext(CPUS390XState *env, target_sigregs_ext *ext)
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{
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    int i;
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    /*
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     * if (MACHINE_HAS_VX) ...
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     * That said, we always allocate the stack storage and the
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     * space is always available in env.
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     */
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    for (i = 0; i < 16; ++i) {
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        __get_user(env->vregs[i][1], &ext->vxrs_low[i]);
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    }
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    for (i = 0; i < 16; ++i) {
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        __get_user(env->vregs[i + 16][0], &ext->vxrs_high[i][0]);
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        __get_user(env->vregs[i + 16][1], &ext->vxrs_high[i][1]);
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    }
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}
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long do_sigreturn(CPUS390XState *env)
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{
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    sigframe *frame;
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    abi_ulong frame_addr = env->regs[15];
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    target_sigset_t target_set;
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    sigset_t set;
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    trace_user_do_sigreturn(env, frame_addr);
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    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
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        force_sig(TARGET_SIGSEGV);
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        return -QEMU_ESIGRETURN;
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    }
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    /* Make sure that we're initializing all of target_set. */
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    QEMU_BUILD_BUG_ON(ARRAY_SIZE(target_set.sig) != 1);
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    __get_user(target_set.sig[0], &frame->sc.oldmask[0]);
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    target_to_host_sigset_internal(&set, &target_set);
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    set_sigmask(&set); /* ~_BLOCKABLE? */
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    restore_sigregs(env, &frame->sregs);
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    restore_sigregs_ext(env, &frame->sregs_ext);
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    unlock_user_struct(frame, frame_addr, 0);
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    return -QEMU_ESIGRETURN;
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}
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long do_rt_sigreturn(CPUS390XState *env)
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{
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    rt_sigframe *frame;
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    abi_ulong frame_addr = env->regs[15];
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    sigset_t set;
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    trace_user_do_rt_sigreturn(env, frame_addr);
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    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
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        force_sig(TARGET_SIGSEGV);
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        return -QEMU_ESIGRETURN;
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    }
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    target_to_host_sigset(&set, &frame->uc.tuc_sigmask);
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    set_sigmask(&set); /* ~_BLOCKABLE? */
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    restore_sigregs(env, &frame->uc.tuc_mcontext);
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    restore_sigregs_ext(env, &frame->uc.tuc_mcontext_ext);
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    target_restore_altstack(&frame->uc.tuc_stack, env);
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    unlock_user_struct(frame, frame_addr, 0);
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    return -QEMU_ESIGRETURN;
407
}
408

409
void setup_sigtramp(abi_ulong sigtramp_page)
410
{
411
    uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 + 2, 0);
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    assert(tramp != NULL);
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    default_sigreturn = sigtramp_page;
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    __put_user(S390_SYSCALL_OPCODE | TARGET_NR_sigreturn, &tramp[0]);
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    default_rt_sigreturn = sigtramp_page + 2;
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    __put_user(S390_SYSCALL_OPCODE | TARGET_NR_rt_sigreturn, &tramp[1]);
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    unlock_user(tramp, sigtramp_page, 2 + 2);
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}
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