qemu-qemu/bsd-user/arm/signal.c

/*
 * arm signal functions
 *
 * Copyright (c) 2013 Stacey D. Son
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */
#include "qemu/osdep.h"
#include "qemu.h"

/*
 * Compare to arm/arm/machdep.c sendsig()
 * Assumes that target stack frame memory is locked.
 */
abi_long set_sigtramp_args(CPUARMState *env, int sig,
                           struct target_sigframe *frame,
                           abi_ulong frame_addr,
                           struct target_sigaction *ka)
{
    /*
     * Arguments to signal handler:
     *  r0 = signal number
     *  r1 = siginfo pointer
     *  r2 = ucontext pointer
     *  r5 = ucontext pointer
     *  pc = signal handler pointer
     *  sp = sigframe struct pointer
     *  lr = sigtramp at base of user stack
     */

    env->regs[0] = sig;
    env->regs[1] = frame_addr +
        offsetof(struct target_sigframe, sf_si);
    env->regs[2] = frame_addr +
        offsetof(struct target_sigframe, sf_uc);

    /* the trampoline uses r5 as the uc address */
    env->regs[5] = frame_addr +
        offsetof(struct target_sigframe, sf_uc);
    env->regs[TARGET_REG_PC] = ka->_sa_handler & ~1;
    env->regs[TARGET_REG_SP] = frame_addr;
    env->regs[TARGET_REG_LR] = TARGET_PS_STRINGS - TARGET_SZSIGCODE;
    /*
     * Low bit indicates whether or not we're entering thumb mode.
     */
    cpsr_write(env, (ka->_sa_handler & 1) * CPSR_T, CPSR_T, CPSRWriteByInstr);

    return 0;
}

static abi_long get_vfpcontext(CPUARMState *env, abi_ulong frame_addr,
                               struct target_sigframe *frame)
{
    /* see sendsig and get_vfpcontext in sys/arm/arm/exec_machdep.c */
    target_mcontext_vfp_t *vfp = &frame->sf_vfp;
    target_mcontext_t *mcp = &frame->sf_uc.uc_mcontext;

    /* Assumes that mcp and vfp are locked */
    for (int i = 0; i < 32; i++) {
        vfp->mcv_reg[i] = tswap64(*aa32_vfp_dreg(env, i));
    }
    vfp->mcv_fpscr = tswap32(vfp_get_fpscr(env));
    mcp->mc_vfp_size = tswap32(sizeof(*vfp));
    mcp->mc_vfp_ptr = tswap32(frame_addr + ((uintptr_t)vfp - (uintptr_t)frame));
    return 0;
}

/*
 * Compare to arm/arm/exec_machdep.c get_mcontext()
 * Assumes that the memory is locked if mcp points to user memory.
 */
abi_long get_mcontext(CPUARMState *env, target_mcontext_t *mcp, int flags)
{
    uint32_t *gr = mcp->__gregs;

    gr[TARGET_REG_CPSR] = tswap32(cpsr_read(env));
    if (flags & TARGET_MC_GET_CLEAR_RET) {
        gr[TARGET_REG_R0] = 0;
        gr[TARGET_REG_CPSR] &= ~CPSR_C;
    } else {
        gr[TARGET_REG_R0] = tswap32(env->regs[0]);
    }

    gr[TARGET_REG_R1] = tswap32(env->regs[1]);
    gr[TARGET_REG_R2] = tswap32(env->regs[2]);
    gr[TARGET_REG_R3] = tswap32(env->regs[3]);
    gr[TARGET_REG_R4] = tswap32(env->regs[4]);
    gr[TARGET_REG_R5] = tswap32(env->regs[5]);
    gr[TARGET_REG_R6] = tswap32(env->regs[6]);
    gr[TARGET_REG_R7] = tswap32(env->regs[7]);
    gr[TARGET_REG_R8] = tswap32(env->regs[8]);
    gr[TARGET_REG_R9] = tswap32(env->regs[9]);
    gr[TARGET_REG_R10] = tswap32(env->regs[10]);
    gr[TARGET_REG_R11] = tswap32(env->regs[11]);
    gr[TARGET_REG_R12] = tswap32(env->regs[12]);

    gr[TARGET_REG_SP] = tswap32(env->regs[13]);
    gr[TARGET_REG_LR] = tswap32(env->regs[14]);
    gr[TARGET_REG_PC] = tswap32(env->regs[15]);

    /*
     * FreeBSD's get_mcontext doesn't save VFP info, but sets the pointer and
     * size to zero.  Applications that need the VFP state use
     * sysarch(ARM_GET_VFPSTATE) and are expected to adjust mcontext after that.
     */
    mcp->mc_vfp_size = 0;
    mcp->mc_vfp_ptr = 0;
    memset(&mcp->mc_spare, 0, sizeof(mcp->mc_spare));

    return 0;
}

/*
 * Compare to arm/arm/exec_machdep.c sendsig()
 * Assumes that the memory is locked if frame points to user memory.
 */
abi_long setup_sigframe_arch(CPUARMState *env, abi_ulong frame_addr,
                             struct target_sigframe *frame, int flags)
{
    target_mcontext_t *mcp = &frame->sf_uc.uc_mcontext;

    get_mcontext(env, mcp, flags);
    get_vfpcontext(env, frame_addr, frame);
    return 0;
}

/* Compare to arm/arm/exec_machdep.c set_mcontext() */
abi_long set_mcontext(CPUARMState *env, target_mcontext_t *mcp, int srflag)
{
    int err = 0;
    const uint32_t *gr = mcp->__gregs;
    uint32_t cpsr, ccpsr = cpsr_read(env);
    uint32_t fpscr, mask;

    cpsr = tswap32(gr[TARGET_REG_CPSR]);
    /*
     * Only allow certain bits to change, reject attempted changes to non-user
     * bits. In addition, make sure we're headed for user mode and none of the
     * interrupt bits are set.
     */
    if ((ccpsr & ~CPSR_USER) != (cpsr & ~CPSR_USER)) {
        return -TARGET_EINVAL;
    }
    if ((cpsr & CPSR_M) != ARM_CPU_MODE_USR ||
        (cpsr & (CPSR_I | CPSR_F)) != 0) {
        return -TARGET_EINVAL;
    }

    /*
     * The movs pc,lr instruction that implements the return to userland masks
     * these bits out.
     */
    mask = cpsr & CPSR_T ? 0x1 : 0x3;

    /*
     * Make sure that we either have no vfp, or it's the correct size.
     * FreeBSD just ignores it, though, so maybe we'll need to adjust
     * things below instead.
     */
    if (mcp->mc_vfp_size != 0 && mcp->mc_vfp_size != sizeof(target_mcontext_vfp_t)) {
        return -TARGET_EINVAL;
    }

    env->regs[0] = tswap32(gr[TARGET_REG_R0]);
    env->regs[1] = tswap32(gr[TARGET_REG_R1]);
    env->regs[2] = tswap32(gr[TARGET_REG_R2]);
    env->regs[3] = tswap32(gr[TARGET_REG_R3]);
    env->regs[4] = tswap32(gr[TARGET_REG_R4]);
    env->regs[5] = tswap32(gr[TARGET_REG_R5]);
    env->regs[6] = tswap32(gr[TARGET_REG_R6]);
    env->regs[7] = tswap32(gr[TARGET_REG_R7]);
    env->regs[8] = tswap32(gr[TARGET_REG_R8]);
    env->regs[9] = tswap32(gr[TARGET_REG_R9]);
    env->regs[10] = tswap32(gr[TARGET_REG_R10]);
    env->regs[11] = tswap32(gr[TARGET_REG_R11]);
    env->regs[12] = tswap32(gr[TARGET_REG_R12]);

    env->regs[13] = tswap32(gr[TARGET_REG_SP]);
    env->regs[14] = tswap32(gr[TARGET_REG_LR]);
    env->regs[15] = tswap32(gr[TARGET_REG_PC] & ~mask);
    if (mcp->mc_vfp_size != 0 && mcp->mc_vfp_ptr != 0) {
        /* see set_vfpcontext in sys/arm/arm/exec_machdep.c */
        target_mcontext_vfp_t *vfp;

        vfp = lock_user(VERIFY_READ, mcp->mc_vfp_ptr, sizeof(*vfp), 1);
        for (int i = 0; i < 32; i++) {
            __get_user(*aa32_vfp_dreg(env, i), &vfp->mcv_reg[i]);
        }
        __get_user(fpscr, &vfp->mcv_fpscr);
        vfp_set_fpscr(env, fpscr);
        unlock_user(vfp, mcp->mc_vfp_ptr, sizeof(target_ucontext_t));

        /*
         * linux-user sets fpexc, fpinst and fpinst2, but these aren't in
         * FreeBSD's mcontext, what to do?
         */
    }
    cpsr_write(env, cpsr, CPSR_USER | CPSR_EXEC, CPSRWriteByInstr);

    return err;
}

/* Compare to arm/arm/machdep.c sys_sigreturn() */
abi_long get_ucontext_sigreturn(CPUARMState *env, abi_ulong target_sf,
                                abi_ulong *target_uc)
{
    *target_uc = target_sf;

    return 0;
}