linux-user/aarch64/target_prctl.h

/*
 * AArch64 specific prctl functions for linux-user
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */
#ifndef AARCH64_TARGET_PRCTL_H
#define AARCH64_TARGET_PRCTL_H

#include "qemu/units.h"
#include "target/arm/cpu-features.h"
#include "mte_user_helper.h"
#include "gcs-internal.h"

static abi_long do_prctl_sve_get_vl(CPUArchState *env)
{
    ARMCPU *cpu = env_archcpu(env);
    if (cpu_isar_feature(aa64_sve, cpu)) {
        /* PSTATE.SM is always unset on syscall entry. */
        return sve_vq(env) * 16;
    }
    return -TARGET_EINVAL;
}
#define do_prctl_sve_get_vl do_prctl_sve_get_vl

static abi_long do_prctl_sve_set_vl(CPUArchState *env, abi_long arg2)
{
    /*
     * We cannot support either PR_SVE_SET_VL_ONEXEC or PR_SVE_VL_INHERIT.
     * Note the kernel definition of sve_vl_valid allows for VQ=512,
     * i.e. VL=8192, even though the current architectural maximum is VQ=16.
     */
    if (cpu_isar_feature(aa64_sve, env_archcpu(env))
        && arg2 >= 0 && arg2 <= 512 * 16 && !(arg2 & 15)) {
        uint32_t vq, old_vq;

        /* PSTATE.SM is always unset on syscall entry. */
        old_vq = sve_vq(env);

        /*
         * Bound the value of arg2, so that we know that it fits into
         * the 4-bit field in ZCR_EL1.  Rely on the hflags rebuild to
         * sort out the length supported by the cpu.
         */
        vq = MAX(arg2 / 16, 1);
        vq = MIN(vq, ARM_MAX_VQ);
        env->vfp.zcr_el[1] = vq - 1;
        arm_rebuild_hflags(env);

        vq = sve_vq(env);
        if (vq < old_vq) {
            aarch64_sve_narrow_vq(env, vq);
        }
        return vq * 16;
    }
    return -TARGET_EINVAL;
}
#define do_prctl_sve_set_vl do_prctl_sve_set_vl

static abi_long do_prctl_sme_get_vl(CPUArchState *env)
{
    ARMCPU *cpu = env_archcpu(env);
    if (cpu_isar_feature(aa64_sme, cpu)) {
        return sme_vq(env) * 16;
    }
    return -TARGET_EINVAL;
}
#define do_prctl_sme_get_vl do_prctl_sme_get_vl

static abi_long do_prctl_sme_set_vl(CPUArchState *env, abi_long arg2)
{
    /*
     * We cannot support either PR_SME_SET_VL_ONEXEC or PR_SME_VL_INHERIT.
     * Note the kernel definition of sve_vl_valid allows for VQ=512,
     * i.e. VL=8192, even though the architectural maximum is VQ=16.
     */
    if (cpu_isar_feature(aa64_sme, env_archcpu(env))
        && arg2 >= 0 && arg2 <= 512 * 16 && !(arg2 & 15)) {
        int vq, old_vq;

        old_vq = sme_vq(env);

        /*
         * Bound the value of vq, so that we know that it fits into
         * the 4-bit field in SMCR_EL1.  Because PSTATE.SM is cleared
         * on syscall entry, we are not modifying the current SVE
         * vector length.
         */
        vq = MAX(arg2 / 16, 1);
        vq = MIN(vq, 16);
        env->vfp.smcr_el[1] =
            FIELD_DP64(env->vfp.smcr_el[1], SMCR, LEN, vq - 1);

        /* Delay rebuilding hflags until we know if ZA must change. */
        vq = sve_vqm1_for_el_sm(env, 0, true) + 1;

        if (vq != old_vq) {
            /*
             * PSTATE.ZA state is cleared on any change to SVL.
             * We need not call arm_rebuild_hflags because PSTATE.SM was
             * cleared on syscall entry, so this hasn't changed VL.
             */
            env->svcr = FIELD_DP64(env->svcr, SVCR, ZA, 0);
            arm_rebuild_hflags(env);
        }
        return vq * 16;
    }
    return -TARGET_EINVAL;
}
#define do_prctl_sme_set_vl do_prctl_sme_set_vl

static abi_long do_prctl_reset_keys(CPUArchState *env, abi_long arg2)
{
    ARMCPU *cpu = env_archcpu(env);

    if (cpu_isar_feature(aa64_pauth, cpu)) {
        int all = (PR_PAC_APIAKEY | PR_PAC_APIBKEY |
                   PR_PAC_APDAKEY | PR_PAC_APDBKEY | PR_PAC_APGAKEY);
        int ret = 0;
        Error *err = NULL;

        if (arg2 == 0) {
            arg2 = all;
        } else if (arg2 & ~all) {
            return -TARGET_EINVAL;
        }
        if (arg2 & PR_PAC_APIAKEY) {
            ret |= qemu_guest_getrandom(&env->keys.apia,
                                        sizeof(ARMPACKey), &err);
        }
        if (arg2 & PR_PAC_APIBKEY) {
            ret |= qemu_guest_getrandom(&env->keys.apib,
                                        sizeof(ARMPACKey), &err);
        }
        if (arg2 & PR_PAC_APDAKEY) {
            ret |= qemu_guest_getrandom(&env->keys.apda,
                                        sizeof(ARMPACKey), &err);
        }
        if (arg2 & PR_PAC_APDBKEY) {
            ret |= qemu_guest_getrandom(&env->keys.apdb,
                                        sizeof(ARMPACKey), &err);
        }
        if (arg2 & PR_PAC_APGAKEY) {
            ret |= qemu_guest_getrandom(&env->keys.apga,
                                        sizeof(ARMPACKey), &err);
        }
        if (ret != 0) {
            /*
             * Some unknown failure in the crypto.  The best
             * we can do is log it and fail the syscall.
             * The real syscall cannot fail this way.
             */
            qemu_log_mask(LOG_UNIMP, "PR_PAC_RESET_KEYS: Crypto failure: %s",
                          error_get_pretty(err));
            error_free(err);
            return -TARGET_EIO;
        }
        return 0;
    }
    return -TARGET_EINVAL;
}
#define do_prctl_reset_keys do_prctl_reset_keys

static abi_long do_prctl_set_tagged_addr_ctrl(CPUArchState *env, abi_long arg2)
{
    abi_ulong valid_mask = PR_TAGGED_ADDR_ENABLE;
    ARMCPU *cpu = env_archcpu(env);

    if (cpu_isar_feature(aa64_mte, cpu)) {
        valid_mask |= PR_MTE_TCF_MASK;
        valid_mask |= PR_MTE_TAG_MASK;
    }

    if (arg2 & ~valid_mask) {
        return -TARGET_EINVAL;
    }
    env->tagged_addr_enable = arg2 & PR_TAGGED_ADDR_ENABLE;

    if (cpu_isar_feature(aa64_mte, cpu)) {
        arm_set_mte_tcf0(env, arg2);

        /*
         * Write PR_MTE_TAG to GCR_EL1[Exclude].
         * Note that the syscall uses an include mask,
         * and hardware uses an exclude mask -- invert.
         */
        env->cp15.gcr_el1 =
            deposit64(env->cp15.gcr_el1, 0, 16, ~arg2 >> PR_MTE_TAG_SHIFT);
        arm_rebuild_hflags(env);
    }
    return 0;
}
#define do_prctl_set_tagged_addr_ctrl do_prctl_set_tagged_addr_ctrl

static abi_long do_prctl_get_tagged_addr_ctrl(CPUArchState *env)
{
    ARMCPU *cpu = env_archcpu(env);
    abi_long ret = 0;

    if (env->tagged_addr_enable) {
        ret |= PR_TAGGED_ADDR_ENABLE;
    }
    if (cpu_isar_feature(aa64_mte, cpu)) {
        /* See do_prctl_set_tagged_addr_ctrl. */
        ret |= extract64(env->cp15.sctlr_el[1], 38, 2) << PR_MTE_TCF_SHIFT;
        ret = deposit64(ret, PR_MTE_TAG_SHIFT, 16, ~env->cp15.gcr_el1);
    }
    return ret;
}
#define do_prctl_get_tagged_addr_ctrl do_prctl_get_tagged_addr_ctrl

static abi_long do_prctl_get_shadow_stack_status(CPUArchState *env,
                                                 abi_long arg2)
{
    ARMCPU *cpu = env_archcpu(env);

    if (!cpu_isar_feature(aa64_gcs, cpu)) {
        return -TARGET_EINVAL;
    }
    return put_user_ual(gcs_get_el0_mode(env), arg2);
}
#define do_prctl_get_shadow_stack_status do_prctl_get_shadow_stack_status

static abi_long gcs_alloc(abi_ulong hint, abi_ulong size)
{
    /*
     * Without softmmu, we cannot protect GCS memory properly.
     * Make do with normal read/write permissions.  This at least allows
     * emulation of correct programs which don't access the gcs stack
     * with normal instructions.
     */
    return target_mmap(hint, size, PROT_READ | PROT_WRITE,
                       MAP_PRIVATE | MAP_ANONYMOUS |
                       (hint ? MAP_FIXED_NOREPLACE : 0), -1, 0);
}

static abi_ulong gcs_new_stack(TaskState *ts)
{
    /* Use guest_stack_size as a proxy for RLIMIT_STACK. */
    abi_ulong size = MIN(MAX(guest_stack_size / 2, TARGET_PAGE_SIZE), 2 * GiB);
    abi_ulong base = gcs_alloc(0, size);

    if (base == -1) {
        return -1;
    }

    ts->gcs_base = base;
    ts->gcs_size = size;
    return base + size - 8;
}

static abi_long do_prctl_set_shadow_stack_status(CPUArchState *env,
                                                 abi_long new_mode)
{
    ARMCPU *cpu = env_archcpu(env);
    TaskState *ts = get_task_state(env_cpu(env));
    abi_long cur_mode;

    if (!cpu_isar_feature(aa64_gcs, cpu)) {
        return -TARGET_EINVAL;
    }
    if (new_mode & ~(PR_SHADOW_STACK_ENABLE |
                     PR_SHADOW_STACK_WRITE |
                     PR_SHADOW_STACK_PUSH)) {
        return -TARGET_EINVAL;
    }

    cur_mode = gcs_get_el0_mode(env);
    if ((new_mode ^ cur_mode) & ts->gcs_el0_locked) {
        return -TARGET_EBUSY;
    }

    if (new_mode & ~cur_mode & PR_SHADOW_STACK_ENABLE) {
        abi_long gcspr;

        if (ts->gcs_base || env->cp15.gcspr_el[0]) {
            return -EINVAL;
        }
        gcspr = gcs_new_stack(ts);
        if (gcspr == -1) {
            return -TARGET_ENOMEM;
        }
        env->cp15.gcspr_el[0] = gcspr;
    }

    gcs_set_el0_mode(env, new_mode);
    arm_rebuild_hflags(env);
    return 0;
}
#define do_prctl_set_shadow_stack_status do_prctl_set_shadow_stack_status

static abi_long do_prctl_lock_shadow_stack_status(CPUArchState *env,
                                                  abi_long arg2)
{
    ARMCPU *cpu = env_archcpu(env);
    TaskState *ts = get_task_state(env_cpu(env));

    if (!cpu_isar_feature(aa64_gcs, cpu)) {
        return -EINVAL;
    }
    ts->gcs_el0_locked |= arg2;
    return 0;
}
#define do_prctl_lock_shadow_stack_status do_prctl_lock_shadow_stack_status

#endif /* AARCH64_TARGET_PRCTL_H */