qemu/target/arm/gdbstub.c

/*
 * ARM gdb server stub
 *
 * Copyright (c) 2003-2005 Fabrice Bellard
 * Copyright (c) 2013 SUSE LINUX Products GmbH
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
#include "qemu/osdep.h"
#include "cpu.h"
#include "exec/gdbstub.h"
#include "internals.h"
#include "cpregs.h"

typedef struct RegisterSysregXmlParam {
    CPUState *cs;
    GString *s;
    int n;
} RegisterSysregXmlParam;

/* Old gdb always expect FPA registers.  Newer (xml-aware) gdb only expect
   whatever the target description contains.  Due to a historical mishap
   the FPA registers appear in between core integer regs and the CPSR.
   We hack round this by giving the FPA regs zero size when talking to a
   newer gdb.  */

int arm_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
{
    ARMCPU *cpu = ARM_CPU(cs);
    CPUARMState *env = &cpu->env;

    if (n < 16) {
        /* Core integer register.  */
        return gdb_get_reg32(mem_buf, env->regs[n]);
    }
    if (n < 24) {
        /* FPA registers.  */
        if (gdb_has_xml) {
            return 0;
        }
        return gdb_get_zeroes(mem_buf, 12);
    }
    switch (n) {
    case 24:
        /* FPA status register.  */
        if (gdb_has_xml) {
            return 0;
        }
        return gdb_get_reg32(mem_buf, 0);
    case 25:
        /* CPSR, or XPSR for M-profile */
        if (arm_feature(env, ARM_FEATURE_M)) {
            return gdb_get_reg32(mem_buf, xpsr_read(env));
        } else {
            return gdb_get_reg32(mem_buf, cpsr_read(env));
        }
    }
    /* Unknown register.  */
    return 0;
}

int arm_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
{
    ARMCPU *cpu = ARM_CPU(cs);
    CPUARMState *env = &cpu->env;
    uint32_t tmp;

    tmp = ldl_p(mem_buf);

    /*
     * Mask out low bits of PC to workaround gdb bugs.
     * This avoids an assert in thumb_tr_translate_insn, because it is
     * architecturally impossible to misalign the pc.
     * This will probably cause problems if we ever implement the
     * Jazelle DBX extensions.
     */
    if (n == 15) {
        tmp &= ~1;
    }

    if (n < 16) {
        /* Core integer register.  */
        if (n == 13 && arm_feature(env, ARM_FEATURE_M)) {
            /* M profile SP low bits are always 0 */
            tmp &= ~3;
        }
        env->regs[n] = tmp;
        return 4;
    }
    if (n < 24) { /* 16-23 */
        /* FPA registers (ignored).  */
        if (gdb_has_xml) {
            return 0;
        }
        return 12;
    }
    switch (n) {
    case 24:
        /* FPA status register (ignored).  */
        if (gdb_has_xml) {
            return 0;
        }
        return 4;
    case 25:
        /* CPSR, or XPSR for M-profile */
        if (arm_feature(env, ARM_FEATURE_M)) {
            /*
             * Don't allow writing to XPSR.Exception as it can cause
             * a transition into or out of handler mode (it's not
             * writable via the MSR insn so this is a reasonable
             * restriction). Other fields are safe to update.
             */
            xpsr_write(env, tmp, ~XPSR_EXCP);
        } else {
            cpsr_write(env, tmp, 0xffffffff, CPSRWriteByGDBStub);
        }
        return 4;
    }
    /* Unknown register.  */
    return 0;
}

static int vfp_gdb_get_reg(CPUARMState *env, GByteArray *buf, int reg)
{
    ARMCPU *cpu = env_archcpu(env);
    int nregs = cpu_isar_feature(aa32_simd_r32, cpu) ? 32 : 16;

    /* VFP data registers are always little-endian.  */
    if (reg < nregs) {
        return gdb_get_reg64(buf, *aa32_vfp_dreg(env, reg));
    }
    if (arm_feature(env, ARM_FEATURE_NEON)) {
        /* Aliases for Q regs.  */
        nregs += 16;
        if (reg < nregs) {
            uint64_t *q = aa32_vfp_qreg(env, reg - 32);
            return gdb_get_reg128(buf, q[0], q[1]);
        }
    }
    switch (reg - nregs) {
    case 0:
        return gdb_get_reg32(buf, vfp_get_fpscr(env));
    }
    return 0;
}

static int vfp_gdb_set_reg(CPUARMState *env, uint8_t *buf, int reg)
{
    ARMCPU *cpu = env_archcpu(env);
    int nregs = cpu_isar_feature(aa32_simd_r32, cpu) ? 32 : 16;

    if (reg < nregs) {
        *aa32_vfp_dreg(env, reg) = ldq_le_p(buf);
        return 8;
    }
    if (arm_feature(env, ARM_FEATURE_NEON)) {
        nregs += 16;
        if (reg < nregs) {
            uint64_t *q = aa32_vfp_qreg(env, reg - 32);
            q[0] = ldq_le_p(buf);
            q[1] = ldq_le_p(buf + 8);
            return 16;
        }
    }
    switch (reg - nregs) {
    case 0:
        vfp_set_fpscr(env, ldl_p(buf));
        return 4;
    }
    return 0;
}

static int vfp_gdb_get_sysreg(CPUARMState *env, GByteArray *buf, int reg)
{
    switch (reg) {
    case 0:
        return gdb_get_reg32(buf, env->vfp.xregs[ARM_VFP_FPSID]);
    case 1:
        return gdb_get_reg32(buf, env->vfp.xregs[ARM_VFP_FPEXC]);
    }
    return 0;
}

static int vfp_gdb_set_sysreg(CPUARMState *env, uint8_t *buf, int reg)
{
    switch (reg) {
    case 0:
        env->vfp.xregs[ARM_VFP_FPSID] = ldl_p(buf);
        return 4;
    case 1:
        env->vfp.xregs[ARM_VFP_FPEXC] = ldl_p(buf) & (1 << 30);
        return 4;
    }
    return 0;
}

static int mve_gdb_get_reg(CPUARMState *env, GByteArray *buf, int reg)
{
    switch (reg) {
    case 0:
        return gdb_get_reg32(buf, env->v7m.vpr);
    default:
        return 0;
    }
}

static int mve_gdb_set_reg(CPUARMState *env, uint8_t *buf, int reg)
{
    switch (reg) {
    case 0:
        env->v7m.vpr = ldl_p(buf);
        return 4;
    default:
        return 0;
    }
}

/**
 * arm_get/set_gdb_*: get/set a gdb register
 * @env: the CPU state
 * @buf: a buffer to copy to/from
 * @reg: register number (offset from start of group)
 *
 * We return the number of bytes copied
 */

static int arm_gdb_get_sysreg(CPUARMState *env, GByteArray *buf, int reg)
{
    ARMCPU *cpu = env_archcpu(env);
    const ARMCPRegInfo *ri;
    uint32_t key;

    key = cpu->dyn_sysreg_xml.data.cpregs.keys[reg];
    ri = get_arm_cp_reginfo(cpu->cp_regs, key);
    if (ri) {
        if (cpreg_field_is_64bit(ri)) {
            return gdb_get_reg64(buf, (uint64_t)read_raw_cp_reg(env, ri));
        } else {
            return gdb_get_reg32(buf, (uint32_t)read_raw_cp_reg(env, ri));
        }
    }
    return 0;
}

static int arm_gdb_set_sysreg(CPUARMState *env, uint8_t *buf, int reg)
{
    return 0;
}

static void arm_gen_one_xml_sysreg_tag(GString *s, DynamicGDBXMLInfo *dyn_xml,
                                       ARMCPRegInfo *ri, uint32_t ri_key,
                                       int bitsize, int regnum)
{
    g_string_append_printf(s, "<reg name=\"%s\"", ri->name);
    g_string_append_printf(s, " bitsize=\"%d\"", bitsize);
    g_string_append_printf(s, " regnum=\"%d\"", regnum);
    g_string_append_printf(s, " group=\"cp_regs\"/>");
    dyn_xml->data.cpregs.keys[dyn_xml->num] = ri_key;
    dyn_xml->num++;
}

static void arm_register_sysreg_for_xml(gpointer key, gpointer value,
                                        gpointer p)
{
    uint32_t ri_key = (uintptr_t)key;
    ARMCPRegInfo *ri = value;
    RegisterSysregXmlParam *param = (RegisterSysregXmlParam *)p;
    GString *s = param->s;
    ARMCPU *cpu = ARM_CPU(param->cs);
    CPUARMState *env = &cpu->env;
    DynamicGDBXMLInfo *dyn_xml = &cpu->dyn_sysreg_xml;

    if (!(ri->type & (ARM_CP_NO_RAW | ARM_CP_NO_GDB))) {
        if (arm_feature(env, ARM_FEATURE_AARCH64)) {
            if (ri->state == ARM_CP_STATE_AA64) {
                arm_gen_one_xml_sysreg_tag(s , dyn_xml, ri, ri_key, 64,
                                           param->n++);
            }
        } else {
            if (ri->state == ARM_CP_STATE_AA32) {
                if (!arm_feature(env, ARM_FEATURE_EL3) &&
                    (ri->secure & ARM_CP_SECSTATE_S)) {
                    return;
                }
                if (ri->type & ARM_CP_64BIT) {
                    arm_gen_one_xml_sysreg_tag(s , dyn_xml, ri, ri_key, 64,
                                               param->n++);
                } else {
                    arm_gen_one_xml_sysreg_tag(s , dyn_xml, ri, ri_key, 32,
                                               param->n++);
                }
            }
        }
    }
}

static int arm_gen_dynamic_sysreg_xml(CPUState *cs, int base_reg)
{
    ARMCPU *cpu = ARM_CPU(cs);
    GString *s = g_string_new(NULL);
    RegisterSysregXmlParam param = {cs, s, base_reg};

    cpu->dyn_sysreg_xml.num = 0;
    cpu->dyn_sysreg_xml.data.cpregs.keys = g_new(uint32_t, g_hash_table_size(cpu->cp_regs));
    g_string_printf(s, "<?xml version=\"1.0\"?>");
    g_string_append_printf(s, "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">");
    g_string_append_printf(s, "<feature name=\"org.qemu.gdb.arm.sys.regs\">");
    g_hash_table_foreach(cpu->cp_regs, arm_register_sysreg_for_xml, &param);
    g_string_append_printf(s, "</feature>");
    cpu->dyn_sysreg_xml.desc = g_string_free(s, false);
    return cpu->dyn_sysreg_xml.num;
}

const char *arm_gdb_get_dynamic_xml(CPUState *cs, const char *xmlname)
{
    ARMCPU *cpu = ARM_CPU(cs);

    if (strcmp(xmlname, "system-registers.xml") == 0) {
        return cpu->dyn_sysreg_xml.desc;
    } else if (strcmp(xmlname, "sve-registers.xml") == 0) {
        return cpu->dyn_svereg_xml.desc;
    }
    return NULL;
}

void arm_cpu_register_gdb_regs_for_features(ARMCPU *cpu)
{
    CPUState *cs = CPU(cpu);
    CPUARMState *env = &cpu->env;

    if (arm_feature(env, ARM_FEATURE_AARCH64)) {
        /*
         * The lower part of each SVE register aliases to the FPU
         * registers so we don't need to include both.
         */
#ifdef TARGET_AARCH64
        if (isar_feature_aa64_sve(&cpu->isar)) {
            int nreg = arm_gen_dynamic_svereg_xml(cs, cs->gdb_num_regs);
            gdb_register_coprocessor(cs, aarch64_gdb_get_sve_reg,
                                     aarch64_gdb_set_sve_reg, nreg,
                                     "sve-registers.xml", 0);
        } else {
            gdb_register_coprocessor(cs, aarch64_gdb_get_fpu_reg,
                                     aarch64_gdb_set_fpu_reg,
                                     34, "aarch64-fpu.xml", 0);
        }
#endif
    } else {
        if (arm_feature(env, ARM_FEATURE_NEON)) {
            gdb_register_coprocessor(cs, vfp_gdb_get_reg, vfp_gdb_set_reg,
                                     49, "arm-neon.xml", 0);
        } else if (cpu_isar_feature(aa32_simd_r32, cpu)) {
            gdb_register_coprocessor(cs, vfp_gdb_get_reg, vfp_gdb_set_reg,
                                     33, "arm-vfp3.xml", 0);
        } else if (cpu_isar_feature(aa32_vfp_simd, cpu)) {
            gdb_register_coprocessor(cs, vfp_gdb_get_reg, vfp_gdb_set_reg,
                                     17, "arm-vfp.xml", 0);
        }
        if (!arm_feature(env, ARM_FEATURE_M)) {
            /*
             * A and R profile have FP sysregs FPEXC and FPSID that we
             * expose to gdb.
             */
            gdb_register_coprocessor(cs, vfp_gdb_get_sysreg, vfp_gdb_set_sysreg,
                                     2, "arm-vfp-sysregs.xml", 0);
        }
    }
    if (cpu_isar_feature(aa32_mve, cpu)) {
        gdb_register_coprocessor(cs, mve_gdb_get_reg, mve_gdb_set_reg,
                                 1, "arm-m-profile-mve.xml", 0);
    }
    gdb_register_coprocessor(cs, arm_gdb_get_sysreg, arm_gdb_set_sysreg,
                             arm_gen_dynamic_sysreg_xml(cs, cs->gdb_num_regs),
                             "system-registers.xml", 0);

}