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qemu/target/riscv/gdbstub.c
Frédéric Pétrot 6c3a924725 target/riscv: correct "code should not be reached" for x-rv128 
The addition of uxl support in gdbstub adds a few checks on the maximum
register length, but omitted MXL_RV128, an experimental feature.
This patch makes rv128 react as rv64, as previously.

Signed-off-by: Frédéric Pétrot <frederic.petrot@univ-grenoble-alpes.fr>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220124202456.420258-1-frederic.petrot@univ-grenoble-alpes.fr
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2022-02-16 12:24:18 +10:00

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/*
* RISC-V GDB Server Stub
*
* Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2 or later, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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 "exec/gdbstub.h"
#include "cpu.h"
struct TypeSize {
const char *gdb_type;
const char *id;
int size;
const char suffix;
};
static const struct TypeSize vec_lanes[] = {
/* quads */
{ "uint128", "quads", 128, 'q' },
/* 64 bit */
{ "uint64", "longs", 64, 'l' },
/* 32 bit */
{ "uint32", "words", 32, 'w' },
/* 16 bit */
{ "uint16", "shorts", 16, 's' },
/*
* TODO: currently there is no reliable way of telling
* if the remote gdb actually understands ieee_half so
* we don't expose it in the target description for now.
* { "ieee_half", 16, 'h', 'f' },
*/
/* bytes */
{ "uint8", "bytes", 8, 'b' },
};
int riscv_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
{
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
target_ulong tmp;
if (n < 32) {
tmp = env->gpr[n];
} else if (n == 32) {
tmp = env->pc;
} else {
return 0;
}
switch (env->misa_mxl_max) {
case MXL_RV32:
return gdb_get_reg32(mem_buf, tmp);
case MXL_RV64:
case MXL_RV128:
return gdb_get_reg64(mem_buf, tmp);
default:
g_assert_not_reached();
}
return 0;
}
int riscv_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
{
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
int length = 0;
target_ulong tmp;
switch (env->misa_mxl_max) {
case MXL_RV32:
tmp = (int32_t)ldl_p(mem_buf);
length = 4;
break;
case MXL_RV64:
case MXL_RV128:
if (env->xl < MXL_RV64) {
tmp = (int32_t)ldq_p(mem_buf);
} else {
tmp = ldq_p(mem_buf);
}
length = 8;
break;
default:
g_assert_not_reached();
}
if (n > 0 && n < 32) {
env->gpr[n] = tmp;
} else if (n == 32) {
env->pc = tmp;
}
return length;
}
static int riscv_gdb_get_fpu(CPURISCVState *env, GByteArray *buf, int n)
{
if (n < 32) {
if (env->misa_ext & RVD) {
return gdb_get_reg64(buf, env->fpr[n]);
}
if (env->misa_ext & RVF) {
return gdb_get_reg32(buf, env->fpr[n]);
}
/* there is hole between ft11 and fflags in fpu.xml */
} else if (n < 36 && n > 32) {
target_ulong val = 0;
int result;
/*
* CSR_FFLAGS is at index 1 in csr_register, and gdb says it is FP
* register 33, so we recalculate the map index.
* This also works for CSR_FRM and CSR_FCSR.
*/
result = riscv_csrrw_debug(env, n - 32, &val,
0, 0);
if (result == RISCV_EXCP_NONE) {
return gdb_get_regl(buf, val);
}
}
return 0;
}
static int riscv_gdb_set_fpu(CPURISCVState *env, uint8_t *mem_buf, int n)
{
if (n < 32) {
env->fpr[n] = ldq_p(mem_buf); /* always 64-bit */
return sizeof(uint64_t);
/* there is hole between ft11 and fflags in fpu.xml */
} else if (n < 36 && n > 32) {
target_ulong val = ldtul_p(mem_buf);
int result;
/*
* CSR_FFLAGS is at index 1 in csr_register, and gdb says it is FP
* register 33, so we recalculate the map index.
* This also works for CSR_FRM and CSR_FCSR.
*/
result = riscv_csrrw_debug(env, n - 32, NULL,
val, -1);
if (result == RISCV_EXCP_NONE) {
return sizeof(target_ulong);
}
}
return 0;
}
/*
* Convert register index number passed by GDB to the correspond
* vector CSR number. Vector CSRs are defined after vector registers
* in dynamic generated riscv-vector.xml, thus the starting register index
* of vector CSRs is 32.
* Return 0 if register index number is out of range.
*/
static int riscv_gdb_vector_csrno(int num_regs)
{
/*
* The order of vector CSRs in the switch case
* should match with the order defined in csr_ops[].
*/
switch (num_regs) {
case 32:
return CSR_VSTART;
case 33:
return CSR_VXSAT;
case 34:
return CSR_VXRM;
case 35:
return CSR_VCSR;
case 36:
return CSR_VL;
case 37:
return CSR_VTYPE;
case 38:
return CSR_VLENB;
default:
/* Unknown register. */
return 0;
}
}
static int riscv_gdb_get_vector(CPURISCVState *env, GByteArray *buf, int n)
{
uint16_t vlenb = env_archcpu(env)->cfg.vlen >> 3;
if (n < 32) {
int i;
int cnt = 0;
for (i = 0; i < vlenb; i += 8) {
cnt += gdb_get_reg64(buf,
env->vreg[(n * vlenb + i) / 8]);
}
return cnt;
}
int csrno = riscv_gdb_vector_csrno(n);
if (!csrno) {
return 0;
}
target_ulong val = 0;
int result = riscv_csrrw_debug(env, csrno, &val, 0, 0);
if (result == 0) {
return gdb_get_regl(buf, val);
}
return 0;
}
static int riscv_gdb_set_vector(CPURISCVState *env, uint8_t *mem_buf, int n)
{
uint16_t vlenb = env_archcpu(env)->cfg.vlen >> 3;
if (n < 32) {
int i;
for (i = 0; i < vlenb; i += 8) {
env->vreg[(n * vlenb + i) / 8] = ldq_p(mem_buf + i);
}
return vlenb;
}
int csrno = riscv_gdb_vector_csrno(n);
if (!csrno) {
return 0;
}
target_ulong val = ldtul_p(mem_buf);
int result = riscv_csrrw_debug(env, csrno, NULL, val, -1);
if (result == 0) {
return sizeof(target_ulong);
}
return 0;
}
static int riscv_gdb_get_csr(CPURISCVState *env, GByteArray *buf, int n)
{
if (n < CSR_TABLE_SIZE) {
target_ulong val = 0;
int result;
result = riscv_csrrw_debug(env, n, &val, 0, 0);
if (result == RISCV_EXCP_NONE) {
return gdb_get_regl(buf, val);
}
}
return 0;
}
static int riscv_gdb_set_csr(CPURISCVState *env, uint8_t *mem_buf, int n)
{
if (n < CSR_TABLE_SIZE) {
target_ulong val = ldtul_p(mem_buf);
int result;
result = riscv_csrrw_debug(env, n, NULL, val, -1);
if (result == RISCV_EXCP_NONE) {
return sizeof(target_ulong);
}
}
return 0;
}
static int riscv_gdb_get_virtual(CPURISCVState *cs, GByteArray *buf, int n)
{
if (n == 0) {
#ifdef CONFIG_USER_ONLY
return gdb_get_regl(buf, 0);
#else
return gdb_get_regl(buf, cs->priv);
#endif
}
return 0;
}
static int riscv_gdb_set_virtual(CPURISCVState *cs, uint8_t *mem_buf, int n)
{
if (n == 0) {
#ifndef CONFIG_USER_ONLY
cs->priv = ldtul_p(mem_buf) & 0x3;
if (cs->priv == PRV_H) {
cs->priv = PRV_S;
}
#endif
return sizeof(target_ulong);
}
return 0;
}
static int riscv_gen_dynamic_csr_xml(CPUState *cs, int base_reg)
{
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
GString *s = g_string_new(NULL);
riscv_csr_predicate_fn predicate;
int bitsize = 16 << env->misa_mxl_max;
int i;
/* Until gdb knows about 128-bit registers */
if (bitsize > 64) {
bitsize = 64;
}
g_string_printf(s, "<?xml version=\"1.0\"?>");
g_string_append_printf(s, "<!DOCTYPE feature SYSTEM \"gdb-target.dtd\">");
g_string_append_printf(s, "<feature name=\"org.gnu.gdb.riscv.csr\">");
for (i = 0; i < CSR_TABLE_SIZE; i++) {
predicate = csr_ops[i].predicate;
if (predicate && (predicate(env, i) == RISCV_EXCP_NONE)) {
if (csr_ops[i].name) {
g_string_append_printf(s, "<reg name=\"%s\"", csr_ops[i].name);
} else {
g_string_append_printf(s, "<reg name=\"csr%03x\"", i);
}
g_string_append_printf(s, " bitsize=\"%d\"", bitsize);
g_string_append_printf(s, " regnum=\"%d\"/>", base_reg + i);
}
}
g_string_append_printf(s, "</feature>");
cpu->dyn_csr_xml = g_string_free(s, false);
return CSR_TABLE_SIZE;
}
static int ricsv_gen_dynamic_vector_xml(CPUState *cs, int base_reg)
{
RISCVCPU *cpu = RISCV_CPU(cs);
GString *s = g_string_new(NULL);
g_autoptr(GString) ts = g_string_new("");
int reg_width = cpu->cfg.vlen;
int num_regs = 0;
int i;
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.gnu.gdb.riscv.vector\">");
/* First define types and totals in a whole VL */
for (i = 0; i < ARRAY_SIZE(vec_lanes); i++) {
int count = reg_width / vec_lanes[i].size;
g_string_printf(ts, "%s", vec_lanes[i].id);
g_string_append_printf(s,
"<vector id=\"%s\" type=\"%s\" count=\"%d\"/>",
ts->str, vec_lanes[i].gdb_type, count);
}
/* Define unions */
g_string_append_printf(s, "<union id=\"riscv_vector\">");
for (i = 0; i < ARRAY_SIZE(vec_lanes); i++) {
g_string_append_printf(s, "<field name=\"%c\" type=\"%s\"/>",
vec_lanes[i].suffix,
vec_lanes[i].id);
}
g_string_append(s, "</union>");
/* Define vector registers */
for (i = 0; i < 32; i++) {
g_string_append_printf(s,
"<reg name=\"v%d\" bitsize=\"%d\""
" regnum=\"%d\" group=\"vector\""
" type=\"riscv_vector\"/>",
i, reg_width, base_reg++);
num_regs++;
}
/* Define vector CSRs */
const char *vector_csrs[7] = {
"vstart", "vxsat", "vxrm", "vcsr",
"vl", "vtype", "vlenb"
};
for (i = 0; i < 7; i++) {
g_string_append_printf(s,
"<reg name=\"%s\" bitsize=\"%d\""
" regnum=\"%d\" group=\"vector\""
" type=\"int\"/>",
vector_csrs[i], TARGET_LONG_BITS, base_reg++);
num_regs++;
}
g_string_append_printf(s, "</feature>");
cpu->dyn_vreg_xml = g_string_free(s, false);
return num_regs;
}
void riscv_cpu_register_gdb_regs_for_features(CPUState *cs)
{
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
if (env->misa_ext & RVD) {
gdb_register_coprocessor(cs, riscv_gdb_get_fpu, riscv_gdb_set_fpu,
36, "riscv-64bit-fpu.xml", 0);
} else if (env->misa_ext & RVF) {
gdb_register_coprocessor(cs, riscv_gdb_get_fpu, riscv_gdb_set_fpu,
36, "riscv-32bit-fpu.xml", 0);
}
if (env->misa_ext & RVV) {
gdb_register_coprocessor(cs, riscv_gdb_get_vector, riscv_gdb_set_vector,
ricsv_gen_dynamic_vector_xml(cs,
cs->gdb_num_regs),
"riscv-vector.xml", 0);
}
switch (env->misa_mxl_max) {
case MXL_RV32:
gdb_register_coprocessor(cs, riscv_gdb_get_virtual,
riscv_gdb_set_virtual,
1, "riscv-32bit-virtual.xml", 0);
break;
case MXL_RV64:
case MXL_RV128:
gdb_register_coprocessor(cs, riscv_gdb_get_virtual,
riscv_gdb_set_virtual,
1, "riscv-64bit-virtual.xml", 0);
break;
default:
g_assert_not_reached();
}
gdb_register_coprocessor(cs, riscv_gdb_get_csr, riscv_gdb_set_csr,
riscv_gen_dynamic_csr_xml(cs, cs->gdb_num_regs),
"riscv-csr.xml", 0);
}
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