Re: [PATCH v9 68/76] target/riscv: gdb: support vector registers for rv64 & rv32

[Alistair Francis]

On Fri, Oct 29, 2021 at 8:24 PM <frank.chang@sifive.com> wrote:
>
> From: Hsiangkai Wang <kai.wang@sifive.com>
>
> Signed-off-by: Hsiangkai Wang <kai.wang@sifive.com>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Frank Chang <frank.chang@sifive.com>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/cpu.c     |   2 +
>  target/riscv/cpu.h     |   1 +
>  target/riscv/gdbstub.c | 184 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 187 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index c760ea08621..860f356bd99 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -675,6 +675,8 @@ static const char *riscv_gdb_get_dynamic_xml(CPUState 
> *cs, const char *xmlname)
>
>      if (strcmp(xmlname, "riscv-csr.xml") == 0) {
>          return cpu->dyn_csr_xml;
> +    } else if (strcmp(xmlname, "riscv-vector.xml") == 0) {
> +        return cpu->dyn_vreg_xml;
>      }
>
>      return NULL;
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 5d93ccdfa71..dc10f27093b 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -291,6 +291,7 @@ struct RISCVCPU {
>      CPURISCVState env;
>
>      char *dyn_csr_xml;
> +    char *dyn_vreg_xml;
>
>      /* Configuration Settings */
>      struct {
> diff --git a/target/riscv/gdbstub.c b/target/riscv/gdbstub.c
> index 23429179e2e..881ab333924 100644
> --- a/target/riscv/gdbstub.c
> +++ b/target/riscv/gdbstub.c
> @@ -20,6 +20,32 @@
>  #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);
> @@ -101,6 +127,96 @@ static int riscv_gdb_set_fpu(CPURISCVState *env, uint8_t 
> *mem_buf, int n)
>      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) {
> @@ -187,6 +303,68 @@ static int riscv_gen_dynamic_csr_xml(CPUState *cs, int 
> base_reg)
>      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);
> @@ -198,6 +376,12 @@ void riscv_cpu_register_gdb_regs_for_features(CPUState 
> *cs)
>          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);
> +    }
>  #if defined(TARGET_RISCV32)
>      gdb_register_coprocessor(cs, riscv_gdb_get_virtual, 
> riscv_gdb_set_virtual,
>                               1, "riscv-32bit-virtual.xml", 0);
> --
> 2.25.1
>
>