Re: [PATCH] riscv: Separate FPU register size from core register size in gdbstub

[Alistair Francis]

On Tue, Jan 28, 2020 at 2:40 PM Keith Packard via <address@hidden> wrote:
>
> The size of the FPU registers is dictated by the 'f' and 'd' features,
> not the core processor register size. Processors with the 'd' feature
> have 64-bit FPU registers. Processors without the 'd' feature but with
> the 'f' feature have 32-bit FPU registers.
>
> Signed-off-by: Keith Packard <address@hidden>
> ---
>  configure              |  4 ++--
>  target/riscv/gdbstub.c | 18 +++++++++---------
>  2 files changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/configure b/configure
> index a72a5def57..c21bff8d10 100755
> --- a/configure
> +++ b/configure
> @@ -7709,13 +7709,13 @@ case "$target_name" in
>      TARGET_BASE_ARCH=riscv
>      TARGET_ABI_DIR=riscv
>      mttcg=yes
> -    gdb_xml_files="riscv-32bit-cpu.xml riscv-32bit-fpu.xml 
> riscv-32bit-csr.xml riscv-32bit-virtual.xml"
> +    gdb_xml_files="riscv-32bit-cpu.xml riscv-32bit-fpu.xml 
> riscv-64bit-fpu.xml riscv-32bit-csr.xml riscv-32bit-virtual.xml"
>    ;;
>    riscv64)
>      TARGET_BASE_ARCH=riscv
>      TARGET_ABI_DIR=riscv
>      mttcg=yes
> -    gdb_xml_files="riscv-64bit-cpu.xml riscv-64bit-fpu.xml 
> riscv-64bit-csr.xml riscv-64bit-virtual.xml"
> +    gdb_xml_files="riscv-64bit-cpu.xml riscv-32bit-fpu.xml 
> riscv-64bit-fpu.xml riscv-64bit-csr.xml riscv-64bit-virtual.xml"
>    ;;
>    sh4|sh4eb)
>      TARGET_ARCH=sh4
> diff --git a/target/riscv/gdbstub.c b/target/riscv/gdbstub.c
> index 1a7947e019..c1803a5916 100644
> --- a/target/riscv/gdbstub.c
> +++ b/target/riscv/gdbstub.c
> @@ -303,7 +303,10 @@ int riscv_cpu_gdb_write_register(CPUState *cs, uint8_t 
> *mem_buf, int n)
>  static int riscv_gdb_get_fpu(CPURISCVState *env, uint8_t *mem_buf, int n)
>  {
>      if (n < 32) {
> -        return gdb_get_reg64(mem_buf, env->fpr[n]);
> +        if (env->misa & RVD)
> +            return gdb_get_reg64(mem_buf, env->fpr[n]);
> +        if (env->misa & RVF)
> +            return gdb_get_reg32(mem_buf, env->fpr[n]);

You need brackets around all if statements, besides that:

Reviewed-by: Alistair Francis <address@hidden>

Alistair

>      /* there is hole between ft11 and fflags in fpu.xml */
>      } else if (n < 36 && n > 32) {
>          target_ulong val = 0;
> @@ -403,23 +406,20 @@ void riscv_cpu_register_gdb_regs_for_features(CPUState 
> *cs)
>  {
>      RISCVCPU *cpu = RISCV_CPU(cs);
>      CPURISCVState *env = &cpu->env;
> -#if defined(TARGET_RISCV32)
> -    if (env->misa & RVF) {
> +    if (env->misa & RVD) {
> +        gdb_register_coprocessor(cs, riscv_gdb_get_fpu, riscv_gdb_set_fpu,
> +                                 36, "riscv-64bit-fpu.xml", 0);
> +    } else if (env->misa & RVF) {
>          gdb_register_coprocessor(cs, riscv_gdb_get_fpu, riscv_gdb_set_fpu,
>                                   36, "riscv-32bit-fpu.xml", 0);
>      }
> -
> +#if defined(TARGET_RISCV32)
>      gdb_register_coprocessor(cs, riscv_gdb_get_csr, riscv_gdb_set_csr,
>                               240, "riscv-32bit-csr.xml", 0);
>
>      gdb_register_coprocessor(cs, riscv_gdb_get_virtual, 
> riscv_gdb_set_virtual,
>                               1, "riscv-32bit-virtual.xml", 0);
>  #elif defined(TARGET_RISCV64)
> -    if (env->misa & RVF) {
> -        gdb_register_coprocessor(cs, riscv_gdb_get_fpu, riscv_gdb_set_fpu,
> -                                 36, "riscv-64bit-fpu.xml", 0);
> -    }
> -
>      gdb_register_coprocessor(cs, riscv_gdb_get_csr, riscv_gdb_set_csr,
>                               240, "riscv-64bit-csr.xml", 0);
>
> --
> 2.25.0
>
>