Re: [PATCH 7/9] disas/riscv: Provide infrastructure for vendor extensions

[Alistair Francis]

On Tue, May 30, 2023 at 11:21 PM Christoph Muellner
<christoph.muellner@vrull.eu> wrote:
>
> From: Christoph Müllner <christoph.muellner@vrull.eu>
>
> A previous patch provides a pointer to the RISCVCPUConfig data.
> Let's use this to add the necessary code for vendor extensions.
> This patch does not change the current behaviour, but clearly
> defines how vendor extension support can be added to the disassembler.
>
> Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>

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

Alistair

> ---
>  disas/riscv.c | 34 ++++++++++++++++++++++++++++++----
>  1 file changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/disas/riscv.c b/disas/riscv.c
> index 086edee6a2..db98e3ea6a 100644
> --- a/disas/riscv.c
> +++ b/disas/riscv.c
> @@ -20,6 +20,7 @@
>  #include "qemu/osdep.h"
>  #include "disas/dis-asm.h"
>  #include "disas/riscv.h"
> +#include "target/riscv/cpu-config.h"
>
>  typedef enum {
>      /* 0 is reserved for rv_op_illegal. */
> @@ -4599,13 +4600,38 @@ static void decode_inst_decompress(rv_decode *dec, 
> rv_isa isa)
>  /* disassemble instruction */
>
>  static void
> -disasm_inst(char *buf, size_t buflen, rv_isa isa, uint64_t pc, rv_inst inst)
> +disasm_inst(char *buf, size_t buflen, rv_isa isa, uint64_t pc, rv_inst inst,
> +            struct disassemble_info *info)
>  {
> +    RISCVCPUConfig *cfg = info->private_data;
>      rv_decode dec = { 0 };
>      dec.pc = pc;
>      dec.inst = inst;
> -    dec.opcode_data = rvi_opcode_data;
> -    decode_inst_opcode(&dec, isa);
> +
> +    static const struct {
> +        bool (*guard_func)(const RISCVCPUConfig *);
> +        const rv_opcode_data *opcode_data;
> +        void (*decode_func)(rv_decode *, rv_isa);
> +    } decoders[] = {
> +        { always_true_p, rvi_opcode_data, decode_inst_opcode },
> +    };
> +
> +    for (size_t i = 0; i < ARRAY_SIZE(decoders); i++) {
> +        bool (*guard_func)(const RISCVCPUConfig *) = decoders[i].guard_func;
> +        const rv_opcode_data *opcode_data = decoders[i].opcode_data;
> +        void (*decode_func)(rv_decode *, rv_isa) = decoders[i].decode_func;
> +
> +        if (guard_func(cfg)) {
> +            dec.opcode_data = opcode_data;
> +            decode_func(&dec, isa);
> +            if (dec.op != rv_op_illegal)
> +                break;
> +        }
> +    }
> +
> +    if (dec.op == rv_op_illegal)
> +        dec.opcode_data = rvi_opcode_data;
> +
>      decode_inst_operands(&dec, isa);
>      decode_inst_decompress(&dec, isa);
>      decode_inst_lift_pseudo(&dec);
> @@ -4659,7 +4685,7 @@ print_insn_riscv(bfd_vma memaddr, struct 
> disassemble_info *info, rv_isa isa)
>          break;
>      }
>
> -    disasm_inst(buf, sizeof(buf), isa, memaddr, inst);
> +    disasm_inst(buf, sizeof(buf), isa, memaddr, inst, info);
>      (*info->fprintf_func)(info->stream, "%s", buf);
>
>      return len;
> --
> 2.40.1
>
>