Re: [PATCH 1/2] gdbstub: Assert len read from each register

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 4/9/20 6:49 PM, Peter Xu wrote:
> This can expose the issue earlier on which register returned the wrong
> result.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>   gdbstub.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/gdbstub.c b/gdbstub.c
> index 171e150950..f763545e81 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -911,17 +911,22 @@ static int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
>       CPUClass *cc = CPU_GET_CLASS(cpu);
>       CPUArchState *env = cpu->env_ptr;
>       GDBRegisterState *r;
> +    int len = 0, orig_len = buf->len;
>   
>       if (reg < cc->gdb_num_core_regs) {
> -        return cc->gdb_read_register(cpu, buf, reg);
> +        len = cc->gdb_read_register(cpu, buf, reg);

This change the code flow. We could add ...:

            goto out;

>       }

... or use else?
>   
>       for (r = cpu->gdb_regs; r; r = r->next) {
>           if (r->base_reg <= reg && reg < r->base_reg + r->num_regs) {
> -            return r->get_reg(env, buf, reg - r->base_reg);
> +            len = r->get_reg(env, buf, reg - r->base_reg);
> +            break;
>           }
>       }
> -    return 0;
> +

   out:

> +    assert(len == buf->len - orig_len);
> +
> +    return len;
>   }
>   
>   static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
>