Re: [PATCH v6 3/9] target/ppc: Fix gen_sc to use correct nip

[Nicholas Piggin]

On Thu Feb 22, 2024 at 9:33 PM AEST, BALATON Zoltan wrote:
> Most exceptions are raised with nip pointing to the faulting
> instruction but the sc instruction generating a syscall exception
> leaves nip pointing to next instruction. Fix gen_sc to not use
> gen_exception_err() which sets nip back but correctly set nip to
> pc_next so we don't have to patch this in the exception handlers.
>
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

Mixed feelings about this one still but I suppose I will add it
now you have the tracing corrected. Although one more thing:

> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index 049f636927..6a43eda3b9 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -4535,15 +4535,17 @@ static void gen_hrfid(DisasContext *ctx)
>  #endif
>  static void gen_sc(DisasContext *ctx)
>  {
> -    uint32_t lev;
> -
>      /*
>       * LEV is a 7-bit field, but the top 6 bits are treated as a reserved
>       * field (i.e., ignored). ISA v3.1 changes that to 5 bits, but that is
>       * for Ultravisor which TCG does not support, so just ignore the top 6.
>       */
> -    lev = (ctx->opcode >> 5) & 0x1;
> -    gen_exception_err(ctx, POWERPC_SYSCALL, lev);
> +    uint32_t lev = (ctx->opcode >> 5) & 0x1;
> +
> +    gen_update_nip(ctx, ctx->base.pc_next);
> +    gen_helper_raise_exception_err(tcg_env, 
> tcg_constant_i32(POWERPC_SYSCALL),
> +                                   tcg_constant_i32(lev));
> +    ctx->base.is_jmp = DISAS_NORETURN;
>  }
>  
>  #if defined(TARGET_PPC64)

Can you share this code with gen_exception_err, by making
gen_exception_err_nip that takes the nip?

Thanks,
Nick