Re: [PATCH] target/sparc: Use GET_ASI_CODE for ASI_KERNELTXT and ASI_USERTXT

[M Bazz <bazz@bazz1.com>]

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On Thu, Apr 11, 2024, 10:15 PM Richard Henderson <
richard.henderson@linaro.org> wrote:

> Reads are done with execute access.  It is not clear whether writes
> are legal at all -- for now, leave helper_st_asi unchanged, so that
> we continue to raise an mmu fault.
>
> This generalizes the exiting code for ASI_KERNELTXT to be usable for
> ASI_USERTXT as well, by passing down the MemOpIdx to use.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2281
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2059
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1609
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1166
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/sparc/helper.h      |  3 ++
>  target/sparc/ldst_helper.c | 65 ++++++++++++++++++++++++++------------
>  target/sparc/translate.c   | 49 ++++++++++++++++++++++++++--
>  3 files changed, 95 insertions(+), 22 deletions(-)
>
> diff --git a/target/sparc/helper.h b/target/sparc/helper.h
> index e55fad5b8c..b8087d0d2b 100644
> --- a/target/sparc/helper.h
> +++ b/target/sparc/helper.h
> @@ -32,6 +32,9 @@ DEF_HELPER_FLAGS_3(udiv, TCG_CALL_NO_WG, i64, env, tl,
> tl)
>  DEF_HELPER_FLAGS_3(sdiv, TCG_CALL_NO_WG, i64, env, tl, tl)
>  DEF_HELPER_3(taddcctv, tl, env, tl, tl)
>  DEF_HELPER_3(tsubcctv, tl, env, tl, tl)
> +#if !defined(CONFIG_USER_ONLY) && !defined(TARGET_SPARC64)
> +DEF_HELPER_FLAGS_3(ld_code, TCG_CALL_NO_WG, i64, env, tl, i32)
> +#endif
>  #if !defined(CONFIG_USER_ONLY) || defined(TARGET_SPARC64)
>  DEF_HELPER_FLAGS_4(ld_asi, TCG_CALL_NO_WG, i64, env, tl, int, i32)
>  DEF_HELPER_FLAGS_5(st_asi, TCG_CALL_NO_WG, void, env, tl, i64, int, i32)
> diff --git a/target/sparc/ldst_helper.c b/target/sparc/ldst_helper.c
> index e581bb42ac..2846a86cc4 100644
> --- a/target/sparc/ldst_helper.c
> +++ b/target/sparc/ldst_helper.c
> @@ -585,7 +585,6 @@ uint64_t helper_ld_asi(CPUSPARCState *env,
> target_ulong addr,
>  #if defined(DEBUG_MXCC) || defined(DEBUG_ASI)
>      uint32_t last_addr = addr;
>  #endif
> -    MemOpIdx oi;
>
>      do_check_align(env, addr, size - 1, GETPC());
>      switch (asi) {
> @@ -684,24 +683,6 @@ uint64_t helper_ld_asi(CPUSPARCState *env,
> target_ulong addr,
>      case ASI_M_DIAGS:   /* Turbosparc DTLB Diagnostic */
>      case ASI_M_IODIAG:  /* Turbosparc IOTLB Diagnostic */
>          break;
> -    case ASI_KERNELTXT: /* Supervisor code access */
> -        oi = make_memop_idx(memop, cpu_mmu_index(env_cpu(env), true));
> -        switch (size) {
> -        case 1:
> -            ret = cpu_ldb_code_mmu(env, addr, oi, GETPC());
> -            break;
> -        case 2:
> -            ret = cpu_ldw_code_mmu(env, addr, oi, GETPC());
> -            break;
> -        default:
> -        case 4:
> -            ret = cpu_ldl_code_mmu(env, addr, oi, GETPC());
> -            break;
> -        case 8:
> -            ret = cpu_ldq_code_mmu(env, addr, oi, GETPC());
> -            break;
> -        }
> -        break;
>      case ASI_M_TXTC_TAG:   /* SparcStation 5 I-cache tag */
>      case ASI_M_TXTC_DATA:  /* SparcStation 5 I-cache data */
>      case ASI_M_DATAC_TAG:  /* SparcStation 5 D-cache tag */
> @@ -779,7 +760,6 @@ uint64_t helper_ld_asi(CPUSPARCState *env,
> target_ulong addr,
>      case 0x4c: /* SuperSPARC MMU Breakpoint Action */
>          ret = env->mmubpaction;
>          break;
> -    case ASI_USERTXT: /* User code access, XXX */
>      default:
>          sparc_raise_mmu_fault(cs, addr, false, false, asi, size, GETPC());
>          ret = 0;
> @@ -787,6 +767,8 @@ uint64_t helper_ld_asi(CPUSPARCState *env,
> target_ulong addr,
>
>      case ASI_USERDATA: /* User data access */
>      case ASI_KERNELDATA: /* Supervisor data access */
> +    case ASI_USERTXT: /* User code access */
> +    case ASI_KERNELTXT: /* Supervisor code access */
>      case ASI_P: /* Implicit primary context data access (v9 only?) */
>      case ASI_M_BYPASS:    /* MMU passthrough */
>      case ASI_LEON_BYPASS: /* LEON MMU passthrough */
> @@ -1161,6 +1143,49 @@ void helper_st_asi(CPUSPARCState *env, target_ulong
> addr, uint64_t val,
>  #endif
>  }
>
> +uint64_t helper_ld_code(CPUSPARCState *env, target_ulong addr, uint32_t
> oi)
> +{
> +    MemOp mop = get_memop(oi);
> +    uintptr_t ra = GETPC();
> +    uint64_t ret;
> +
> +    switch (mop & MO_SIZE) {
> +    case MO_8:
> +        ret = cpu_ldb_code_mmu(env, addr, oi, ra);
> +        if (mop & MO_SIGN) {
> +            ret = (int8_t)ret;
> +        }
> +        break;
> +    case MO_16:
> +        ret = cpu_ldw_code_mmu(env, addr, oi, ra);
> +        if ((mop & MO_BSWAP) != MO_TE) {
> +            ret = bswap16(ret);
> +        }
> +        if (mop & MO_SIGN) {
> +            ret = (int16_t)ret;
> +        }
> +        break;
> +    case MO_32:
> +        ret = cpu_ldl_code_mmu(env, addr, oi, ra);
> +        if ((mop & MO_BSWAP) != MO_TE) {
> +            ret = bswap32(ret);
> +        }
> +        if (mop & MO_SIGN) {
> +            ret = (int32_t)ret;
> +        }
> +        break;
> +    case MO_64:
> +        ret = cpu_ldq_code_mmu(env, addr, oi, ra);
> +        if ((mop & MO_BSWAP) != MO_TE) {
> +            ret = bswap64(ret);
> +        }
> +        break;
> +    default:
> +        g_assert_not_reached();
> +    }
> +    return ret;
> +}
> +
>  #endif /* CONFIG_USER_ONLY */
>  #else /* TARGET_SPARC64 */
>
> diff --git a/target/sparc/translate.c b/target/sparc/translate.c
> index 319934d9bd..c9b9b047df 100644
> --- a/target/sparc/translate.c
> +++ b/target/sparc/translate.c
> @@ -1117,6 +1117,7 @@ typedef enum {
>      GET_ASI_EXCP,
>      GET_ASI_DIRECT,
>      GET_ASI_DTWINX,
> +    GET_ASI_CODE,
>      GET_ASI_BLOCK,
>      GET_ASI_SHORT,
>      GET_ASI_BCOPY,
> @@ -1159,14 +1160,22 @@ static DisasASI resolve_asi(DisasContext *dc, int
> asi, MemOp memop)
>                 || (asi == ASI_USERDATA
>                     && (dc->def->features & CPU_FEATURE_CASA))) {
>          switch (asi) {
> -        case ASI_USERDATA:   /* User data access */
> +        case ASI_USERDATA:    /* User data access */
>              mem_idx = MMU_USER_IDX;
>              type = GET_ASI_DIRECT;
>              break;
> -        case ASI_KERNELDATA: /* Supervisor data access */
> +        case ASI_KERNELDATA:  /* Supervisor data access */
>              mem_idx = MMU_KERNEL_IDX;
>              type = GET_ASI_DIRECT;
>              break;
> +        case ASI_USERTXT:     /* User text access */
> +            mem_idx = MMU_USER_IDX;
> +            type = GET_ASI_CODE;
> +            break;
> +        case ASI_KERNELTXT:   /* Supervisor text access */
> +            mem_idx = MMU_KERNEL_IDX;
> +            type = GET_ASI_CODE;
> +            break;
>          case ASI_M_BYPASS:    /* MMU passthrough */
>          case ASI_LEON_BYPASS: /* LEON MMU passthrough */
>              mem_idx = MMU_PHYS_IDX;
> @@ -1379,6 +1388,22 @@ static void gen_ld_asi(DisasContext *dc, DisasASI
> *da, TCGv dst, TCGv addr)
>      case GET_ASI_DIRECT:
>          tcg_gen_qemu_ld_tl(dst, addr, da->mem_idx, da->memop | MO_ALIGN);
>          break;
> +
> +    case GET_ASI_CODE:
> +#if !defined(CONFIG_USER_ONLY) && !defined(TARGET_SPARC64)
> +        {
> +            MemOpIdx oi = make_memop_idx(da->memop, da->mem_idx);
> +            TCGv_i32 r_oi = tcg_constant_i32(oi);
> +            TCGv_i64 t64 = tcg_temp_new_i64();
> +
> +            gen_helper_ld_code(t64, tcg_env, addr, r_oi);
> +            tcg_gen_trunc_i64_tl(dst, t64);
> +        }
> +        break;
> +#else
> +        g_assert_not_reached();
> +#endif
> +
>      default:
>          {
>              TCGv_i32 r_asi = tcg_constant_i32(da->asi);
> @@ -1791,6 +1816,26 @@ static void gen_ldda_asi(DisasContext *dc, DisasASI
> *da, TCGv addr, int rd)
>          }
>          break;
>
> +    case GET_ASI_CODE:
> +#if !defined(CONFIG_USER_ONLY) && !defined(TARGET_SPARC64)
> +        {
> +            TCGv_i64 tmp = tcg_temp_new_i64();
> +            MemOpIdx oi = make_memop_idx(da->memop, da->mem_idx);
> +
> +            gen_helper_ld_code(tmp, tcg_env, addr, tcg_constant_i32(oi));
> +
> +            /* See above.  */
> +            if ((da->memop & MO_BSWAP) == MO_TE) {
> +                tcg_gen_extr_i64_tl(lo, hi, tmp);
> +            } else {
> +                tcg_gen_extr_i64_tl(hi, lo, tmp);
> +            }
> +        }
> +        break;
> +#else
> +        g_assert_not_reached();
> +#endif
> +
>      default:
>          /* ??? In theory we've handled all of the ASIs that are valid
>             for ldda, and this should raise DAE_invalid_asi.  However,
> --
> 2.34.1
>

Hi Richard,

I see this is in your hands now. I agree with your take on leaving writes
alone. I'm also grateful for the opportunity to collaborate with you.

It brings a smile for the community members who will be touched by this
amazing contribution. I see them happily realizing that this perplexing bug
has been solved, and in our case finally able to use the debuggers we love!
:D

Thanks for the proper fix, qemu sensei!

-bazz

>

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