Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4

[Helge Deller]

On 17.01.20 02:53, Richard Henderson wrote:
> The PA-RISC 1.1 specification says that LDCW must be aligned mod 16
> or the operation is undefined.  However, real hardware only generates
> an unaligned access trap for unaligned mod 4.
>
> Match real hardware, but diagnose with GUEST_ERROR a violation of the
> specification.
>
> Reported-by: Helge Deller <address@hidden>
> Suggested-by: John David Anglin <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
>
> Helge, can you please test this against your failing kernel?
> You will of course want to add -D logfile -d guest_errors to
> you qemu command-line.

Yes, works as expected.
Thanks!

Please add:
Tested-by: Helge Deller <address@hidden>


[deller]$ tail -f logfile
Undefined ldc to address unaligned mod 16: 00000504fa6c7848
Undefined ldc to address unaligned mod 16: 00000504fa6c7a48
Undefined ldc to address unaligned mod 16: 00000506f9434848
Undefined ldc to address unaligned mod 16: 00000506f9434a48
Undefined ldc to address unaligned mod 16: 00000508fa036848
Undefined ldc to address unaligned mod 16: 00000508fa036a48
Undefined ldc to address unaligned mod 16: 0000050afa8c4848
Undefined ldc to address unaligned mod 16: 0000050afa8c4a48
Undefined ldc to address unaligned mod 16: 0000050cf94d1848
Undefined ldc to address unaligned mod 16: 0000050cf94d1a48
....



>
>
> r~
>
> ---
>  target/hppa/helper.h    | 2 ++
>  target/hppa/op_helper.c | 9 +++++++++
>  target/hppa/translate.c | 6 +++++-
>  3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/target/hppa/helper.h b/target/hppa/helper.h
> index 38d834ef6b..2d483aab58 100644
> --- a/target/hppa/helper.h
> +++ b/target/hppa/helper.h
> @@ -17,6 +17,8 @@ DEF_HELPER_FLAGS_3(stby_b_parallel, TCG_CALL_NO_WG, void, 
> env, tl, tr)
>  DEF_HELPER_FLAGS_3(stby_e, TCG_CALL_NO_WG, void, env, tl, tr)
>  DEF_HELPER_FLAGS_3(stby_e_parallel, TCG_CALL_NO_WG, void, env, tl, tr)
>
> +DEF_HELPER_FLAGS_1(ldc_check, TCG_CALL_NO_RWG, void, tl)
> +
>  DEF_HELPER_FLAGS_4(probe, TCG_CALL_NO_WG, tr, env, tl, i32, i32)
>
>  DEF_HELPER_FLAGS_1(loaded_fr0, TCG_CALL_NO_RWG, void, env)
> diff --git a/target/hppa/op_helper.c b/target/hppa/op_helper.c
> index f0516e81f1..345cef2c08 100644
> --- a/target/hppa/op_helper.c
> +++ b/target/hppa/op_helper.c
> @@ -153,6 +153,15 @@ void HELPER(stby_e_parallel)(CPUHPPAState *env, 
> target_ulong addr,
>      do_stby_e(env, addr, val, true, GETPC());
>  }
>
> +void HELPER(ldc_check)(target_ulong addr)
> +{
> +    if (unlikely(addr & 0xf)) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "Undefined ldc to address unaligned mod 16: "
> +                      TARGET_FMT_lx "\n", addr);
> +    }
> +}
> +
>  target_ureg HELPER(probe)(CPUHPPAState *env, target_ulong addr,
>                            uint32_t level, uint32_t want)
>  {
> diff --git a/target/hppa/translate.c b/target/hppa/translate.c
> index 2f8d407a82..669381dc1d 100644
> --- a/target/hppa/translate.c
> +++ b/target/hppa/translate.c
> @@ -2942,7 +2942,7 @@ static bool trans_st(DisasContext *ctx, arg_ldst *a)
>
>  static bool trans_ldc(DisasContext *ctx, arg_ldst *a)
>  {
> -    MemOp mop = MO_TEUL | MO_ALIGN_16 | a->size;
> +    MemOp mop = MO_TE | MO_ALIGN | a->size;
>      TCGv_reg zero, dest, ofs;
>      TCGv_tl addr;
>
> @@ -2958,8 +2958,12 @@ static bool trans_ldc(DisasContext *ctx, arg_ldst *a)
>
>      form_gva(ctx, &addr, &ofs, a->b, a->x, a->scale ? a->size : 0,
>               a->disp, a->sp, a->m, ctx->mmu_idx == MMU_PHYS_IDX);
> +
> +    gen_helper_ldc_check(addr);
>      zero = tcg_const_reg(0);
>      tcg_gen_atomic_xchg_reg(dest, addr, zero, ctx->mmu_idx, mop);
> +    tcg_temp_free(zero);
> +
>      if (a->m) {
>          save_gpr(ctx, a->b, ofs);
>      }
>