Re: [Qemu-devel] [PATCH 1/2] tcg: Allow constant pool entries in the prologue

[Laurent Desnogues]

Hello,

On Thu, Oct 26, 2017 at 5:27 PM, Richard Henderson
<address@hidden> wrote:
> Both ARMv6 and AArch64 currently may drop complex guest_base values
> into the constant pool.  But generic code wasn't expecting that, and
> the pool is not emitted.  Correct that.
>
> Reported-by: Laurent Desnogues <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>

Tested-by: Laurent Desnogues <address@hidden>

on an AArch64 host and with running qemu on qemu.

Thanks for taking care of the issue,

Laurent

> ---
>  tcg/tcg.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index 683ff4abb7..c22f1c4441 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -771,12 +771,32 @@ void tcg_prologue_init(TCGContext *s)
>
>      /* Put the prologue at the beginning of code_gen_buffer.  */
>      buf0 = s->code_gen_buffer;
> +    total_size = s->code_gen_buffer_size;
>      s->code_ptr = buf0;
>      s->code_buf = buf0;
> +    s->data_gen_ptr = NULL;
>      s->code_gen_prologue = buf0;
>
> +    /* Compute a high-water mark, at which we voluntarily flush the buffer
> +       and start over.  The size here is arbitrary, significantly larger
> +       than we expect the code generation for any one opcode to require.  */
> +    s->code_gen_highwater = s->code_gen_buffer + (total_size - 
> TCG_HIGHWATER);
> +
> +#ifdef TCG_TARGET_NEED_POOL_LABELS
> +    s->pool_labels = NULL;
> +#endif
> +
>      /* Generate the prologue.  */
>      tcg_target_qemu_prologue(s);
> +
> +#ifdef TCG_TARGET_NEED_POOL_LABELS
> +    /* Allow the prologue to put e.g. guest_base into a pool entry.  */
> +    {
> +        bool ok = tcg_out_pool_finalize(s);
> +        tcg_debug_assert(ok);
> +    }
> +#endif
> +
>      buf1 = s->code_ptr;
>      flush_icache_range((uintptr_t)buf0, (uintptr_t)buf1);
>
> @@ -785,21 +805,36 @@ void tcg_prologue_init(TCGContext *s)
>      s->code_gen_ptr = buf1;
>      s->code_gen_buffer = buf1;
>      s->code_buf = buf1;
> -    total_size = s->code_gen_buffer_size - prologue_size;
> +    total_size -= prologue_size;
>      s->code_gen_buffer_size = total_size;
>
> -    /* Compute a high-water mark, at which we voluntarily flush the buffer
> -       and start over.  The size here is arbitrary, significantly larger
> -       than we expect the code generation for any one opcode to require.  */
> -    s->code_gen_highwater = s->code_gen_buffer + (total_size - 
> TCG_HIGHWATER);
> -
>      tcg_register_jit(s->code_gen_buffer, total_size);
>
>  #ifdef DEBUG_DISAS
>      if (qemu_loglevel_mask(CPU_LOG_TB_OUT_ASM)) {
>          qemu_log_lock();
>          qemu_log("PROLOGUE: [size=%zu]\n", prologue_size);
> -        log_disas(buf0, prologue_size);
> +        if (s->data_gen_ptr) {
> +            size_t code_size = s->data_gen_ptr - buf0;
> +            size_t data_size = prologue_size - code_size;
> +            size_t i;
> +
> +            log_disas(buf0, code_size);
> +
> +            for (i = 0; i < data_size; i += sizeof(tcg_target_ulong)) {
> +                if (sizeof(tcg_target_ulong) == 8) {
> +                    qemu_log("0x%08" PRIxPTR ":  .quad  0x%016" PRIx64 "\n",
> +                             (uintptr_t)s->data_gen_ptr + i,
> +                             *(uint64_t *)(s->data_gen_ptr + i));
> +                } else {
> +                    qemu_log("0x%08" PRIxPTR ":  .long  0x%08x\n",
> +                             (uintptr_t)s->data_gen_ptr + i,
> +                             *(uint32_t *)(s->data_gen_ptr + i));
> +                }
> +            }
> +        } else {
> +            log_disas(buf0, prologue_size);
> +        }
>          qemu_log("\n");
>          qemu_log_flush();
>          qemu_log_unlock();
> --
> 2.13.6
>