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Re: [Qemu-devel] [PATCH v1 2/2] target-microblaze: Rework NOP/zero instr
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-devel] [PATCH v1 2/2] target-microblaze: Rework NOP/zero instruction handling |
Date: |
Thu, 14 Jun 2018 23:44:44 -0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 06/14/2018 05:25 PM, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <address@hidden>
>
> Remove the abort on a sequence of NOP/zero instructions.
> Always return early and avoid decoding NOP/zero instructions.
>
> This fixes Coverity CID 1391443.
>
> Signed-off-by: Edgar E. Iglesias <address@hidden>
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> target/microblaze/translate.c | 15 ++++-----------
> 1 file changed, 4 insertions(+), 11 deletions(-)
>
> diff --git a/target/microblaze/translate.c b/target/microblaze/translate.c
> index 6c64946398..78ca265b04 100644
> --- a/target/microblaze/translate.c
> +++ b/target/microblaze/translate.c
> @@ -90,7 +90,6 @@ typedef struct DisasContext {
> uint32_t jmp_pc;
>
> int abort_at_next_insn;
> - int nr_nops;
> struct TranslationBlock *tb;
> int singlestep_enabled;
> } DisasContext;
> @@ -1576,17 +1575,12 @@ static inline void decode(DisasContext *dc, uint32_t
> ir)
> dc->ir = ir;
> LOG_DIS("%8.8x\t", dc->ir);
>
> - if (dc->ir)
> - dc->nr_nops = 0;
> - else {
> + if (ir == 0) {
> trap_illegal(dc, dc->cpu->env.pvr.regs[2] &
> PVR2_OPCODE_0x0_ILL_MASK);
> -
> - LOG_DIS("nr_nops=%d\t", dc->nr_nops);
> - dc->nr_nops++;
> - if (dc->nr_nops > 4) {
> - cpu_abort(CPU(dc->cpu), "fetching nop sequence\n");
> - }
> + /* Don't decode nop/zero instructions any further. */
> + return;
> }
> +
> /* bit 2 seems to indicate insn type. */
> dc->type_b = ir & (1 << 29);
>
> @@ -1633,7 +1627,6 @@ void gen_intermediate_code(CPUState *cs, struct
> TranslationBlock *tb)
> dc->singlestep_enabled = cs->singlestep_enabled;
> dc->cpustate_changed = 0;
> dc->abort_at_next_insn = 0;
> - dc->nr_nops = 0;
>
> if (pc_start & 3) {
> cpu_abort(cs, "Microblaze: unaligned PC=%x\n", pc_start);
>