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Re: [PATCH] target/rx: update PC correctly in wait instruction
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From: |
Yoshinori Sato |
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Subject: |
Re: [PATCH] target/rx: update PC correctly in wait instruction |
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Date: |
Mon, 18 Apr 2022 22:18:34 +0900 |
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User-agent: |
Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (Gojō) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) |
On Sun, 17 Apr 2022 15:02:25 +0900,
Tomoaki Kawada wrote:
>
> `cpu_pc` at this point does not necessary point to the current
> instruction (i.e., the wait instruction being translated), so it's
> incorrect to calculate the new value of `cpu_pc` based on this. It must
> be updated with `ctx->base.pc_next`, which contains the correct address
> of the next instruction.
>
> This change fixes the wait instruction skipping the subsequent branch
> when used in an idle loop like this:
>
> 0: wait
> bra.b 0b
> brk // should be unreachable
>
> Signed-off-by: Tomoaki Kawada <i@yvt.jp>
> ---
> target/rx/translate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/rx/translate.c b/target/rx/translate.c
> index 5db8f79a82..f8812e7a6c 100644
> --- a/target/rx/translate.c
> +++ b/target/rx/translate.c
> @@ -2281,7 +2281,7 @@ static bool trans_INT(DisasContext *ctx, arg_INT *a)
> static bool trans_WAIT(DisasContext *ctx, arg_WAIT *a)
> {
> if (is_privileged(ctx, 1)) {
> - tcg_gen_addi_i32(cpu_pc, cpu_pc, 2);
> + tcg_gen_movi_i32(cpu_pc, ctx->base.pc_next);
> gen_helper_wait(cpu_env);
> }
> return true;
> --
> 2.35.1
>
Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>
--
Yosinori Sato