From: Alistair Francis <alistair23@gmail.com>
To: Jason Chien <jason.chien@sifive.com>
Cc: qemu-devel@nongnu.org, qemu-riscv@nongnu.org,
"Frank Chang" <frank.chang@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Alistair Francis" <alistair.francis@wdc.com>,
"Bin Meng" <bin.meng@windriver.com>,
"Weiwei Li" <liwei1518@gmail.com>,
"Daniel Henrique Barboza" <dbarboza@ventanamicro.com>,
"Liu Zhiwei" <zhiwei_liu@linux.alibaba.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Junqiang Wang" <wangjunqiang@iscas.ac.cn>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>
Subject: Re: [PATCH v2] target/riscv: Update $ra with current $pc in trans_cm_jalt()
Date: Thu, 15 Feb 2024 19:53:43 +1000 [thread overview]
Message-ID: <CAKmqyKPZ9-vWgk3R5vupZw3Zbi1PBvRtxQHUaFnfSwHT2UwYmQ@mail.gmail.com> (raw)
In-Reply-To: <20240207081820.28559-1-jason.chien@sifive.com>
On Wed, Feb 7, 2024 at 6:18 PM Jason Chien <jason.chien@sifive.com> wrote:
>
> The original implementation sets $pc to the address read from the jump
> vector table first and links $ra with the address of the next instruction
> after the updated $pc. After jumping to the updated $pc and executing the
> next ret instruction, the program jumps to $ra, which is in the same
> function currently executing, which results in an infinite loop.
> This commit stores the jump address in a temporary, updates $ra with the
> current $pc, and copies the temporary to $pc.
>
> Signed-off-by: Jason Chien <jason.chien@sifive.com>
> Reviewed-by: Frank Chang <frank.chang@sifive.com>
Thanks!
Applied to riscv-to-apply.next
Alistair
> ---
> target/riscv/insn_trans/trans_rvzce.c.inc | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/insn_trans/trans_rvzce.c.inc b/target/riscv/insn_trans/trans_rvzce.c.inc
> index 2d992e14c4..cd234ad960 100644
> --- a/target/riscv/insn_trans/trans_rvzce.c.inc
> +++ b/target/riscv/insn_trans/trans_rvzce.c.inc
> @@ -293,12 +293,14 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a)
> {
> REQUIRE_ZCMT(ctx);
>
> + TCGv addr = tcg_temp_new();
> +
> /*
> * Update pc to current for the non-unwinding exception
> * that might come from cpu_ld*_code() in the helper.
> */
> gen_update_pc(ctx, 0);
> - gen_helper_cm_jalt(cpu_pc, tcg_env, tcg_constant_i32(a->index));
> + gen_helper_cm_jalt(addr, tcg_env, tcg_constant_i32(a->index));
>
> /* c.jt vs c.jalt depends on the index. */
> if (a->index >= 32) {
> @@ -307,6 +309,8 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a)
> gen_set_gpr(ctx, xRA, succ_pc);
> }
>
> + tcg_gen_mov_tl(cpu_pc, addr);
> +
> tcg_gen_lookup_and_goto_ptr();
> ctx->base.is_jmp = DISAS_NORETURN;
> return true;
> --
> 2.43.0
>
>
prev parent reply other threads:[~2024-02-15 9:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-07 8:18 [PATCH v2] target/riscv: Update $ra with current $pc in trans_cm_jalt() Jason Chien
2024-02-08 19:31 ` Richard Henderson
2024-02-15 9:53 ` Alistair Francis [this message]
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