From: Jason Chien <jason.chien@sifive.com>
To: qemu-devel@nongnu.org, qemu-riscv@nongnu.org
Cc: Jason Chien <jason.chien@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Alistair Francis <alistair.francis@wdc.com>,
Bin Meng <bin.meng@windriver.com>,
Weiwei Li <liweiwei@iscas.ac.cn>,
Daniel Henrique Barboza <dbarboza@ventanamicro.com>,
Liu Zhiwei <zhiwei_liu@linux.alibaba.com>,
Junqiang Wang <wangjunqiang@iscas.ac.cn>,
Richard Henderson <richard.henderson@linaro.org>
Subject: [PATCH] target/riscv: Update $pc after linking to $ra in trans_cm_jalt()
Date: Tue, 6 Feb 2024 21:18:42 +0800 [thread overview]
Message-ID: <20240206131911.10998-1-jason.chien@sifive.com> (raw)
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 reverses the two action. Firstly, $ra is updated with the
address of the next instruction after $pc, and sets $pc to the address
read from the jump vector table.
Signed-off-by: Jason Chien <jason.chien@sifive.com>
---
target/riscv/insn_trans/trans_rvzce.c.inc | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/target/riscv/insn_trans/trans_rvzce.c.inc b/target/riscv/insn_trans/trans_rvzce.c.inc
index 8d8a64f493..a185e2315f 100644
--- a/target/riscv/insn_trans/trans_rvzce.c.inc
+++ b/target/riscv/insn_trans/trans_rvzce.c.inc
@@ -293,13 +293,6 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a)
{
REQUIRE_ZCMT(ctx);
- /*
- * 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, cpu_env, tcg_constant_i32(a->index));
-
/* c.jt vs c.jalt depends on the index. */
if (a->index >= 32) {
TCGv succ_pc = dest_gpr(ctx, xRA);
@@ -307,6 +300,13 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a)
gen_set_gpr(ctx, xRA, succ_pc);
}
+ /*
+ * 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, cpu_env, tcg_constant_i32(a->index));
+
tcg_gen_lookup_and_goto_ptr();
ctx->base.is_jmp = DISAS_NORETURN;
return true;
--
2.43.0
next reply other threads:[~2024-02-06 13:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-06 13:18 Jason Chien [this message]
2024-02-06 17:05 ` [PATCH] target/riscv: Update $pc after linking to $ra in trans_cm_jalt() Frank Chang
2024-02-06 20:24 ` Richard Henderson
2024-02-07 3:33 ` Jason Chien
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