[PULL,01/34] target/riscv: Update $ra with current $pc in trans_cm_jalt()

Commit Message

Alistair Francis March 8, 2024, 11:11 a.m. UTC

From: Jason Chien <[e-mail]>

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 <[e-mail]>
Reviewed-by: Frank Chang <[e-mail]>
Reviewed-by: Richard Henderson <[e-mail]>
Message-ID: <[e-mail]>
Signed-off-by: Alistair Francis <[e-mail]>
---
 target/riscv/insn_trans/trans_rvzce.c.inc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Patch

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;