You are right. I'll send patch v2 shortly. Thank you for the reply.
On 2/6/24 23:18, Jason Chien 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 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.
This is unlikely to be correct in the case the vector table read faults,
leaving $ra updated.
I guess this got broken with CF_PCREL. Anyway, the solution is to use a temporary...
> - /*
> - * 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));
... here and then ...
> @@ -307,6 +300,13 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a)
> gen_set_gpr(ctx, xRA, succ_pc);
> }
>
... copy the temp to cpu_pc here.
> tcg_gen_lookup_and_goto_ptr();
> ctx->base.is_jmp = DISAS_NORETURN;
> return true;
r~