On 11/17/22 23:17, Weiwei Li wrote:
+target_ulong HELPER(cm_jalt)(CPURISCVState *env, target_ulong index,
+ target_ulong next_pc)
+{
+
+#if !defined(CONFIG_USER_ONLY)
+ RISCVException ret = smstateen_acc_ok(env, 0, SMSTATEEN0_JVT);
+ if (ret != RISCV_EXCP_NONE) {
+ riscv_raise_exception(env, ret, GETPC());
+ }
+#endif
+
+ target_ulong target = next_pc;
+ target_ulong val = 0;
+ int xlen = riscv_cpu_xlen(env);
+
+ val = env->jvt;
+
+ uint8_t mode = get_field(val, JVT_MODE);
+ target_ulong base = get_field(val, JVT_BASE);
+ target_ulong t0;
+
+ if (mode != 0) {
+ riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
+ }
+
+ if (xlen == 32) {
+ t0 = base + (index << 2);
+ target = cpu_ldl_code(env, t0);
+ } else {
+ t0 = base + (index << 3);
+ target = cpu_ldq_code(env, t0);
+ }
Much better. The only problem is here where cpu_ld*_code does not
have support for unwind from exception. If this load faults, we won't
update env->pc on the way out (we are normally loading for code during
translation, where pc is perforce up to date). I should have noticed
this before.
The way to fix this is to update cpu_pc to the current instruction
before calling the helper. At which point none of the other exception
exits need to unwind either, so you can replace all of the GETPC()
with 0.
+
+ /* index >= 32 for cm.jalt, otherwise for cm.jt */
+ if (index >= 32) {
+ env->gpr[1] = next_pc;
+ }
This is simple enough to do in the caller, and then you don't need to
pass in next_pc.
And since you don't modify xRA in the helper you can do
DEF_HELPER_FLAGS_3(cm_jt, TCG_CALL_NO_WG, tl, env, tl, tl)
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.
*/
tcg_gen_movi_tl(cpu_pc, s->base.pc_next);
gen_helper_cm_jt(cpu_pc, cpu_env, tcg_constant_i32(a->index))
/* c.jt vs c.jalt depends on the index. */
if (a->index >= 32) {
gen_set_gpri(ctx, xRA, ctx->pc_succ_insn);
}
tcg_gen_lookup_and_goto_ptr();
ctx->base.is_jmp = DISAS_NORETURN;
return true;
}