On Tue, 24 Feb 2026 at 15:43, Alex Bennée <[email protected]> wrote:
>
> If we generate an exception for WFIT we could also fill out the rv/rn
> fields of the ISS. To facilitate this pass the register number
> directly and read the timeout value in the helper itself.
>
> Signed-off-by: Alex Bennée <[email protected]>
> ---
> target/arm/tcg/helper-defs.h | 2 +-
> target/arm/tcg/op_helper.c | 4 +++-
> target/arm/tcg/translate-a64.c | 2 +-
> 3 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/target/arm/tcg/helper-defs.h b/target/arm/tcg/helper-defs.h
> index 5a10a9fba3b..a9a062cf777 100644
> --- a/target/arm/tcg/helper-defs.h
> +++ b/target/arm/tcg/helper-defs.h
> @@ -55,7 +55,7 @@ DEF_HELPER_2(exception_pc_alignment, noreturn, env, vaddr)
> DEF_HELPER_1(setend, void, env)
> DEF_HELPER_2(wfi, void, env, i32)
> DEF_HELPER_1(wfe, void, env)
> -DEF_HELPER_2(wfit, void, env, i64)
> +DEF_HELPER_FLAGS_2(wfit, TCG_CALL_NO_WG, void, env, i32)
Why the change to NO_WG ? The code change doesn't remove any
writes to globals...
> DEF_HELPER_1(yield, void, env)
> DEF_HELPER_1(pre_hvc, void, env)
> DEF_HELPER_2(pre_smc, void, env, i32)
> diff --git a/target/arm/tcg/op_helper.c b/target/arm/tcg/op_helper.c
> index aa14f15eb62..28a1c7243ad 100644
> --- a/target/arm/tcg/op_helper.c
> +++ b/target/arm/tcg/op_helper.c
> @@ -409,7 +409,7 @@ void HELPER(wfi)(CPUARMState *env, uint32_t insn_len)
> #endif
> }
>
> -void HELPER(wfit)(CPUARMState *env, uint64_t timeout)
> +void HELPER(wfit)(CPUARMState *env, uint32_t rd)
> {
> #ifdef CONFIG_USER_ONLY
> /*
> @@ -428,6 +428,8 @@ void HELPER(wfit)(CPUARMState *env, uint64_t timeout)
> int target_el = check_wfx_trap(env, false, &excp);
> /* The WFIT should time out when CNTVCT_EL0 >= the specified value. */
> uint64_t cntval = gt_get_countervalue(env);
> + uint64_t timeout = env->xregs[rd];
> +
> /*
> * We want the value that we would get if we read CNTVCT_EL0 from
> * the current exception level, so the direct_access offset, not
> diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
> index 5d261a5e32b..073454b9195 100644
> --- a/target/arm/tcg/translate-a64.c
> +++ b/target/arm/tcg/translate-a64.c
> @@ -2064,7 +2064,7 @@ static bool trans_WFIT(DisasContext *s, arg_WFIT *a)
> }
>
> gen_a64_update_pc(s, 4);
> - gen_helper_wfit(tcg_env, cpu_reg(s, a->rd));
> + gen_helper_wfit(tcg_env, tcg_constant_i32(a->rd));
> /* Go back to the main loop to check for interrupts */
> s->base.is_jmp = DISAS_EXIT;
> return true;
Otherwise
Reviewed-by: Peter Maydell <[email protected]>
You might squash this in to patch 4 if you like.
thanks
-- PMM
