Peter Maydell <[email protected]> writes:
> 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...
I thought that was the right way round - it doesn't write to any
globals, but it does read so the helper needs to ensure globals are
synced before the callback.
>
>> 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
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
