RE: [PATCH 07/39] target/hexagon: Implement wait helper

[<ltaylorsimpson@gmail.com>]

> -----Original Message-----
> From: Brian Cain <brian.cain@oss.qualcomm.com>
> Sent: Friday, February 28, 2025 11:28 PM
> To: qemu-devel@nongnu.org
> Cc: brian.cain@oss.qualcomm.com; richard.henderson@linaro.org;
> philmd@linaro.org; quic_mathbern@quicinc.com; ale@rev.ng; anjo@rev.ng;
> quic_mliebel@quicinc.com; ltaylorsimpson@gmail.com;
> alex.bennee@linaro.org; quic_mburton@quicinc.com;
> sidneym@quicinc.com; Brian Cain <bcain@quicinc.com>
> Subject: [PATCH 07/39] target/hexagon: Implement wait helper
> 
> From: Brian Cain <bcain@quicinc.com>
> 
> Signed-off-by: Brian Cain <brian.cain@oss.qualcomm.com>
> ---
>  target/hexagon/cpu_helper.h |  1 +
>  target/hexagon/cpu_helper.c | 40
> +++++++++++++++++++++++++++++++++++++
>  target/hexagon/op_helper.c  |  6 +++++-
>  3 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/target/hexagon/cpu_helper.h b/target/hexagon/cpu_helper.h
> index 95a0cc0788..e8d89d8526 100644
> --- a/target/hexagon/cpu_helper.h
> +++ b/target/hexagon/cpu_helper.h
> @@ -20,6 +20,7 @@ void clear_wait_mode(CPUHexagonState *env);  void
> hexagon_ssr_set_cause(CPUHexagonState *env, uint32_t cause);  void
> hexagon_start_threads(CPUHexagonState *env, uint32_t mask);  void
> hexagon_stop_thread(CPUHexagonState *env);
> +void hexagon_wait_thread(CPUHexagonState *env, target_ulong PC);
> 
>  static inline void arch_set_thread_reg(CPUHexagonState *env, uint32_t reg,
>                                         uint32_t val) diff --git a/target/hexagon/cpu_helper.c
> b/target/hexagon/cpu_helper.c index 3e2364a7b0..e64568b9fc 100644
> --- a/target/hexagon/cpu_helper.c
> +++ b/target/hexagon/cpu_helper.c
> @@ -71,6 +71,46 @@ void
> hexagon_set_sys_pcycle_count(CPUHexagonState *env, uint64_t cycles)
>      g_assert_not_reached();
>  }
> 
> +static void set_wait_mode(CPUHexagonState *env) {
> +    g_assert(bql_locked());
> +
> +    const uint32_t modectl = arch_get_system_reg(env,
> HEX_SREG_MODECTL);
> +    uint32_t thread_wait_mask = GET_FIELD(MODECTL_W, modectl);
> +    thread_wait_mask |= 0x1 << env->threadId;
> +    SET_SYSTEM_FIELD(env, HEX_SREG_MODECTL, MODECTL_W,
> +thread_wait_mask); }
> +
> +void hexagon_wait_thread(CPUHexagonState *env, target_ulong PC) {
> +    g_assert(bql_locked());
> +
> +    if (qemu_loglevel_mask(LOG_GUEST_ERROR) &&
> +        (env->k0_lock_state != HEX_LOCK_UNLOCKED ||
> +         env->tlb_lock_state != HEX_LOCK_UNLOCKED)) {
> +        qemu_log("WARNING: executing wait() with acquired lock"
> +                 "may lead to deadlock\n");
> +    }
> +    g_assert(get_exe_mode(env) != HEX_EXE_MODE_WAIT);
> +
> +    CPUState *cs = env_cpu(env);
> +    /*
> +     * The addtion of cpu_has_work is borrowed from arm's wfi helper
> +     * and is critical for our stability
> +     */
> +    if ((cs->exception_index != HEX_EVENT_NONE) ||
> +        (cpu_has_work(cs))) {
> +        qemu_log_mask(CPU_LOG_INT,
> +            "%s: thread %d skipping WAIT mode, have some work\n",
> +            __func__, env->threadId);
> +        return;
> +    }
> +    set_wait_mode(env);
> +    env->wait_next_pc = PC + 4;
> +
> +    cpu_interrupt(cs, CPU_INTERRUPT_HALT); }
> +

Why not put this in op_helper.c?

Otherwise
Reviewed-by: Taylor Simpson <ltaylorsimpson@gmail.com>