linux-kernel - Re: [PATCH] drm/amd/pm: avoid large variable on kernel stack

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Message-ID: <CADnq5_P0M5fYCbqt+PwLSGzdeMy3YCvkaRW9sm+z7rC0Ra8_mw@mail.gmail.com>
Date:   Thu, 15 Dec 2022 13:45:16 -0500
From:   Alex Deucher <alexdeucher@...il.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Evan Quan <evan.quan@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        Kenneth Feng <kenneth.feng@....com>,
        Yang Wang <KevinYang.Wang@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Chengming Gui <Jack.Gui@....com>, Tom Rix <trix@...hat.com>,
        llvm@...ts.linux.dev, Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        Nathan Chancellor <nathan@...nel.org>,
        dri-devel@...ts.freedesktop.org,
        Hawking Zhang <Hawking.Zhang@....com>
Subject: Re: [PATCH] drm/amd/pm: avoid large variable on kernel stack

Applied.  Thanks!

Alex

On Thu, Dec 15, 2022 at 11:37 AM Arnd Bergmann <arnd@...nel.org> wrote:
>
> From: Arnd Bergmann <arnd@...db.de>
>
> The activity_monitor_external[] array is too big to fit on the
> kernel stack, resulting in this warning with clang:
>
> drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu13/smu_v13_0_7_ppt.c:1438:12: error: stack frame size (1040) exceeds limit (1024) in 'smu_v13_0_7_get_power_profile_mode' [-Werror,-Wframe-larger-than]
>
> Use dynamic allocation instead. It should also be possible to
> have single element here instead of the array, but this seems
> easier.
>
> Fixes: 334682ae8151 ("drm/amd/pm: enable workload type change on smu_v13_0_7")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  .../drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c  | 21 ++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
> index c270f94a1b86..7eba854e09ec 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
> @@ -1439,7 +1439,7 @@ static int smu_v13_0_7_get_power_limit(struct smu_context *smu,
>
>  static int smu_v13_0_7_get_power_profile_mode(struct smu_context *smu, char *buf)
>  {
> -       DpmActivityMonitorCoeffIntExternal_t activity_monitor_external[PP_SMC_POWER_PROFILE_COUNT];
> +       DpmActivityMonitorCoeffIntExternal_t *activity_monitor_external;
>         uint32_t i, j, size = 0;
>         int16_t workload_type = 0;
>         int result = 0;
> @@ -1447,6 +1447,12 @@ static int smu_v13_0_7_get_power_profile_mode(struct smu_context *smu, char *buf
>         if (!buf)
>                 return -EINVAL;
>
> +       activity_monitor_external = kcalloc(sizeof(activity_monitor_external),
> +                                           PP_SMC_POWER_PROFILE_COUNT,
> +                                           GFP_KERNEL);
> +       if (!activity_monitor_external)
> +               return -ENOMEM;
> +
>         size += sysfs_emit_at(buf, size, "                              ");
>         for (i = 0; i <= PP_SMC_POWER_PROFILE_WINDOW3D; i++)
>                 size += sysfs_emit_at(buf, size, "%-14s%s", amdgpu_pp_profile_name[i],
> @@ -1459,15 +1465,17 @@ static int smu_v13_0_7_get_power_profile_mode(struct smu_context *smu, char *buf
>                 workload_type = smu_cmn_to_asic_specific_index(smu,
>                                                                CMN2ASIC_MAPPING_WORKLOAD,
>                                                                i);
> -               if (workload_type < 0)
> -                       return -EINVAL;
> +               if (workload_type < 0) {
> +                       result = -EINVAL;
> +                       goto out;
> +               }
>
>                 result = smu_cmn_update_table(smu,
>                                           SMU_TABLE_ACTIVITY_MONITOR_COEFF, workload_type,
>                                           (void *)(&activity_monitor_external[i]), false);
>                 if (result) {
>                         dev_err(smu->adev->dev, "[%s] Failed to get activity monitor!", __func__);
> -                       return result;
> +                       goto out;
>                 }
>         }
>
> @@ -1495,7 +1503,10 @@ do {                                                                                                     \
>         PRINT_DPM_MONITOR(Fclk_BoosterFreq);
>  #undef PRINT_DPM_MONITOR
>
> -       return size;
> +       result = size;
> +out:
> +       kfree(activity_monitor_external);
> +       return result;
>  }
>
>  static int smu_v13_0_7_set_power_profile_mode(struct smu_context *smu, long *input, uint32_t size)
> --
> 2.35.1
>