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SubjectRe: [PATCH] drm/amd/pm: avoid large variable on kernel stack
On Thu, Dec 15, 2022 at 2:46 PM Christophe JAILLET
<christophe.jaillet@wanadoo.fr> wrote:
>
> Le 15/12/2022 à 17:36, Arnd Bergmann a écrit :
> > From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
> >
> > 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-r2nGTMty4D4@public.gmane.org>
> > ---
> > .../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),
>
> Hi,
>
> Before, 'activity_monitor_external' was not initialized.
> Maybe kcalloc() is enough?
>
> sizeof(*activity_monitor_external)?
> ~~~~

I've fixed this up when applying.

Alex

>
> > + 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++)
>
> Unrelated, but wouldn't it be more straightforward with "<
> PP_SMC_POWER_PROFILE_COUNT"?
>
> > 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)
>

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