* [PATCH][next] drm/amd/pm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE
@ 2021-02-10 22:40 Gustavo A. R. Silva
2021-02-15 18:56 ` Alex Deucher
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2021-02-10 22:40 UTC (permalink / raw)
To: Evan Quan, Alex Deucher, Christian König, David Airlie,
Daniel Vetter
Cc: amd-gfx, dri-devel, linux-kernel, Gustavo A. R. Silva, linux-hardening
There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].
Refactor the code according to the use of a flexible-array member in
struct SISLANDS_SMC_SWSTATE, instead of a one-element array, and use
the struct_size() helper to calculate the size for the allocation.
Also, this helps with the ongoing efforts to enable -Warray-bounds and
fix the following warnings:
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2448:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2449:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2450:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2451:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2452:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:5570:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/6023be58.sk66L%2FV4vuSJI5mI%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/gpu/drm/amd/pm/powerplay/si_dpm.c | 6 ++----
drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h | 10 +++++-----
2 files changed, 7 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c b/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
index afa1711c9620..62291358fb1c 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
@@ -5715,11 +5715,9 @@ static int si_upload_sw_state(struct amdgpu_device *adev,
int ret;
u32 address = si_pi->state_table_start +
offsetof(SISLANDS_SMC_STATETABLE, driverState);
- u32 state_size = sizeof(SISLANDS_SMC_SWSTATE) +
- ((new_state->performance_level_count - 1) *
- sizeof(SISLANDS_SMC_HW_PERFORMANCE_LEVEL));
SISLANDS_SMC_SWSTATE *smc_state = &si_pi->smc_statetable.driverState;
-
+ size_t state_size = struct_size(smc_state, levels,
+ new_state->performance_level_count);
memset(smc_state, 0, state_size);
ret = si_convert_power_state_to_smc(adev, amdgpu_new_state, smc_state);
diff --git a/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h b/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
index d2930eceaf3c..0f7554052c90 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
+++ b/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
@@ -182,11 +182,11 @@ typedef struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL SISLANDS_SMC_HW_PERFORMANCE_LEV
struct SISLANDS_SMC_SWSTATE
{
- uint8_t flags;
- uint8_t levelCount;
- uint8_t padding2;
- uint8_t padding3;
- SISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[1];
+ uint8_t flags;
+ uint8_t levelCount;
+ uint8_t padding2;
+ uint8_t padding3;
+ SISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[];
};
typedef struct SISLANDS_SMC_SWSTATE SISLANDS_SMC_SWSTATE;
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][next] drm/amd/pm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE
2021-02-10 22:40 [PATCH][next] drm/amd/pm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE Gustavo A. R. Silva
@ 2021-02-15 18:56 ` Alex Deucher
0 siblings, 0 replies; 2+ messages in thread
From: Alex Deucher @ 2021-02-15 18:56 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Evan Quan, Alex Deucher, Christian König, David Airlie,
Daniel Vetter, linux-hardening, Maling list - DRI developers,
amd-gfx list, LKML
On Wed, Feb 10, 2021 at 5:40 PM Gustavo A. R. Silva
<gustavoars@kernel.org> wrote:
>
> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use “flexible array members”[1] for these cases. The older
> style of one-element or zero-length arrays should no longer be used[2].
>
> Refactor the code according to the use of a flexible-array member in
> struct SISLANDS_SMC_SWSTATE, instead of a one-element array, and use
> the struct_size() helper to calculate the size for the allocation.
>
> Also, this helps with the ongoing efforts to enable -Warray-bounds and
> fix the following warnings:
>
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2448:20: warning: array
> subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
> {aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2449:20: warning: array
> subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
> {aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2450:20: warning: array
> subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
> {aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2451:20: warning: array
> subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
> {aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2452:20: warning: array
> subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
> {aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:5570:20: warning: array
> subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
> {aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
>
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/109
> Build-tested-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/lkml/6023be58.sk66L%2FV4vuSJI5mI%25lkp@intel.com/
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Applied. Thanks!
Alex
> ---
> drivers/gpu/drm/amd/pm/powerplay/si_dpm.c | 6 ++----
> drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h | 10 +++++-----
> 2 files changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c b/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
> index afa1711c9620..62291358fb1c 100644
> --- a/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
> +++ b/drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
> @@ -5715,11 +5715,9 @@ static int si_upload_sw_state(struct amdgpu_device *adev,
> int ret;
> u32 address = si_pi->state_table_start +
> offsetof(SISLANDS_SMC_STATETABLE, driverState);
> - u32 state_size = sizeof(SISLANDS_SMC_SWSTATE) +
> - ((new_state->performance_level_count - 1) *
> - sizeof(SISLANDS_SMC_HW_PERFORMANCE_LEVEL));
> SISLANDS_SMC_SWSTATE *smc_state = &si_pi->smc_statetable.driverState;
> -
> + size_t state_size = struct_size(smc_state, levels,
> + new_state->performance_level_count);
> memset(smc_state, 0, state_size);
>
> ret = si_convert_power_state_to_smc(adev, amdgpu_new_state, smc_state);
> diff --git a/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h b/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
> index d2930eceaf3c..0f7554052c90 100644
> --- a/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
> +++ b/drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
> @@ -182,11 +182,11 @@ typedef struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL SISLANDS_SMC_HW_PERFORMANCE_LEV
>
> struct SISLANDS_SMC_SWSTATE
> {
> - uint8_t flags;
> - uint8_t levelCount;
> - uint8_t padding2;
> - uint8_t padding3;
> - SISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[1];
> + uint8_t flags;
> + uint8_t levelCount;
> + uint8_t padding2;
> + uint8_t padding3;
> + SISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[];
> };
>
> typedef struct SISLANDS_SMC_SWSTATE SISLANDS_SMC_SWSTATE;
> --
> 2.27.0
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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