[PATCH][next] drm/radeon/si_dpm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE
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 by fixing the following warnings:
drivers/gpu/drm/radeon/si_dpm.c: In function ‘si_convert_power_state_to_smc’: drivers/gpu/drm/radeon/si_dpm.c:2350:20: 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] 2350 | smc_state->levels[i].dpm2.MaxPS = (u8)((SISLANDS_DPM2_MAX_PULSE_SKIP * (max_sclk - min_sclk)) / max_sclk); | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2351:20: 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] 2351 | smc_state->levels[i].dpm2.NearTDPDec = SISLANDS_DPM2_NEAR_TDP_DEC; | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2352:20: 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] 2352 | smc_state->levels[i].dpm2.AboveSafeInc = SISLANDS_DPM2_ABOVE_SAFE_INC; | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2353:20: 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] 2353 | smc_state->levels[i].dpm2.BelowSafeInc = SISLANDS_DPM2_BELOW_SAFE_INC; | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2354:20: 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] 2354 | smc_state->levels[i].dpm2.PwrEfficiencyRatio = cpu_to_be16(pwr_efficiency_ratio); | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:5105:20: 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] 5105 | smc_state->levels[i + 1].aT = cpu_to_be32(a_t); | ~~~~~~~~~~~~~~~~~^~~~~~~
[1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and...
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/603f9a8f.aDLrpMFzzSApzVYQ%25lkp@intel.com/ Signed-off-by: Gustavo A. R. Silva gustavoars@kernel.org --- drivers/gpu/drm/radeon/si_dpm.c | 5 ++--- drivers/gpu/drm/radeon/sislands_smc.h | 10 +++++----- 2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/radeon/si_dpm.c b/drivers/gpu/drm/radeon/si_dpm.c index 91bfc4762767..918609551804 100644 --- a/drivers/gpu/drm/radeon/si_dpm.c +++ b/drivers/gpu/drm/radeon/si_dpm.c @@ -5250,10 +5250,9 @@ static int si_upload_sw_state(struct radeon_device *rdev, 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);
diff --git a/drivers/gpu/drm/radeon/sislands_smc.h b/drivers/gpu/drm/radeon/sislands_smc.h index 966e3a556011..fbd6589bdab9 100644 --- a/drivers/gpu/drm/radeon/sislands_smc.h +++ b/drivers/gpu/drm/radeon/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;
Applied. Thanks!
Alex
On Wed, Mar 3, 2021 at 2:05 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 by fixing the following warnings:
drivers/gpu/drm/radeon/si_dpm.c: In function ‘si_convert_power_state_to_smc’: drivers/gpu/drm/radeon/si_dpm.c:2350:20: 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] 2350 | smc_state->levels[i].dpm2.MaxPS = (u8)((SISLANDS_DPM2_MAX_PULSE_SKIP * (max_sclk - min_sclk)) / max_sclk); | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2351:20: 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] 2351 | smc_state->levels[i].dpm2.NearTDPDec = SISLANDS_DPM2_NEAR_TDP_DEC; | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2352:20: 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] 2352 | smc_state->levels[i].dpm2.AboveSafeInc = SISLANDS_DPM2_ABOVE_SAFE_INC; | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2353:20: 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] 2353 | smc_state->levels[i].dpm2.BelowSafeInc = SISLANDS_DPM2_BELOW_SAFE_INC; | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:2354:20: 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] 2354 | smc_state->levels[i].dpm2.PwrEfficiencyRatio = cpu_to_be16(pwr_efficiency_ratio); | ~~~~~~~~~~~~~~~~~^~~ drivers/gpu/drm/radeon/si_dpm.c:5105:20: 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] 5105 | smc_state->levels[i + 1].aT = cpu_to_be32(a_t); | ~~~~~~~~~~~~~~~~~^~~~~~~
[1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and...
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/603f9a8f.aDLrpMFzzSApzVYQ%25lkp@intel.com/ Signed-off-by: Gustavo A. R. Silva gustavoars@kernel.org
drivers/gpu/drm/radeon/si_dpm.c | 5 ++--- drivers/gpu/drm/radeon/sislands_smc.h | 10 +++++----- 2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/radeon/si_dpm.c b/drivers/gpu/drm/radeon/si_dpm.c index 91bfc4762767..918609551804 100644 --- a/drivers/gpu/drm/radeon/si_dpm.c +++ b/drivers/gpu/drm/radeon/si_dpm.c @@ -5250,10 +5250,9 @@ static int si_upload_sw_state(struct radeon_device *rdev, 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);diff --git a/drivers/gpu/drm/radeon/sislands_smc.h b/drivers/gpu/drm/radeon/sislands_smc.h index 966e3a556011..fbd6589bdab9 100644 --- a/drivers/gpu/drm/radeon/sislands_smc.h +++ b/drivers/gpu/drm/radeon/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
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Gustavo A. R. Silva