Re: [PATCH] drm/radeon/dpm: Replace one-element array and use struct_size() helper

2020-05-22 Thread Gustavo A. R. Silva 
On Fri, May 22, 2020 at 09:00:09AM +0200, Christian König wrote:
> > +++ b/drivers/gpu/drm/radeon/ni_dpm.c
> > @@ -2685,11 +2685,12 @@ static int ni_upload_sw_state(struct radeon_device 
> > *rdev,
> > struct rv7xx_power_info *pi = rv770_get_pi(rdev);
> > u16 address = pi->state_table_start +
> > offsetof(NISLANDS_SMC_STATETABLE, driverState);
> > -   u16 state_size = sizeof(NISLANDS_SMC_SWSTATE) +
> > -   ((NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE - 1) * 
> > sizeof(NISLANDS_SMC_HW_PERFORMANCE_LEVEL));
> > +   NISLANDS_SMC_SWSTATE *smc_state;
> > +   u16 state_size = struct_size(smc_state, levels,
> > +   NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE);
> 
> Probably better to use size_t instead of u16 here. With that fixed feel free
> to stick my rb on the patch.
> 

Sure thing. I'll send v2, shortly.

Thanks, Christian.
--
Gustavo
___
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

Re: [PATCH] drm/radeon/dpm: Replace one-element array and use struct_size() helper

2020-05-22 Thread Christian König 

Am 22.05.20 um 03:25 schrieb Gustavo A. R. Silva:

The current codebase makes use of one-element arrays in the following
form:

struct something {
 int length;
 u8 data[1];
};

struct something *instance;

instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
instance->length = size;
memcpy(instance->data, source, size);

but the preferred mechanism to declare variable-length types such as
these ones is a flexible array member[1][2], introduced in C99:

struct foo {
 int stuff;
 struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on. So, replace
the one-element array with a flexible-array member.

Also, make use of the new struct_size() helper to properly calculate the
size of struct NISLANDS_SMC_SWSTATE.

This issue was found with the help of Coccinelle and, audited and fixed
_manually_.

[1] 
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fonlinedocs%2Fgcc%2FZero-Length.htmldata=02%7C01%7Cchristian.koenig%40amd.com%7C7dd54e944eff4d17178008d7fdee62d7%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637257072615411745sdata=fQHnbXZpsgiMjHOr%2By0Uq12jpCYEYbdX5K26iNkwyeM%3Dreserved=0
[2] 
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F21data=02%7C01%7Cchristian.koenig%40amd.com%7C7dd54e944eff4d17178008d7fdee62d7%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637257072615411745sdata=gg20YupmqsaW%2Bg3VyJL%2BkjE3kFwnWF1RD1D2QP04OLk%3Dreserved=0
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva 
---
  drivers/gpu/drm/amd/amdgpu/si_dpm.h | 2 +-
  drivers/gpu/drm/radeon/ni_dpm.c | 7 ---
  2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/si_dpm.h 
b/drivers/gpu/drm/amd/amdgpu/si_dpm.h
index 6b7d292b919f3..bc0be6818e218 100644
--- a/drivers/gpu/drm/amd/amdgpu/si_dpm.h
+++ b/drivers/gpu/drm/amd/amdgpu/si_dpm.h
@@ -781,7 +781,7 @@ struct NISLANDS_SMC_SWSTATE
  uint8_t levelCount;
  uint8_t padding2;
  uint8_t padding3;
-NISLANDS_SMC_HW_PERFORMANCE_LEVEL   levels[1];
+NISLANDS_SMC_HW_PERFORMANCE_LEVEL   levels[];
  };
  
  typedef struct NISLANDS_SMC_SWSTATE NISLANDS_SMC_SWSTATE;

diff --git a/drivers/gpu/drm/radeon/ni_dpm.c b/drivers/gpu/drm/radeon/ni_dpm.c
index b57c37ddd164c..7d81dde509dc9 100644
--- a/drivers/gpu/drm/radeon/ni_dpm.c
+++ b/drivers/gpu/drm/radeon/ni_dpm.c
@@ -2685,11 +2685,12 @@ static int ni_upload_sw_state(struct radeon_device 
*rdev,
struct rv7xx_power_info *pi = rv770_get_pi(rdev);
u16 address = pi->state_table_start +
offsetof(NISLANDS_SMC_STATETABLE, driverState);
-   u16 state_size = sizeof(NISLANDS_SMC_SWSTATE) +
-   ((NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE - 1) * 
sizeof(NISLANDS_SMC_HW_PERFORMANCE_LEVEL));
+   NISLANDS_SMC_SWSTATE *smc_state;
+   u16 state_size = struct_size(smc_state, levels,
+   NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE);


Probably better to use size_t instead of u16 here. With that fixed feel 
free to stick my rb on the patch.


Regards,
Christian.


int ret;
-   NISLANDS_SMC_SWSTATE *smc_state = kzalloc(state_size, GFP_KERNEL);
  
+	smc_state = kzalloc(state_size, GFP_KERNEL);

if (smc_state == NULL)
return -ENOMEM;
  


___
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

[PATCH] drm/radeon/dpm: Replace one-element array and use struct_size() helper

2020-05-21 Thread Gustavo A. R. Silva 
The current codebase makes use of one-element arrays in the following
form:

struct something {
int length;
u8 data[1];
};

struct something *instance;

instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
instance->length = size;
memcpy(instance->data, source, size);

but the preferred mechanism to declare variable-length types such as
these ones is a flexible array member[1][2], introduced in C99:

struct foo {
int stuff;
struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on. So, replace
the one-element array with a flexible-array member.

Also, make use of the new struct_size() helper to properly calculate the
size of struct NISLANDS_SMC_SWSTATE.

This issue was found with the help of Coccinelle and, audited and fixed
_manually_.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva 
---
 drivers/gpu/drm/amd/amdgpu/si_dpm.h | 2 +-
 drivers/gpu/drm/radeon/ni_dpm.c | 7 ---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/si_dpm.h 
b/drivers/gpu/drm/amd/amdgpu/si_dpm.h
index 6b7d292b919f3..bc0be6818e218 100644
--- a/drivers/gpu/drm/amd/amdgpu/si_dpm.h
+++ b/drivers/gpu/drm/amd/amdgpu/si_dpm.h
@@ -781,7 +781,7 @@ struct NISLANDS_SMC_SWSTATE
 uint8_t levelCount;
 uint8_t padding2;
 uint8_t padding3;
-NISLANDS_SMC_HW_PERFORMANCE_LEVEL   levels[1];
+NISLANDS_SMC_HW_PERFORMANCE_LEVEL   levels[];
 };
 
 typedef struct NISLANDS_SMC_SWSTATE NISLANDS_SMC_SWSTATE;
diff --git a/drivers/gpu/drm/radeon/ni_dpm.c b/drivers/gpu/drm/radeon/ni_dpm.c
index b57c37ddd164c..7d81dde509dc9 100644
--- a/drivers/gpu/drm/radeon/ni_dpm.c
+++ b/drivers/gpu/drm/radeon/ni_dpm.c
@@ -2685,11 +2685,12 @@ static int ni_upload_sw_state(struct radeon_device 
*rdev,
struct rv7xx_power_info *pi = rv770_get_pi(rdev);
u16 address = pi->state_table_start +
offsetof(NISLANDS_SMC_STATETABLE, driverState);
-   u16 state_size = sizeof(NISLANDS_SMC_SWSTATE) +
-   ((NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE - 1) * 
sizeof(NISLANDS_SMC_HW_PERFORMANCE_LEVEL));
+   NISLANDS_SMC_SWSTATE *smc_state;
+   u16 state_size = struct_size(smc_state, levels,
+   NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE);
int ret;
-   NISLANDS_SMC_SWSTATE *smc_state = kzalloc(state_size, GFP_KERNEL);
 
+   smc_state = kzalloc(state_size, GFP_KERNEL);
if (smc_state == NULL)
return -ENOMEM;
 
-- 
2.26.2

___
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx