2019-12-06 13:31:56

by Andrey Konovalov

Subject: [PATCH v2] kcov: fix struct layout for kcov_remote_arg

Make the layout of kcov_remote_arg the same for 32-bit and 64-bit code.
This makes it more convenient to write userspace apps that can be compiled
into 32-bit or 64-bit binaries and still work with the same 64-bit kernel.
Also use proper __u32 types in uapi headers instead of unsigned ints.

Signed-off-by: Andrey Konovalov <[email protected]>
---

Changes v1->v2:
- Use __aligned_u64 instead of adding a __u32 reserved field.

Documentation/dev-tools/kcov.rst | 10 +++++-----
include/uapi/linux/kcov.h | 10 +++++-----
2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst
index 36890b026e77..1c4e1825d769 100644
--- a/Documentation/dev-tools/kcov.rst
+++ b/Documentation/dev-tools/kcov.rst
@@ -251,11 +251,11 @@ selectively from different subsystems.
.. code-block:: c

struct kcov_remote_arg {
- unsigned trace_mode;
- unsigned area_size;
- unsigned num_handles;
- uint64_t common_handle;
- uint64_t handles[0];
+ __u32 trace_mode;
+ __u32 area_size;
+ __u32 num_handles;
+ __aligned_u64 common_handle;
+ __aligned_u64 handles[0];
};

#define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
diff --git a/include/uapi/linux/kcov.h b/include/uapi/linux/kcov.h
index 409d3ad1e6e2..1d0350e44ae3 100644
--- a/include/uapi/linux/kcov.h
+++ b/include/uapi/linux/kcov.h
@@ -9,11 +9,11 @@
* and the comment before kcov_remote_start() for usage details.
*/
struct kcov_remote_arg {
- unsigned int trace_mode; /* KCOV_TRACE_PC or KCOV_TRACE_CMP */
- unsigned int area_size; /* Length of coverage buffer in words */
- unsigned int num_handles; /* Size of handles array */
- __u64 common_handle;
- __u64 handles[0];
+ __u32 trace_mode; /* KCOV_TRACE_PC or KCOV_TRACE_CMP */
+ __u32 area_size; /* Length of coverage buffer in words */
+ __u32 num_handles; /* Size of handles array */
+ __aligned_u64 common_handle;
+ __aligned_u64 handles[0];
};

#define KCOV_REMOTE_MAX_HANDLES 0x100
--
2.24.0.393.g34dc348eaf-goog

2019-12-06 13:47:02

by Marco Elver

Subject: Re: [PATCH v2] kcov: fix struct layout for kcov_remote_arg

On Fri, 6 Dec 2019 at 14:31, Andrey Konovalov <[email protected]> wrote:
>
> Make the layout of kcov_remote_arg the same for 32-bit and 64-bit code.
> This makes it more convenient to write userspace apps that can be compiled
> into 32-bit or 64-bit binaries and still work with the same 64-bit kernel.
> Also use proper __u32 types in uapi headers instead of unsigned ints.
>
> Signed-off-by: Andrey Konovalov <[email protected]>

Acked-by: Marco Elver <[email protected]>

Thanks!

> ---
>
> Changes v1->v2:
> - Use __aligned_u64 instead of adding a __u32 reserved field.
>
> Documentation/dev-tools/kcov.rst | 10 +++++-----
> include/uapi/linux/kcov.h | 10 +++++-----
> 2 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst
> index 36890b026e77..1c4e1825d769 100644
> --- a/Documentation/dev-tools/kcov.rst
> +++ b/Documentation/dev-tools/kcov.rst
> @@ -251,11 +251,11 @@ selectively from different subsystems.
> .. code-block:: c
>
> struct kcov_remote_arg {
> - unsigned trace_mode;
> - unsigned area_size;
> - unsigned num_handles;
> - uint64_t common_handle;
> - uint64_t handles[0];
> + __u32 trace_mode;
> + __u32 area_size;
> + __u32 num_handles;
> + __aligned_u64 common_handle;
> + __aligned_u64 handles[0];
> };
>
> #define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
> diff --git a/include/uapi/linux/kcov.h b/include/uapi/linux/kcov.h
> index 409d3ad1e6e2..1d0350e44ae3 100644
> --- a/include/uapi/linux/kcov.h
> +++ b/include/uapi/linux/kcov.h
> @@ -9,11 +9,11 @@
> * and the comment before kcov_remote_start() for usage details.
> */
> struct kcov_remote_arg {
> - unsigned int trace_mode; /* KCOV_TRACE_PC or KCOV_TRACE_CMP */
> - unsigned int area_size; /* Length of coverage buffer in words */
> - unsigned int num_handles; /* Size of handles array */
> - __u64 common_handle;
> - __u64 handles[0];
> + __u32 trace_mode; /* KCOV_TRACE_PC or KCOV_TRACE_CMP */
> + __u32 area_size; /* Length of coverage buffer in words */
> + __u32 num_handles; /* Size of handles array */
> + __aligned_u64 common_handle;
> + __aligned_u64 handles[0];
> };
>
> #define KCOV_REMOTE_MAX_HANDLES 0x100
> --
> 2.24.0.393.g34dc348eaf-goog
>