[PATCH v2] Linux: Adjust struct rseq definition to current kernel version

[Carlos O'Donell]

On 6/2/22 10:26, Florian Weimer wrote:
> This definition is only used as a fallback with old kernel headers.
> The change follows kernel commit bfdf4e6208051ed7165b2e92035b4bf11
> ("rseq: Remove broken uapi field layout on 32-bit little endian").

LGTM.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
> v2: Drop #include <bits/endian.h>.  Use uint64_t instead of __u64.
> 
>  sysdeps/unix/sysv/linux/sys/rseq.h | 28 ++++++----------------------
>  1 file changed, 6 insertions(+), 22 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/sys/rseq.h b/sysdeps/unix/sysv/linux/sys/rseq.h
> index 8533782cf4..899d534df8 100644
> --- a/sysdeps/unix/sysv/linux/sys/rseq.h
> +++ b/sysdeps/unix/sysv/linux/sys/rseq.h
> @@ -24,7 +24,6 @@
>  #include <stddef.h>
>  #include <stdint.h>
>  #include <sys/cdefs.h>
> -#include <bits/endian.h>

OK. Drop endian.h since it's not needed any longer.

>  
>  #ifdef __has_include
>  # if __has_include ("linux/rseq.h")
> @@ -129,28 +128,13 @@ struct rseq
>         targeted by the rseq_cs.  Also needs to be set to NULL by user-space
>         before reclaiming memory that contains the targeted struct rseq_cs.
>  
> -       Read and set by the kernel.  Set by user-space with single-copy
> -       atomicity semantics.  This field should only be updated by the
> -       thread which registered this data structure.  Aligned on 64-bit.  */
> -    union
> -      {
> -        uint64_t ptr64;

OK. Upstream drops the entire union and leaves only the first element.

> -# ifdef __LP64__
> -        uint64_t ptr;
> -# else /* __LP64__ */
> -        struct
> -          {
> -#if __BYTE_ORDER == __BIG_ENDIAN
> -            uint32_t padding; /* Initialized to zero.  */
> -            uint32_t ptr32;
> -#  else /* LITTLE */
> -            uint32_t ptr32;
> -            uint32_t padding; /* Initialized to zero.  */
> -#  endif /* ENDIAN */
> -          } ptr;
> -# endif /* __LP64__ */
> -      } rseq_cs;
> +       Read and set by the kernel. Set by user-space with single-copy
> +       atomicity semantics. This field should only be updated by the
> +       thread which registered this data structure. Aligned on 64-bit.
>  
> +       32-bit architectures should update the low order bits of the
> +       rseq_cs field, leaving the high order bits initialized to 0.  */

OK. This matches upstream text.

> +    uint64_t rseq_cs;

OK. This matches the first element of the union (as upstream did).

>      /* Restartable sequences flags field.
>  
>         This field should only be updated by the thread which
> 


-- 
Cheers,
Carlos.