Re: [PATCH 1/3] xen/lzo: Implement COPY{4,8} using memcpy()

[Stefano Stabellini]

On Tue, 21 May 2024, Andrew Cooper wrote:
> This is simpler and easier for both humans and compilers to read.
> 
> It also addresses 6 instances of MISRA R5.3 violation (shadowing of the ptr_
> local variable inside both {put,get}_unaligned()).
> 
> No change, not even in the compiled binary.
> 
> Signed-off-by: Andrew Cooper 

Reviewed-by: Stefano Stabellini 


> ---
> CC: George Dunlap 
> CC: Jan Beulich 
> CC: Stefano Stabellini 
> CC: Julien Grall 
> CC: Roberto Bagnara 
> CC: consult...@bugseng.com 
> CC: Oleksii Kurochko 
> ---
>  xen/common/lzo.c | 11 ++-
>  1 file changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/xen/common/lzo.c b/xen/common/lzo.c
> index cc03f0f5547f..3454ce4a7e24 100644
> --- a/xen/common/lzo.c
> +++ b/xen/common/lzo.c
> @@ -25,15 +25,8 @@
>   */
>  
>  
> -#define COPY4(dst, src)\
> -put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst))
> -#if defined(__x86_64__)
> -#define COPY8(dst, src)\
> -put_unaligned(get_unaligned((const u64 *)(src)), (u64 *)(dst))
> -#else
> -#define COPY8(dst, src)\
> -COPY4(dst, src); COPY4((dst) + 4, (src) + 4)
> -#endif
> +#define COPY4(dst, src) memcpy(dst, src, 4)
> +#define COPY8(dst, src) memcpy(dst, src, 8)
>  
>  #ifdef __MINIOS__
>  # include 
> -- 
> 2.30.2
> 

[PATCH 1/3] xen/lzo: Implement COPY{4,8} using memcpy()

[Andrew Cooper]

This is simpler and easier for both humans and compilers to read.

It also addresses 6 instances of MISRA R5.3 violation (shadowing of the ptr_
local variable inside both {put,get}_unaligned()).

No change, not even in the compiled binary.

Signed-off-by: Andrew Cooper 
---
CC: George Dunlap 
CC: Jan Beulich 
CC: Stefano Stabellini 
CC: Julien Grall 
CC: Roberto Bagnara 
CC: consult...@bugseng.com 
CC: Oleksii Kurochko 
---
 xen/common/lzo.c | 11 ++-
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/xen/common/lzo.c b/xen/common/lzo.c
index cc03f0f5547f..3454ce4a7e24 100644
--- a/xen/common/lzo.c
+++ b/xen/common/lzo.c
@@ -25,15 +25,8 @@
  */
 
 
-#define COPY4(dst, src)\
-put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst))
-#if defined(__x86_64__)
-#define COPY8(dst, src)\
-put_unaligned(get_unaligned((const u64 *)(src)), (u64 *)(dst))
-#else
-#define COPY8(dst, src)\
-COPY4(dst, src); COPY4((dst) + 4, (src) + 4)
-#endif
+#define COPY4(dst, src) memcpy(dst, src, 4)
+#define COPY8(dst, src) memcpy(dst, src, 8)
 
 #ifdef __MINIOS__
 # include 
-- 
2.30.2