Hi,
On 10/05/2022 11:15, Lin Liu wrote:
> Update to use byteswap to swap bytes.
>
> No functional change.
>
> Signed-off-by: Lin Liu <lin.liu@xxxxxxxxxx>
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien@xxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
> Changes in v3:
> - Update xen/common/device_tree.c to use be32_to_cpu
> - Keep const in type cast in unaligned.h
> ---
> xen/common/device_tree.c | 44 +++++++++++++++---------------
> xen/common/libelf/libelf-private.h | 6 ++--
> xen/common/xz/private.h | 2 +-
> xen/include/xen/unaligned.h | 24 ++++++++--------
> 4 files changed, 38 insertions(+), 38 deletions(-)
>
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 4aae281e89..70d3be3be6 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -171,7 +171,7 @@ bool_t dt_property_read_u32(const struct dt_device_node *np,
> if ( !val || len < sizeof(*out_value) )
> return 0;
>
> - *out_value = be32_to_cpup(val);
> + *out_value = be32_to_cpu(*val);
> This code has been taken from Linux and I would rather prefer to keep
>the *cpup* helpers to avoid any changes when backporting.
> diff --git a/xen/include/xen/unaligned.h b/xen/include/xen/unaligned.h
> index 0a2b16d05d..16b2e6f5f0 100644
> --- a/xen/include/xen/unaligned.h
> +++ b/xen/include/xen/unaligned.h
> @@ -20,62 +20,62 @@
>
> static inline uint16_t get_unaligned_be16(const void *p)
> {
> - return be16_to_cpup(p);
> + return be16_to_cpu(*(const uint16_t *)p)
> I haven't checked the existing implementation of be16_to_cpup().
> However, this new approach would allow the compiler to use a single load
> instruction to read the 16-bit value from memory. So this change may
> break on platform where unaligned access is forbidden (such as arm32).
> }
>
> static inline void put_unaligned_be16(uint16_t val, void *p)
> {
> - *(__force __be16*)p = cpu_to_be16(val);
> + *(__be16 *)p = cpu_to_be16(val);
>> Why did you drop the __force?
Google told me __force is used in linux kernel to suppress warning in sparse,
https://stackoverflow.com/questions/53120610/what-does-the-attribute-force-do
Is sparse also used in xen?
> }
>
