Compiling the kernel with gcc12.3 W=2 results in shadowing warnings:

warning: declaration of '__pptr' shadows a previous local [-Wshadow]
  const struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr);

note: in definition of macro '__put_unaligned_t'
  __pptr->x = (val);

note: in expansion of macro '__get_unaligned_t'
  __put_unaligned_t(type, __get_unaligned_t(type, src), dst);

__get_unaligned_t() and __put_unaligned_t() use a local variable named
'__pptr', which can lead to variable shadowing when these macros are used in
the same scope. This results in a -Wshadow warning during compilation.

To address this issue, rename the local variables within the macros to
ensure uniqueness.

Signed-off-by: Peng Jiang <jiang.peng9@zte.com.cn>
Signed-off-by: Shao Mingyin <shao.mingyin@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250324191230477zpGtgIRSH4mEHdtxGtgx9@zte.com.cn

Depending on the architecture, building a 32-bit vDSO on a 64-bit kernel
is problematic when some system headers are included.

Minimise the amount of headers by moving needed items, such as
__{get,put}_unaligned_t, into dedicated common headers and in general
use more specific headers, similar to what was done in commit
8165b57bca21 ("linux/const.h: Extract common header for vDSO") and
commit 8c59ab839f52 ("lib/vdso: Enable common headers").

On some architectures this results in missing PAGE_SIZE, as was
described by commit 8b3843ae3634 ("vdso/datapage: Quick fix - use
asm/page-def.h for ARM64"), so define this if necessary, in the same way
as done prior by commit cffaefd15a8f ("vdso: Use CONFIG_PAGE_SHIFT in
vdso/datapage.h").

Removing linux/time64.h leads to missing 'struct timespec64' in
x86's asm/pvclock.h. Add a forward declaration of that struct in
that file.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>