arm64: fix COMPAT_SHMLBA definition for large pages

ARM glibc uses (4 * __getpagesize()) for SHMLBA, which is correct for
4KB pages and works fine for 64KB pages, but the kernel uses a hardcoded
16KB that is too small for 64KB page based kernels. This changes the
definition to what user space sees when using 64KB pages.

Acked-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Yury Norov <[e-mail]>
Signed-off-by: Will Deacon <[e-mail]>

arch/arm64/include/asm/shmparam.h

···
  * alignment value. Since we don't have aliasing D-caches, the rest of
  * the time we can safely use PAGE_SIZE.
  */
-#define COMPAT_SHMLBA	0x4000
+#define COMPAT_SHMLBA	(4 * PAGE_SIZE)
 
 #include <asm-generic/shmparam.h>