Implement compat sys_call_table and some system call functions:
truncate64, ftruncate64, fallocate, pread64, pwrite64,
sync_file_range, readahead, fadvise64_64 which need argument
translation.

Signed-off-by: Guo Ren <redacted>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>

This all looks really good, but I would change one detail:

+#ifndef compat_arg_u64
+#define compat_arg_u64(name)           u32  name##_lo, u32  name##_hi
+#define compat_arg_u64_dual(name)      u32, name##_lo, u32, name##_hi
+#define compat_arg_u64_glue(name)      (((u64)name##_hi << 32) | \
+                                        ((u64)name##_lo & 0xffffffffUL))
+#endif

I would make these endian-specific, and reverse them on big-endian
architectures. That way it
should be possible to share them across all compat architectures
without needing the override
option.

        Arnd