x86/syscalls: Add compat_sys_preadv64v2/compat_sys_pwritev64v2

Don't use the same syscall numbers for 2 different syscalls:

 534	x32	preadv			compat_sys_preadv64
 535	x32	pwritev			compat_sys_pwritev64
 534	x32	preadv2			compat_sys_preadv2
 535	x32	pwritev2		compat_sys_pwritev2

Add compat_sys_preadv64v2() and compat_sys_pwritev64v2() so that 64-bit offset
is passed in one 64-bit register on x32, similar to compat_sys_preadv64()
and compat_sys_pwritev64().

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/CAMe9rOovCMf-RQfx_n1U_Tu_DX1BYkjtFr%3DQ4-_PFVSj9BCzUA@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/entry/syscalls/syscall_64.tbl

@@ -374,5 +374,5 @@
 543	x32	io_setup		compat_sys_io_setup
 544	x32	io_submit		compat_sys_io_submit
 545	x32	execveat		compat_sys_execveat/ptregs
-534	x32	preadv2			compat_sys_preadv2
-535	x32	pwritev2		compat_sys_pwritev2
+546	x32	preadv2			compat_sys_preadv64v2
+547	x32	pwritev2		compat_sys_pwritev64v2

arch/x86/include/asm/unistd.h

@@ -26,6 +26,8 @@
 #  define __ARCH_WANT_COMPAT_SYS_GETDENTS64
 #  define __ARCH_WANT_COMPAT_SYS_PREADV64
 #  define __ARCH_WANT_COMPAT_SYS_PWRITEV64
+#  define __ARCH_WANT_COMPAT_SYS_PREADV64V2
+#  define __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
 
 # endif
 

fs/read_write.c

@@ -1168,6 +1168,15 @@ COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
 	return do_compat_preadv64(fd, vec, vlen, pos, 0);
 }
 
+#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
+COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
+		const struct compat_iovec __user *,vec,
+		unsigned long, vlen, loff_t, pos, int, flags)
+{
+	return do_compat_preadv64(fd, vec, vlen, pos, flags);
+}
+#endif
+
 COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
 		const struct compat_iovec __user *,vec,
 		compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
@@ -1265,6 +1274,15 @@ COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
 	return do_compat_pwritev64(fd, vec, vlen, pos, 0);
 }
 
+#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
+COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
+		const struct compat_iovec __user *,vec,
+		unsigned long, vlen, loff_t, pos, int, flags)
+{
+	return do_compat_pwritev64(fd, vec, vlen, pos, flags);
+}
+#endif
+
 COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
 		const struct compat_iovec __user *,vec,
 		compat_ulong_t, vlen, u32, pos_low, u32, pos_high, int, flags)