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Linus Torvalds 601cc11d05 Make non-compat preadv/pwritev use native register size 
Instead of always splitting the file offset into 32-bit 'high' and 'low'
parts, just split them into the largest natural word-size - which in C
terms is 'unsigned long'.

This allows 64-bit architectures to avoid the unnecessary 32-bit
shifting and masking for native format (while the compat interfaces will
obviously always have to do it).

This also changes the order of 'high' and 'low' to be "low first".  Why?
Because when we have it like this, the 64-bit system calls now don't use
the "pos_high" argument at all, and it makes more sense for the native
system call to simply match the user-mode prototype.

This results in a much more natural calling convention, and allows the
compiler to generate much more straightforward code.  On x86-64, we now
generate

        testq   %rcx, %rcx      # pos_l
        js      .L122   #,
        movq    %rcx, -48(%rbp) # pos_l, pos

from the C source

        loff_t pos = pos_from_hilo(pos_h, pos_l);
	...
        if (pos < 0)
                return -EINVAL;

and the 'pos_h' register isn't even touched.  It used to generate code
like

        mov     %r8d, %r8d      # pos_low, pos_low
        salq    $32, %rcx       #, tmp71
        movq    %r8, %rax       # pos_low, pos.386
        orq     %rcx, %rax      # tmp71, pos.386
        js      .L122   #,
        movq    %rax, -48(%rbp) # pos.386, pos

which isn't _that_ horrible, but it does show how the natural word size
is just a more sensible interface (same arguments will hold in the user
level glibc wrapper function, of course, so the kernel side is just half
of the equation!)

Note: in all cases the user code wrapper can again be the same. You can
just do

	#define HALF_BITS (sizeof(unsigned long)*4)
	__syscall(PWRITEV, fd, iov, count, offset, (offset >> HALF_BITS) >> HALF_BITS);

or something like that.  That way the user mode wrapper will also be
nicely passing in a zero (it won't actually have to do the shifts, the
compiler will understand what is going on) for the last argument.

And that is a good idea, even if nobody will necessarily ever care: if
we ever do move to a 128-bit lloff_t, this particular system call might
be left alone.  Of course, that will be the least of our worries if we
really ever need to care, so this may not be worth really caring about.

[ Fixed for lost 'loff_t' cast noticed by Andrew Morton ]

Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ralf Baechle <ralf@linux-mips.org>>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-04 14:20:34 -07:00
..
9p vfs: simple_set_mnt() should return void 2009-03-27 14:44:03 -04:00
adfs fs/adfs: return f_fsid for statfs(2) 2009-04-02 19:05:08 -07:00
affs fs/affs: return f_fsid for statfs(2) 2009-04-02 19:05:08 -07:00
afs FS-Cache: Make kAFS use FS-Cache 2009-04-03 16:42:41 +01:00
autofs constify dentry_operations: autofs, autofs4 2009-03-27 14:44:00 -04:00
autofs4 autofs4: fix lookup deadlock 2009-04-01 08:59:23 -07:00
befs fs/befs: return f_fsid for statfs(2) 2009-04-02 19:05:08 -07:00
bfs fs/Kconfig: move bfs out 2009-01-22 13:15:57 +03:00
btrfs Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2009-04-03 15:14:44 -07:00
cachefiles CacheFiles: A cache that backs onto a mounted filesystem 2009-04-03 16:42:41 +01:00
cifs New helper - current_umask() 2009-03-31 23:00:26 -04:00
coda constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
configfs constify dentry_operations: configfs 2009-03-27 14:44:03 -04:00
cramfs fs/cramfs: return f_fsid for statfs(2) 2009-04-02 19:05:08 -07:00
debugfs debugfs: add helpers for exporting a size_t simple value 2009-01-07 10:00:16 -08:00
devpts Merge code for single and multiple-instance mounts 2009-03-27 14:44:04 -04:00
dlm dlm: fix length calculation in compat code 2009-03-11 12:23:59 -05:00
ecryptfs ecryptfs: use kzfree() 2009-04-01 08:59:23 -07:00
efs fs/efs: return f_fsid for statfs(2) 2009-04-02 19:05:09 -07:00
exofs exofs: Documentation 2009-03-31 19:44:38 +03:00
exportfs Merge branch 'next' into for-linus 2008-12-25 11:40:09 +11:00
ext2 New helper - current_umask() 2009-03-31 23:00:26 -04:00
ext3 Merge branch 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-04-03 11:10:33 -07:00
ext4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-04-03 15:24:35 -07:00
fat Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
freevxfs fs/Kconfig: move vxfs out 2009-01-22 13:15:58 +03:00
fscache FS-Cache: Implement data I/O part of netfs API 2009-04-03 16:42:39 +01:00
fuse fuse: allow private mappings of "direct_io" files 2009-04-02 14:25:35 +02:00
gfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
hfs fs/hfs: return f_fsid for statfs(2) 2009-04-02 19:05:09 -07:00
hfsplus Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
hostfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
hpfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
hppfs hppfs: hppfs_read_file() may return -ERROR 2009-04-02 19:04:53 -07:00
hugetlbfs mm: reintroduce and deprecate rlimit based access for SHM_HUGETLB 2009-04-01 08:59:12 -07:00
isofs fs/isofs: return f_fsid for statfs(2) 2009-04-02 19:05:09 -07:00
jbd Merge branch 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-04-03 11:10:33 -07:00
jbd2 jbd2: Update locking coments 2009-03-27 17:20:40 -04:00
jffs2 New helper - current_umask() 2009-03-31 23:00:26 -04:00
jfs New helper - current_umask() 2009-03-31 23:00:26 -04:00
lockd NSM: Fix unaligned accesses in nsm_init_private() 2009-04-01 13:24:14 -04:00
minix fs/minix: return f_fsid for statfs(2) 2009-04-02 19:05:09 -07:00
ncpfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
nfs NFS: Add mount options to enable local caching on NFS 2009-04-03 16:42:48 +01:00
nfs_common SUNRPC: nfsacl_encode/nfsacl_decode should be exported as GPL-only 2008-12-23 15:21:32 -05:00
nfsd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
nls
notify fs: avoid I_NEW inodes 2009-03-27 14:44:05 -04:00
ntfs ntfs: remove private wrapper of endian helpers 2009-04-01 08:59:18 -07:00
ocfs2 ocfs2: recover orphans in offline slots during recovery and mount 2009-04-03 11:39:26 -07:00
omfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
openpromfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
partitions Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6 2009-03-26 16:04:22 -07:00
proc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-04-03 15:24:35 -07:00
qnx4 fs/qnx4: return f_fsid for statfs(2) 2009-04-02 19:05:10 -07:00
quota vfs: skip I_CLEAR state inodes 2009-04-02 19:04:48 -07:00
ramfs ramfs: add support for "mode=" mount option 2009-04-01 08:59:22 -07:00
reiserfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-04-02 21:09:10 -07:00
romfs fs/Kconfig: move romfs out 2009-01-22 13:15:59 +03:00
smbfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
squashfs fs/squashfs: return f_fsid for statfs(2) 2009-04-02 19:05:10 -07:00
sysfs mm: page_mkwrite change prototype to match fault: fix sysfs 2009-04-01 08:59:14 -07:00
sysv fs/sysv: return f_fsid for statfs(2) 2009-04-02 19:05:10 -07:00
ubifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-04-03 15:24:35 -07:00
udf udf: Don't write integrity descriptor too often 2009-04-02 13:36:28 +02:00
ufs fs/ufs: return f_fsid for statfs(2) 2009-04-02 19:05:10 -07:00
xfs Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfs 2009-04-03 09:52:29 -07:00
aio.c aio: lookup_ioctx can return the wrong value when looking up a bogus context 2009-03-19 15:57:18 -07:00
anon_inodes.c constify dentry_operations: rest 2009-03-27 14:44:03 -04:00
attr.c vfs: Use lowercase names of quota functions 2009-03-26 02:18:35 +01:00
bad_inode.c kill ->dir_notify() 2008-12-31 18:07:43 -05:00
binfmt_aout.c sanitize ifdefs in binfmt_aout 2009-01-03 11:45:54 -08:00
binfmt_elf.c Trim includes in binfmt_elf 2009-03-31 23:00:27 -04:00
binfmt_elf_fdpic.c bin_elf_fdpic: check the return value of clear_user 2009-04-02 19:05:01 -07:00
binfmt_em86.c
binfmt_flat.c FLAT: Don't attempt to expand the userspace stack to fill the space allocated 2009-01-08 12:04:47 +00:00
binfmt_misc.c fs/binfmt_misc.c: add terminating newline to /proc/sys/fs/binfmt_misc/status 2009-01-06 15:59:19 -08:00
binfmt_script.c
binfmt_som.c Don't crap into descriptor table in binfmt_som 2009-03-31 23:00:28 -04:00
bio-integrity.c block: add private bio_set for bio integrity allocations 2009-03-24 12:35:17 +01:00
bio.c trivial: Fix typo in bio_split()'s documentation 2009-03-30 15:22:02 +02:00
block_dev.c Cleanup after commit 585d3bc06f 2009-04-01 07:07:16 -04:00
buffer.c Merge branch 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-04-03 11:10:33 -07:00
char_dev.c fs: fix name overwrite in __register_chrdev_region() 2009-01-06 15:59:13 -08:00
compat.c Make non-compat preadv/pwritev use native register size 2009-04-04 14:20:34 -07:00
compat_binfmt_elf.c
compat_ioctl.c Merge branch 'for-linus' of git://neil.brown.name/md 2009-04-03 09:08:19 -07:00
dcache.c Trim includes of fdtable.h 2009-03-31 23:00:28 -04:00
dcookies.c [CVE-2009-0029] System call wrapper special cases 2009-01-14 14:15:18 +01:00
direct-io.c fs: truncate blocks outside i_size after O_DIRECT write error 2009-01-06 15:59:06 -08:00
drop_caches.c vfs: skip I_CLEAR state inodes 2009-04-02 19:04:48 -07:00
eventfd.c epoll keyed wakeups: make eventfd use keyed wakeups 2009-04-01 08:59:20 -07:00
eventpoll.c epoll keyed wakeups: teach epoll about hints coming with the wakeup key 2009-04-01 08:59:20 -07:00
exec.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
fcntl.c Fix a lockdep warning in fasync_helper() 2009-03-30 08:00:24 -06:00
fifo.c [PATCH] introduce fmode_t, do annotations 2008-10-21 07:47:06 -04:00
file.c
file_table.c trivial: remove unused variable 'path' in alloc_file() 2009-03-30 15:22:03 +02:00
filesystems.c [CVE-2009-0029] System call wrappers part 27 2009-01-14 14:15:29 +01:00
fs-writeback.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-04-03 15:24:35 -07:00
fs_struct.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
generic_acl.c New helper - current_umask() 2009-03-31 23:00:26 -04:00
inode.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
internal.h New locking/refcounting for fs_struct 2009-03-31 23:00:26 -04:00
ioctl.c Rationalize fasync return values 2009-03-16 08:34:35 -06:00
ioprio.c [CVE-2009-0029] System call wrappers part 28 2009-01-14 14:15:30 +01:00
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache 2009-04-03 10:07:43 -07:00
Kconfig.binfmt CORE_DUMP_DEFAULT_ELF_HEADERS depends on ELF_CORE 2009-01-09 16:54:41 -08:00
libfs.c vfs: simple_set_mnt() should return void 2009-03-27 14:44:03 -04:00
locks.c [CVE-2009-0029] System call wrappers part 16 2009-01-14 14:15:25 +01:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache 2009-04-03 10:07:43 -07:00
mbcache.c
mpage.c Remove two unneeded exports and make two symbols static in fs/mpage.c 2009-04-01 07:38:54 -04:00
namei.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
namespace.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
nfsctl.c [CVE-2009-0029] System call wrappers part 27 2009-01-14 14:15:29 +01:00
no-block.c
open.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
pipe.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
pnode.c
pnode.h
posix_acl.c CRED: Wrap task credential accesses in the filesystem subsystem 2008-11-14 10:39:05 +11:00
read_write.c Make non-compat preadv/pwritev use native register size 2009-04-04 14:20:34 -07:00
read_write.h
readdir.c [CVE-2009-0029] System call wrappers part 32 2009-01-14 14:15:31 +01:00
select.c [CVE-2009-0029] System call wrappers part 32 2009-01-14 14:15:31 +01:00
seq_file.c cpumask: fix seq_bitmap_*() functions. 2009-03-30 22:05:11 +10:30
signalfd.c [CVE-2009-0029] System call wrappers part 31 2009-01-14 14:15:31 +01:00
splice.c FS-Cache: Recruit a page flags for cache management 2009-04-03 16:42:36 +01:00
stack.c
stat.c [CVE-2009-0029] System call wrappers part 30 2009-01-14 14:15:30 +01:00
super.c CacheFiles: Export things for CacheFiles 2009-04-03 16:42:40 +01:00
sync.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-quota-2.6 2009-03-27 14:48:34 -07:00
timerfd.c timerfd: add flags check 2009-02-18 15:37:53 -08:00
utimes.c [CVE-2009-0029] System call wrappers part 30 2009-01-14 14:15:30 +01:00
xattr.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
xattr_acl.c