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x86: be careful about tailcall breakage for sys_open[at] too 

Came up through a quick grep for other cases similar to the ftruncate()
one in commit 0a489cb3b6.

Also, add a comment, so that people who read the code understand why we
do what looks like a no-op.

(Again, this won't actually matter to any sane user, since libc will
save and restore the register gcc stomps on, but it's still wrong to
stomp on it)

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Linus Torvalds 2006-04-18 13:22:59 -07:00
parent 0a489cb3b6
commit 385910f2b2
1 changed files with 14 additions and 2 deletions
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16
fs/open.c
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@ -332,6 +332,7 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length) asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
{ {
long ret = do_sys_ftruncate(fd, length, 1); long ret = do_sys_ftruncate(fd, length, 1);
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret); prevent_tail_call(ret);
return ret; return ret;
} }
@ -346,6 +347,7 @@ asmlinkage long sys_truncate64(const char __user * path, loff_t length)
asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length) asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
{ {
long ret = do_sys_ftruncate(fd, length, 0); long ret = do_sys_ftruncate(fd, length, 0);
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret); prevent_tail_call(ret);
return ret; return ret;
} }
@ -1097,20 +1099,30 @@ long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
asmlinkage long sys_open(const char __user *filename, int flags, int mode) asmlinkage long sys_open(const char __user *filename, int flags, int mode)
{ {
long ret;
if (force_o_largefile()) if (force_o_largefile())
flags |= O_LARGEFILE; flags |= O_LARGEFILE;
return do_sys_open(AT_FDCWD, filename, flags, mode); ret = do_sys_open(AT_FDCWD, filename, flags, mode);
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
} }
EXPORT_SYMBOL_GPL(sys_open); EXPORT_SYMBOL_GPL(sys_open);
asmlinkage long sys_openat(int dfd, const char __user *filename, int flags, asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
int mode) int mode)
{ {
long ret;
if (force_o_largefile()) if (force_o_largefile())
flags |= O_LARGEFILE; flags |= O_LARGEFILE;
return do_sys_open(dfd, filename, flags, mode); ret = do_sys_open(dfd, filename, flags, mode);
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
} }
EXPORT_SYMBOL_GPL(sys_openat); EXPORT_SYMBOL_GPL(sys_openat);