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 0a489cb3b6a7b277030cdbc97c2c65905db94536.
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>
diff --git a/fs/open.c b/fs/open.c
index 8279c65..53ec28c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -332,6 +332,7 @@
asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
{
long ret = do_sys_ftruncate(fd, length, 1);
+ /* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
}
@@ -346,6 +347,7 @@
asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
{
long ret = do_sys_ftruncate(fd, length, 0);
+ /* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
}
@@ -1097,20 +1099,30 @@
asmlinkage long sys_open(const char __user *filename, int flags, int mode)
{
+ long ret;
+
if (force_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);
asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
int mode)
{
+ long ret;
+
if (force_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);