lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[PATCH] uml skas0: stop gcc's insanity

Browse Source 
With Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>

UML skas0 stub has been miscompiling for many people (incidentally not
the authors), depending on the used GCC versions.

I think (and testing on some GCC versions shows) this patch avoids the
fundamental issue which is behind this, namely gcc using the stack when
we have just replaced it, behind gcc's back.  The remapping and storage
of the return value is hidden in a blob of asm, hopefully giving gcc no
room for creativity.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Dike
2005-12-18 17:50:39 +01:00
committed by Linus Torvalds
parent 76c842d8f8
commit 5b7b15afee
3 changed files with 48 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
arch/um/kernel/skas/clone.c
View File

@@ -18,11 +18,10 @@
* on some systems.
*/
#define STUB_DATA(field) (((struct stub_data *) UML_CONFIG_STUB_DATA)->field)
void __attribute__ ((__section__ (".__syscall_stub")))
stub_clone_handler(void)
{
struct stub_data *data = (struct stub_data *) UML_CONFIG_STUB_DATA;
long err;
err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
@@ -35,17 +34,21 @@ stub_clone_handler(void)
if(err)
goto out;
err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
(long) &STUB_DATA(timer), 0);
err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
(long) &data->timer, 0);
if(err)
goto out;
err = stub_syscall6(STUB_MMAP_NR, UML_CONFIG_STUB_DATA,
UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, STUB_DATA(fd),
STUB_DATA(offset));
remap_stack(data->fd, data->offset);
goto done;
out:
/* save current result. Parent: pid; child: retcode of mmap */
STUB_DATA(err) = err;
/* save current result.
* Parent: pid;
* child: retcode of mmap already saved and it jumps around this
* assignment
*/
data->err = err;
done:
trap_myself();
}