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SubjectRe: + fully-honor-vdso_enabled.patch added to -mm tree
On Sat, Mar 03, 2007 at 01:18:54AM +0300, Oleg Nesterov wrote:
> On 03/02, John Reiser wrote:
> > Paul Mundt has commented on setup_rt_frame() and provided a patch which
> > bullet-proofs that area. I will include that patch into the next revision.
>
> Confused. I still think his patch incomplete. Don't we need the same check
> in setup_rt_frame() ?
>
Yes, you're right. The patch is missing the proper restorer logic in the
setup_rt_frame() case. This should handle both of them, restoring the
previous logic when the VDSO is disabled.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

--

arch/i386/kernel/signal.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
index 4f99e87..26c2497 100644
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -350,7 +350,7 @@ static int setup_frame(int sig, struct k_sigaction *ka,
goto give_sigsegv;
}

- if (current->binfmt->hasvdso)
+ if (current->binfmt->hasvdso && current->mm->context.vdso)
restorer = (void *)VDSO_SYM(&__kernel_sigreturn);
else
restorer = (void *)&frame->retcode;
@@ -449,17 +449,20 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
goto give_sigsegv;

/* Set up to return from userspace. */
- restorer = (void *)VDSO_SYM(&__kernel_rt_sigreturn);
+ if (current->binfmt->hasvdso && current->mm->context.vdso)
+ restorer = (void *)VDSO_SYM(&__kernel_rt_sigreturn);
+ else
+ restorer = (void *)&frame->retcode;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
err |= __put_user(restorer, &frame->pretcode);
-
+
/*
* This is movl $,%eax ; int $0x80
*
- * WE DO NOT USE IT ANY MORE! It's only left here for historical
- * reasons and because gdb uses it as a signature to notice
- * signal handler stack frames.
+ * This is not used in the general case! It's left here for
+ * handling toggling of the VDSO state and because gdb uses it
+ * as a signature to notice signal handler stack frames.
*/
err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
-
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