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From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Subject: [PATCH] Fix SS_ONSTACK support
* sysdeps/mach/hurd/i386/sigreturn.c (__sigreturn2): New function,
unlocks SS and returns to the saved PC.
(__sigreturn): Do not unlock SS, and "return" into __sigreturn2 on the
thread stack instead of the saved PC.
---
sysdeps/mach/hurd/i386/sigreturn.c | 68 +++++++++++++++++++++++---------------
1 file changed, 42 insertions(+), 26 deletions(-)
diff --git a/sysdeps/mach/hurd/i386/sigreturn.c b/sysdeps/mach/hurd/i386/sigreturn.c
index 83c0246..204bd47 100644
--- a/sysdeps/mach/hurd/i386/sigreturn.c
+++ b/sysdeps/mach/hurd/i386/sigreturn.c
@@ -24,6 +24,36 @@ register int *sp asm ("%esp");
#include <stdlib.h>
#include <string.h>
+/* This is run on the thread stack after restoring it, to be able to
+ unlock SS off sigstack. */
+static void
+__sigreturn2 (int *usp)
+{
+ struct hurd_sigstate *ss = _hurd_self_sigstate ();
+ _hurd_sigstate_unlock (ss);
+
+ sp = usp;
+#define A(line) asm volatile (#line)
+ /* The members in the sigcontext are arranged in this order
+ so we can pop them easily. */
+
+ /* Pop the segment registers (except %cs and %ss, done last). */
+ A (popl %gs);
+ A (popl %fs);
+ A (popl %es);
+ A (popl %ds);
+ /* Pop the general registers. */
+ A (popa);
+ /* Pop the processor flags. */
+ A (popf);
+ /* Return to the saved PC. */
+ A (ret);
+
+ /* Firewall. */
+ A (hlt);
+#undef A
+}
+
int
__sigreturn (struct sigcontext *scp)
{
@@ -67,13 +97,7 @@ __sigreturn (struct sigcontext *scp)
}
if (scp->sc_onstack)
- {
- ss->sigaltstack.ss_flags &= ~SS_ONSTACK;
- /* XXX cannot unlock until off sigstack */
- abort ();
- }
- else
- _hurd_sigstate_unlock (ss);
+ ss->sigaltstack.ss_flags &= ~SS_ONSTACK;
/* Destroy the MiG reply port used by the signal handler, and restore the
reply port in use by the thread when interrupted. */
@@ -108,27 +132,19 @@ __sigreturn (struct sigcontext *scp)
*--usp = scp->sc_efl;
memcpy (usp -= 12, &scp->sc_i386_thread_state, 12 * sizeof (int));
- sp = usp;
-
-#define A(line) asm volatile (#line)
- /* The members in the sigcontext are arranged in this order
- so we can pop them easily. */
-
- /* Pop the segment registers (except %cs and %ss, done last). */
- A (popl %gs);
- A (popl %fs);
- A (popl %es);
- A (popl %ds);
- /* Pop the general registers. */
- A (popa);
- /* Pop the processor flags. */
- A (popf);
- /* Return to the saved PC. */
- A (ret);
+ /* Pass usp to __sigreturn2 so it can unwind itself easily. */
+ *(usp-1) = (int) usp;
+ --usp;
+ /* Bogus return address for __sigreturn2 */
+ *--usp = 0;
+ *--usp = (int) __sigreturn2;
+ /* Restore thread stack */
+ sp = usp;
+ /* Return into __sigreturn2. */
+ asm volatile ("ret");
/* Firewall. */
- A (hlt);
-#undef A
+ asm volatile ("hlt");
}
/* NOTREACHED */
--
tg: (ab44f81..) t/ONSTACK (depends on: t/tls-threadvar t/hurdsig-global-dispositions)
|
