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[commit] Update OpenBSD/sparc64 signal trampoline detection
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: gdb-patches at sourceware dot org
- Date: Tue, 9 Aug 2005 21:38:00 +0200 (CEST)
- Subject: [commit] Update OpenBSD/sparc64 signal trampoline detection
OpenBSD 3.8 will have a somewhat different signal trampoline. This
patch makes sure we properly detect it.
Mark
Index: ChangeLog
from Mark Kettenis <kettenis@gnu.org>
* sparc64obsd-tdep.c: Tweak comments.
(sparc64obsd_sigreturn_offset): Add offset for new OpenBSD 3.8
signal trampoline.
Index: sparc64obsd-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/sparc64obsd-tdep.c,v
retrieving revision 1.14
diff -u -p -r1.14 sparc64obsd-tdep.c
--- sparc64obsd-tdep.c 12 Jun 2005 11:10:56 -0000 1.14
+++ sparc64obsd-tdep.c 9 Aug 2005 19:31:12 -0000
@@ -68,19 +68,27 @@ sparc64obsd_supply_gregset (const struct
/* Signal trampolines. */
-/* The OpenBSD kernel maps the signal trampoline at some random
- location in user space, which means that the traditional BSD way of
- detecting it won't work.
-
- The signal trampoline will be mapped at an address that is page
- aligned. We recognize the signal trampoline by the looking for the
- sigreturn system call. The offset where we can find the code that
- makes this system call varies from release to release. For OpenBSD
- 3.6 and later releases we can find the code at offset 0xec. For
- OpenBSD 3.5 and earlier releases, we find it at offset 0xe8. */
+/* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page
+ in virtual memory. The randomness makes it somewhat tricky to
+ detect it, but fortunately we can rely on the fact that the start
+ of the sigtramp routine is page-aligned. We recognize the
+ trampoline by looking for the code that invokes the sigreturn
+ system call. The offset where we can find that code varies from
+ release to release.
+ By the way, the mapping mentioned above is read-only, so you cannot
+ place a breakpoint in the signal trampoline. */
+
+/* Default page size. */
static const int sparc64obsd_page_size = 8192;
-static const int sparc64obsd_sigreturn_offset[] = { 0xec, 0xe8, -1 };
+
+/* Offset for sigreturn(2). */
+static const int sparc64obsd_sigreturn_offset[] = {
+ 0xf0, /* OpenBSD 3.8 */
+ 0xec, /* OpenBSD 3.6 */
+ 0xe8, /* OpenBSD 3.2 */
+ -1
+};
static int
sparc64obsd_pc_in_sigtramp (CORE_ADDR pc, char *name)