[RFC] Non-executable stack on SPARC

Mark Kettenis
2004-01-25T23:50:16Z

A while ago, I established that getting inferior function calls on
SPARC working with a non-executable stack is remarkably simple. Just
acknowledging that breakpoint instructions may cause SIGSEGV, as per
the attached patch, is enough. However, some people were afraid that
blindly applying this patch might cause some problems on other
targets. I think there are two alternatives:

1. Only check for SIGSEGV if the target in question uses "ON_STACK"
for its call_dummy_location.

2. Add a new method to the architecture vector to check whether a
particular signal may have been the result of a breakpoint
instruction. Suggested name & signature:

int breakpoint_signal_p (struct gdbarch *gdbarch, int signal)

Preferences?

I'd like to get this sorted before 6.1, since OpenBSD/sparc has a
non-executable stack, and some people are running SPARC Solaris with a
non-executable stack too.

Mark

Index: infrun.c
===================================================================
RCS file: /cvs/src/src/gdb/infrun.c,v
retrieving revision 1.122
diff -u -p -r1.122 infrun.c
--- infrun.c 25 Nov 2003 16:01:36 -0000 1.122
+++ infrun.c 25 Jan 2004 23:37:01 -0000
@@ -1864,6 +1864,7 @@ handle_inferior_event (struct execution_
if (stop_signal == TARGET_SIGNAL_TRAP
|| (breakpoints_inserted &&
(stop_signal == TARGET_SIGNAL_ILL
+ || stop_signal == TARGET_SIGNAL_SEGV
|| stop_signal == TARGET_SIGNAL_EMT))
|| stop_soon == STOP_QUIETLY
|| stop_soon == STOP_QUIETLY_NO_SIGSTOP)