From: Bruno Haible <bruno@clisp.org>
Date: Sun, 7 Apr 2024 14:53:02 +0000 (+0200)
Subject: sigsegv tests: Avoid a crash on NetBSD 10.0/i386.
X-Git-Tag: v1.0~151
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=95f52c5d1bb5499e695b2e77a6385bdff4e7c46b;p=thirdparty%2Fgnulib.git

sigsegv tests: Avoid a crash on NetBSD 10.0/i386.

* tests/test-sigsegv-catch-stackoverflow1.c
(stackoverflow_handler_continuation): On NetBSD/i386, align the stack
pointer before calling longjmp.
---

diff --git a/ChangeLog b/ChangeLog
index e6c2b5cd20..e9054029a7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2024-04-07  Bruno Haible  <bruno@clisp.org>
+
+	sigsegv tests: Avoid a crash on NetBSD 10.0/i386.
+	* tests/test-sigsegv-catch-stackoverflow1.c
+	(stackoverflow_handler_continuation): On NetBSD/i386, align the stack
+	pointer before calling longjmp.
+
 2024-04-07  Bruno Haible  <bruno@clisp.org>
 
 	gnulib-tool.py: Add comment.
diff --git a/tests/test-sigsegv-catch-stackoverflow1.c b/tests/test-sigsegv-catch-stackoverflow1.c
index 20915adfd5..46b120686c 100644
--- a/tests/test-sigsegv-catch-stackoverflow1.c
+++ b/tests/test-sigsegv-catch-stackoverflow1.c
@@ -55,7 +55,26 @@ static volatile char *stack_upper_bound;
 static void
 stackoverflow_handler_continuation (void *arg1, void *arg2, void *arg3)
 {
+#if defined __NetBSD__ && defined __i386__
+  /* On NetBSD 10.0/i386, when built as part of a testdir-all (but not as part
+     of a testdir for just the module 'sigsegv'!) this program crashes.  The
+     cause is that:
+       - The alternate stack is not aligned (which is intentional, see
+         altstack-util.h) and NetBSD does not align the stack pointer while
+         switching to the alternate stack.
+       - When %esp is not aligned, the dynamic linker crashes in function
+         _rtld_bind while resolving the symbol 'longjmp'.
+     We would around this by aligning the stack pointer, to a multiple of 8.  */
+  int *argp;
+  __asm__ __volatile__ ("movl %1,%0" : "=r" (argp) : "r" (&arg1));
+  unsigned long sp;
+  __asm__ __volatile__ ("movl %%esp,%0" : "=r" (sp));
+  sp &= ~7UL;
+  __asm__ __volatile__ ("movl %0,%%esp" : : "r" (sp));
+  int arg = *argp;
+#else
   int arg = (int) (long) arg1;
+#endif
   longjmp (mainloop, arg);
 }