From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sun, 4 Jan 2026 20:40:35 +0000 (+0100)
Subject: hurd: check that signal processing does not hurt the x86_64 redzone
X-Git-Tag: glibc-2.43~49
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d942f309e3a93dd35c607fe41009f4357ba1d482;p=thirdparty%2Fglibc.git

hurd: check that signal processing does not hurt the x86_64 redzone
---

diff --git a/sysdeps/mach/hurd/x86_64/Makefile b/sysdeps/mach/hurd/x86_64/Makefile
index 2b43f5d625..270705ac66 100644
--- a/sysdeps/mach/hurd/x86_64/Makefile
+++ b/sysdeps/mach/hurd/x86_64/Makefile
@@ -4,6 +4,11 @@ ifeq ($(subdir),conform)
 conformtest-xfail-conds += x86_64-gnu
 endif
 
+ifeq ($(subdir),hurd)
+tests += tst-sig-redzone
+$(objpfx)tst-sig-redzone: $(shared-thread-library)
+endif
+
 ifeq ($(subdir),stdlib)
 sysdep_routines += __start_context
 endif
diff --git a/sysdeps/mach/hurd/x86_64/tst-sig-redzone.c b/sysdeps/mach/hurd/x86_64/tst-sig-redzone.c
new file mode 100644
index 0000000000..0855bd6900
--- /dev/null
+++ b/sysdeps/mach/hurd/x86_64/tst-sig-redzone.c
@@ -0,0 +1,109 @@
+/* Test the redzone is not affected during signal handling.
+
+   Copyright (C) 2026 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+
+#include <assert.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdatomic.h>
+
+#include <mach/message.h>
+#include <mach/gnumach.h>
+#include <mach/mach_traps.h>
+#include <mach-shortcuts.h>
+#include <mach_init.h>
+#include <hurd/io.h>
+#include <hurd/io_reply.h>
+
+#include <support/check.h>
+#include <support/xthread.h>
+
+static volatile atomic_bool startflag = ATOMIC_VAR_INIT (false);
+static volatile atomic_bool loopflag = ATOMIC_VAR_INIT (true);
+
+void handler (int signum, siginfo_t *info, void *context)
+{
+  char buf[128];
+  memset (buf, 0x77, sizeof buf);
+  printf ("signal %d hurting stack a bit\n", signum);
+  atomic_store_explicit (&loopflag, false, memory_order_release);
+}
+
+/* Helper thread to send a signal to the main thread  */
+void* signal_sender (void *arg)
+{
+  sigset_t ss;
+  assert (! sigemptyset (&ss));
+  assert (! sigaddset (&ss, SIGUSR1));
+  assert (! sigprocmask (SIG_BLOCK, &ss, NULL));
+
+  while (!atomic_load_explicit (&startflag, memory_order_acquire))
+    ;
+  TEST_COMPARE (kill (getpid (), SIGUSR1), 0);
+
+  return NULL;
+}
+
+static int do_test (void)
+{
+  struct sigaction act = { 0 };
+  act.sa_sigaction = &handler;
+  TEST_COMPARE (sigaction (SIGUSR1, &act, NULL), 0);
+
+  pthread_t thsender = xpthread_create (NULL, signal_sender, NULL);
+
+  int check_redzone (void);
+  TEST_COMPARE (check_redzone (), 0);
+
+  xpthread_join (thsender);
+  return EXIT_SUCCESS;
+}
+
+asm (
+"check_redzone:\n"
+
+"	movabs	$0x3333333333333333, %rax\n"
+"	mov	$(128/8), %ecx\n"
+"	lea	-128(%rsp), %rdi\n"
+"rep	stosq\n"
+
+"	movl	$1, startflag(%rip)\n"
+"wait:\n"
+"	cmpl	$0, loopflag(%rip)\n"
+"	jne	wait\n"
+
+"	movabs	$0x3333333333333333, %rax\n"
+"	mov	$(128/8), %ecx\n"
+"	lea	-128(%rsp), %rdi\n"
+"repe	scasq\n"
+"	jne	fail\n"
+
+"	xor	%rax,%rax\n"
+"	ret\n"
+"fail:\n"
+"	movq	$1,%rax\n"
+"	ret\n"
+);
+
+#include <support/test-driver.c>