tests: check decoding of SEGV_ACCERR

* tests/segv_accerr.c: New file.
* tests/gen_tests.in (segv_accerr): New test.
* tests/Makefile.am (check_PROGRAMS): Add segv_accerr.
* tests/.gitignore: Likewise.

tests/.gitignore

@@ -860,6 +860,7 @@ seccomp_get_action_avail
 seccomp_get_notif_sizes
 seccomp_get_notif_sizes-success
 secontext.am
+segv_accerr
 segv_pkuerr
 select
 select-P

tests/Makefile.am

@@ -335,6 +335,7 @@ check_PROGRAMS = $(PURE_EXECUTABLES) \
 	seccomp-filter-v \
 	seccomp-strict \
 	seccomp_get_notif_sizes-success \
+	segv_accerr \
 	segv_pkuerr \
 	select-P \
 	set_ptracer_any \

tests/gen_tests.in

@@ -840,6 +840,7 @@ seccomp-filter-v	-v -e trace=seccomp
 seccomp_get_action_avail	-e trace=seccomp
 seccomp_get_notif_sizes		-etrace=seccomp -a42
 seccomp_get_notif_sizes-success	-einject=seccomp:retval=42 -etrace=seccomp -a42
+segv_accerr	-qq --trace=none
 segv_pkuerr	-qq --trace=none
 select	-a36
 select-P	-a36 -e trace=select -P /dev/full 9>>/dev/full

tests/segv_accerr.c

@@ -0,0 +1,54 @@
+/*
+ * Check decoding of SEGV_ACCERR.
+ *
+ * Copyright (c) 2022 Dmitry V. Levin <ldv@strace.io>
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "tests.h"
+#include <signal.h>
+
+#ifdef SEGV_ACCERR
+
+# include <stdio.h>
+# include <stdlib.h>
+# include <unistd.h>
+# include <sys/mman.h>
+
+static void
+handler(int sig)
+{
+	_exit(0);
+}
+
+int
+main(void) {
+	int *p = mmap(NULL, get_page_size(), PROT_NONE,
+		      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (p == MAP_FAILED)
+		perror_msg_and_fail("mmap");
+
+	const struct sigaction act = {
+		.sa_handler = handler,
+		.sa_flags = SA_RESETHAND
+	};
+	if (sigaction(SIGSEGV, &act, NULL))
+		perror_msg_and_fail("sigaction");
+
+	printf("--- SIGSEGV {si_signo=SIGSEGV"
+	       ", si_code=SEGV_ACCERR, si_addr=%p} ---\n", p);
+	fflush(stdout);
+
+	if (*p)
+		__asm__ volatile("":::"memory");
+
+	error_msg_and_skip("PROT_NONE page is readable");
+}
+
+#else
+
+SKIP_MAIN_UNDEFINED("SEGV_ACCERR")
+
+#endif