selftests/harness: remove use of LINE_MAX

Android was seeing a compliation error because its C library does not
define LINE_MAX.  This replaces the use of LINE_MAX / snprintf with
asprintf, which will change the behavior to not truncate the test name if
it is over 2048 chars long.

See also:
https://github.com/llvm/llvm-project/issues/88119

[akpm@linux-foundation.org: remove limits.h include, per Edward]
[akpm@linux-foundation.org: check asprintf() return]
[usama.anjum@collabora.com: fix undeclared function error]
  Link: https://lkml.kernel.org/r/20240417075530.3807625-1-usama.anjum@collabora.com
Link: https://lkml.kernel.org/r/20240411231954.62156-1-edliaw@google.com
Fixes: 38c957f0 ("selftests: kselftest_harness: generate test name once")
Signed-off-by: Edward Liaw <edliaw@google.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Bill Wendling <morbo@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Edward Liaw <edliaw@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/kselftest_harness.h

@@ -56,7 +56,6 @@
 #include <asm/types.h>
 #include <ctype.h>
 #include <errno.h>
-#include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -1156,7 +1155,7 @@ void __run_test(struct __fixture_metadata *f,
 		struct __test_metadata *t)
 {
 	struct __test_xfail *xfail;
-	char test_name[LINE_MAX];
+	char *test_name;
 	const char *diagnostic;
 
 	/* reset test struct */
@@ -1164,8 +1163,12 @@ void __run_test(struct __fixture_metadata *f,
 	t->trigger = 0;
 	memset(t->results->reason, 0, sizeof(t->results->reason));
 
-	snprintf(test_name, sizeof(test_name), "%s%s%s.%s",
-		 f->name, variant->name[0] ? "." : "", variant->name, t->name);
+	if (asprintf(&test_name, "%s%s%s.%s", f->name,
+		variant->name[0] ? "." : "", variant->name, t->name) == -1) {
+		ksft_print_msg("ERROR ALLOCATING MEMORY\n");
+		t->exit_code = KSFT_FAIL;
+		_exit(t->exit_code);
+	}
 
 	ksft_print_msg(" RUN           %s ...\n", test_name);
 
@@ -1203,6 +1206,7 @@ void __run_test(struct __fixture_metadata *f,
 
 	ksft_test_result_code(t->exit_code, test_name,
 			      diagnostic ? "%s" : "", diagnostic);
+	free(test_name);
 }
 
 static int test_harness_run(int argc, char **argv)

tools/testing/selftests/mm/mdwe_test.c

@@ -7,6 +7,7 @@
 #include <linux/mman.h>
 #include <linux/prctl.h>
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/auxv.h>