[RFC PATCH 4/6] selftests: fix build errors on alpine linux

[Hajime Tazaki <thehajime@gmail.com>]

Some nommu architectures only work on Alpine Linux, which doesn't use
glibc for the standard library.  It uses musl-libc and is implemented in
a different way as glibc, resulting build failures.

This commit fixes this issue by adding missing definitions. The fixes
are now only covered to TARGETS=mm which was tested for the moment;
future contributions are needed to fully build/execute tests on nommu
platforms.

Cc: Shuah Khan <shuah@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Liam R. Howlett" <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-kselftest@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-um@lists.infradead.org
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
 tools/testing/selftests/kselftest.h      | 43 ++++++++++++++++++++++++
 tools/testing/selftests/lib.mk           |  2 +-
 tools/testing/selftests/mm/hugetlb_dio.c |  8 ++---
 tools/testing/selftests/mm/mdwe_test.c   |  4 +--
 4 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h
index ae18c491ae53..ac21bf3d802e 100644
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -58,6 +58,7 @@
 #include <string.h>
 #include <stdio.h>
 #include <sys/utsname.h>
+#include <stdint.h>
 #endif
 
 #ifndef ARRAY_SIZE
@@ -81,6 +82,48 @@
 #endif
 #endif /* end arch */
 
+#if !defined(NOLIBC) && !defined(__GLIBC__)
+#ifdef __LP64__
+typedef int64_t __fsword_t;
+#else
+typedef int32_t __fsword_t;
+#endif
+
+/*
+ * for a workaround to avoid struct conflict under
+ * musl-libc (<sys/prctl.h> v.s. <linux/prctl.h>)
+ */
+#include <sys/prctl.h>
+#ifndef _LINUX_PRCTL_H
+#define _LINUX_PRCTL_H
+#endif
+
+#ifndef PR_SET_MDWE
+#define PR_SET_MDWE 65
+#endif
+
+#ifndef PR_MDWE_REFUSE_EXEC_GAIN
+#define PR_MDWE_REFUSE_EXEC_GAIN (1UL << 0)
+#endif
+
+#ifndef PR_MDWE_NO_INHERIT
+#define PR_MDWE_NO_INHERIT (1UL << 1)
+#endif
+
+#ifndef PR_GET_MDWE
+#define PR_GET_MDWE 66
+#endif
+
+#ifndef PR_SET_MEMORY_MERGE
+#define PR_SET_MEMORY_MERGE 67
+#endif
+
+#ifndef PR_GET_MEMORY_MERGE
+#define PR_GET_MEMORY_MERGE 68
+#endif
+
+#endif
+
 /* define kselftest exit codes */
 #define KSFT_PASS  0
 #define KSFT_FAIL  1
diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
index f02cc8a2e4ae..2cc819006424 100644
--- a/tools/testing/selftests/lib.mk
+++ b/tools/testing/selftests/lib.mk
@@ -197,7 +197,7 @@ clean: $(if $(TEST_GEN_MODS_DIR),clean_mods_dir)
 	$(CLEAN)
 
 # Build with _GNU_SOURCE by default
-CFLAGS += -D_GNU_SOURCE=
+CFLAGS += -D_GNU_SOURCE= -D_LARGEFILE64_SOURCE
 
 # Additional include paths needed by kselftest.h and local headers
 CFLAGS += -I${top_srcdir}/tools/testing/selftests
diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c
index fb4600570e13..aee6be530ccb 100644
--- a/tools/testing/selftests/mm/hugetlb_dio.c
+++ b/tools/testing/selftests/mm/hugetlb_dio.c
@@ -22,12 +22,9 @@
 #include "kselftest.h"
 #include "hugepage_settings.h"
 
-#ifndef STATX_DIOALIGN
-#define STATX_DIOALIGN		0x00002000U
-#endif
-
 static int get_dio_alignment(int fd)
 {
+#ifdef STATX_DIOALIGN
 	struct statx stx;
 	int ret;
 
@@ -43,6 +40,9 @@ static int get_dio_alignment(int fd)
 		return 1;
 
 	return stx.stx_dio_offset_align;
+#else
+	return -1;
+#endif
 }
 
 static bool check_dio_alignment(unsigned int start_off,
diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
index 647779653da0..031c79ed067e 100644
--- a/tools/testing/selftests/mm/mdwe_test.c
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
+#include "kselftest_harness.h"
+
 #ifdef __aarch64__
 #include <asm/hwcap.h>
 #endif
@@ -14,8 +16,6 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#include "kselftest_harness.h"
-
 #ifndef __aarch64__
 # define PROT_BTI	0
 #endif
-- 
2.43.0