selftest mm/mseal: fix test_seal_mremap_move_dontunmap_anyaddr

the syscall remap accepts following:

mremap(src, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP, dst)

when the src is sealed, the call will fail with error code:
EPERM

Previously, the test uses hard-coded 0xdeaddead as dst, and it
will fail on the system with newer glibc installed.

This patch removes test's dependency on glibc for mremap(), also
fix the test and remove the hardcoded address.

Link: https://lkml.kernel.org/r/20240807212320.2831848-1-jeffxu@chromium.org
Fixes: 4926c7a5 ("selftest mm/mseal memory sealing")
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Reported-by: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/mseal_test.c

@@ -110,6 +110,16 @@ static int sys_madvise(void *start, size_t len, int types)
 	return sret;
 }
 
+static void *sys_mremap(void *addr, size_t old_len, size_t new_len,
+	unsigned long flags, void *new_addr)
+{
+	void *sret;
+
+	errno = 0;
+	sret = (void *) syscall(__NR_mremap, addr, old_len, new_len, flags, new_addr);
+	return sret;
+}
+
 static int sys_pkey_alloc(unsigned long flags, unsigned long init_val)
 {
 	int ret = syscall(__NR_pkey_alloc, flags, init_val);
@@ -1115,12 +1125,12 @@ static void test_seal_mremap_shrink(bool seal)
 	}
 
 	/* shrink from 4 pages to 2 pages. */
-	ret2 = mremap(ptr, size, 2 * page_size, 0, 0);
+	ret2 = sys_mremap(ptr, size, 2 * page_size, 0, 0);
 	if (seal) {
-		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
+		FAIL_TEST_IF_FALSE(ret2 == (void *) MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
 	} else {
-		FAIL_TEST_IF_FALSE(ret2 != MAP_FAILED);
+		FAIL_TEST_IF_FALSE(ret2 != (void *) MAP_FAILED);
 
 	}
 
@@ -1147,7 +1157,7 @@ static void test_seal_mremap_expand(bool seal)
 	}
 
 	/* expand from 2 page to 4 pages. */
-	ret2 = mremap(ptr, 2 * page_size, 4 * page_size, 0, 0);
+	ret2 = sys_mremap(ptr, 2 * page_size, 4 * page_size, 0, 0);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
@@ -1180,7 +1190,7 @@ static void test_seal_mremap_move(bool seal)
 	}
 
 	/* move from ptr to fixed address. */
-	ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, newPtr);
+	ret2 = sys_mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, newPtr);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
@@ -1299,7 +1309,7 @@ static void test_seal_mremap_shrink_fixed(bool seal)
 	}
 
 	/* mremap to move and shrink to fixed address */
-	ret2 = mremap(ptr, size, 2 * page_size, MREMAP_MAYMOVE | MREMAP_FIXED,
+	ret2 = sys_mremap(ptr, size, 2 * page_size, MREMAP_MAYMOVE | MREMAP_FIXED,
 			newAddr);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
@@ -1330,7 +1340,7 @@ static void test_seal_mremap_expand_fixed(bool seal)
 	}
 
 	/* mremap to move and expand to fixed address */
-	ret2 = mremap(ptr, page_size, size, MREMAP_MAYMOVE | MREMAP_FIXED,
+	ret2 = sys_mremap(ptr, page_size, size, MREMAP_MAYMOVE | MREMAP_FIXED,
 			newAddr);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
@@ -1361,7 +1371,7 @@ static void test_seal_mremap_move_fixed(bool seal)
 	}
 
 	/* mremap to move to fixed address */
-	ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, newAddr);
+	ret2 = sys_mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, newAddr);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
@@ -1390,14 +1400,13 @@ static void test_seal_mremap_move_fixed_zero(bool seal)
 	/*
 	 * MREMAP_FIXED can move the mapping to zero address
 	 */
-	ret2 = mremap(ptr, size, 2 * page_size, MREMAP_MAYMOVE | MREMAP_FIXED,
+	ret2 = sys_mremap(ptr, size, 2 * page_size, MREMAP_MAYMOVE | MREMAP_FIXED,
 			0);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
 	} else {
 		FAIL_TEST_IF_FALSE(ret2 == 0);
-
 	}
 
 	REPORT_TEST_PASS();
@@ -1420,13 +1429,13 @@ static void test_seal_mremap_move_dontunmap(bool seal)
 	}
 
 	/* mremap to move, and don't unmap src addr. */
-	ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP, 0);
+	ret2 = sys_mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP, 0);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
 	} else {
+		/* kernel will allocate a new address */
 		FAIL_TEST_IF_FALSE(ret2 != MAP_FAILED);
-
 	}
 
 	REPORT_TEST_PASS();
@@ -1434,7 +1443,7 @@ static void test_seal_mremap_move_dontunmap(bool seal)
 
 static void test_seal_mremap_move_dontunmap_anyaddr(bool seal)
 {
-	void *ptr;
+	void *ptr, *ptr2;
 	unsigned long page_size = getpagesize();
 	unsigned long size = 4 * page_size;
 	int ret;
@@ -1449,24 +1458,30 @@ static void test_seal_mremap_move_dontunmap_anyaddr(bool seal)
 	}
 
 	/*
-	 * The 0xdeaddead should not have effect on dest addr
-	 * when MREMAP_DONTUNMAP is set.
+	 * The new address is any address that not allocated.
+	 * use allocate/free to similate that.
 	 */
-	ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
-			0xdeaddead);
+	setup_single_address(size, &ptr2);
+	FAIL_TEST_IF_FALSE(ptr2 != (void *)-1);
+	ret = sys_munmap(ptr2, size);
+	FAIL_TEST_IF_FALSE(!ret);
+
+	/*
+	 * remap to any address.
+	 */
+	ret2 = sys_mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
+			(void *) ptr2);
 	if (seal) {
 		FAIL_TEST_IF_FALSE(ret2 == MAP_FAILED);
 		FAIL_TEST_IF_FALSE(errno == EPERM);
 	} else {
-		FAIL_TEST_IF_FALSE(ret2 != MAP_FAILED);
-		FAIL_TEST_IF_FALSE((long)ret2 != 0xdeaddead);
-
+		/* remap success and return ptr2 */
+		FAIL_TEST_IF_FALSE(ret2 ==  ptr2);
 	}
 
 	REPORT_TEST_PASS();
 }
 
-
 static void test_seal_merge_and_split(void)
 {
 	void *ptr;