[PATCH RFC v3 2/2] selftests/mm: Create ADDR_LIMIT_47BIT test

[Charlie Jenkins <charlie@xxxxxxxxxxxx>]

Add a selftest for the ADDR_LIMIT_47BIT personality flag that mmaps
until it runs out of space and ensures no addresses are allocated above
47 bits.

Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
---
 tools/testing/selftests/mm/.gitignore              |  1 +
 tools/testing/selftests/mm/Makefile                |  1 +
 tools/testing/selftests/mm/map_47bit_personality.c | 34 ++++++++++++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore
index da030b43e43b..918ef05e180d 100644
--- a/tools/testing/selftests/mm/.gitignore
+++ b/tools/testing/selftests/mm/.gitignore
@@ -32,6 +32,7 @@ mlock-random-test
 virtual_address_range
 gup_test
 va_128TBswitch
+map_47bit_personality
 map_fixed_noreplace
 write_to_hugetlbfs
 hmm-tests
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index cfad627e8d94..2e95fd545409 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -50,6 +50,7 @@ TEST_GEN_FILES += hugepage-shm
 TEST_GEN_FILES += hugepage-vmemmap
 TEST_GEN_FILES += khugepaged
 TEST_GEN_FILES += madv_populate
+TEST_GEN_FILES += map_47bit_personality
 TEST_GEN_FILES += map_fixed_noreplace
 TEST_GEN_FILES += map_hugetlb
 TEST_GEN_FILES += map_populate
diff --git a/tools/testing/selftests/mm/map_47bit_personality.c b/tools/testing/selftests/mm/map_47bit_personality.c
new file mode 100644
index 000000000000..453412990c21
--- /dev/null
+++ b/tools/testing/selftests/mm/map_47bit_personality.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test the ADDR_LIMIT_47BIT personality flag.
+ */
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include "../kselftest.h"
+
+#define LENGTH (100000000)
+
+#define ADDR_LIMIT_47BIT	0x10000000
+#define BIT47			1UL << 47
+
+/*
+ * Map memory with ADDR_LIMIT_47BIT until no memory left. Ensure that all returned
+ * addresses are below 47 bits.
+ */
+int main(int argc, char **argv)
+{
+	void *addr;
+
+	syscall(__NR_personality, ADDR_LIMIT_47BIT);
+
+	do {
+		addr = mmap(0, LENGTH, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	} while (addr != MAP_FAILED && (unsigned long)addr < BIT47);
+
+	if (errno == ENOMEM)
+		ksft_test_result_pass("ADDR_LIMIT_47BIT works\n");
+	else
+		ksft_test_result_fail("mmap returned address above 47 bits with ADDR_LIMIT_47BIT with addr: %p and err: %s\n",
+				      addr, strerror(errno));
+}

-- 
2.45.0