From: Chaitanya S Prakash chaitanyas.prakash@arm.com
Attempting to remap a range larger than what is owned by the capability triggers a -EINVAL error. Additionally, mappings that have to be moved in order to satisfy the new constraints, expect the MREMAP_MAYMOVE flag to be specified. Failure to do so triggers the -ENOMEM error. Within the bounds of a reservation, mremap() can be used to grow the mappings in-place. Tests to verify this behaviour have been added.
Signed-off-by: Chaitanya S Prakash chaitanyas.prakash@arm.com --- tools/testing/selftests/arm64/morello/mmap.c | 56 ++++++++++++++++++++ 1 file changed, 56 insertions(+)
diff --git a/tools/testing/selftests/arm64/morello/mmap.c b/tools/testing/selftests/arm64/morello/mmap.c index cb8da2e257a9..dfdba7833601 100644 --- a/tools/testing/selftests/arm64/morello/mmap.c +++ b/tools/testing/selftests/arm64/morello/mmap.c @@ -357,6 +357,61 @@ TEST(test_check_mmap_reservation) ASSERT_EQ(retval, 0); }
+/* test to verify mremap() reservation semantics */ +TEST(test_check_mremap_reservation) +{ + void *ptr, *new_ptr; + int retval; + int prot = PROT_READ | PROT_WRITE; + int flags = MAP_PRIVATE | MAP_ANONYMOUS; + + /* expanding a mapping with MREMAP_MAYMOVE flag specified */ + ptr = mmap(NULL, MMAP_SIZE_REDUCED, prot, flags, -1, 0); + ASSERT_FALSE(IS_ERR_VALUE(ptr)); + + new_ptr = mremap(ptr, MMAP_SIZE_REDUCED, MMAP_SIZE, MREMAP_MAYMOVE, NULL); + ASSERT_FALSE(IS_ERR_VALUE(new_ptr)); + ASSERT_NE(ptr, new_ptr); + EXPECT_EQ(0, probe_mem_range(new_ptr, MMAP_SIZE, + PROBE_MODE_TOUCH | PROBE_MODE_VERIFY)); + + retval = munmap(new_ptr, MMAP_SIZE); + ASSERT_EQ(retval, 0); + + /* expanding a mapping without MREMAP_MAYMOVE flag triggers an ENOMEM error */ + ptr = mmap(NULL, MMAP_SIZE_REDUCED, prot, flags, -1, 0); + ASSERT_FALSE(IS_ERR_VALUE(ptr)); + + new_ptr = mremap(ptr, MMAP_SIZE_REDUCED, MMAP_SIZE, 0, 0); + EXPECT_EQ((unsigned long)new_ptr, (unsigned long)-ENOMEM); + + retval = munmap(ptr, MMAP_SIZE_REDUCED); + ASSERT_EQ(retval, 0); + + /* attempt to resize a mapping range greater than what the capability owns */ + ptr = mmap(NULL, MMAP_SIZE_REDUCED, prot, flags, -1, 0); + ASSERT_FALSE(IS_ERR_VALUE(ptr)); + + new_ptr = mremap(ptr, MMAP_SIZE, MMAP_SIZE, MREMAP_MAYMOVE, 0); + EXPECT_EQ((unsigned long)new_ptr, (unsigned long)-EINVAL); + + retval = munmap(ptr, MMAP_SIZE_REDUCED); + ASSERT_EQ(retval, 0); + + /* attempt to grow mappings in-place */ + ptr = mmap(NULL, MMAP_SIZE, prot, flags, -1, 0); + ASSERT_FALSE(IS_ERR_VALUE(ptr)); + + retval = munmap(ptr + MMAP_SIZE_REDUCED, MMAP_SIZE_REDUCED); + ASSERT_EQ(retval, 0); + + new_ptr = mremap(ptr, MMAP_SIZE_REDUCED, MMAP_SIZE, 0, 0); + ASSERT_FALSE(IS_ERR_VALUE(new_ptr)); + + retval = munmap(new_ptr, MMAP_SIZE); + EXPECT_EQ(retval, 0); +} + int main(int argc __maybe_unused, char **argv __maybe_unused, char **envp __maybe_unused, struct morello_auxv *auxv) { pagesize = get_pagesize(auxv); @@ -367,5 +422,6 @@ int main(int argc __maybe_unused, char **argv __maybe_unused, char **envp __mayb test_validity_tag_check(); test_range_check(); test_check_mmap_reservation(); + test_check_mremap_reservation(); return 0; }