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-rw-r--r--tools/testing/selftests/mm/soft-dirty.c127
-rw-r--r--tools/testing/vma/vma.c3
-rw-r--r--tools/testing/vma/vma_internal.h49
3 files changed, 177 insertions, 2 deletions
diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
index 4ee4db3750c1..c3a9585de98c 100644
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -184,6 +184,130 @@ static void test_mprotect(int pagemap_fd, int pagesize, bool anon)
close(test_fd);
}
+static void test_merge(int pagemap_fd, int pagesize)
+{
+ char *reserved, *map, *map2;
+
+ /*
+ * Reserve space for tests:
+ *
+ * ---padding to ---
+ * | avoid adj. |
+ * v merge v
+ * |---|---|---|---|---|
+ * | | 1 | 2 | 3 | |
+ * |---|---|---|---|---|
+ */
+ reserved = mmap(NULL, 5 * pagesize, PROT_NONE,
+ MAP_ANON | MAP_PRIVATE, -1, 0);
+ if (reserved == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed\n");
+ munmap(reserved, 4 * pagesize);
+
+ /*
+ * Establish initial VMA:
+ *
+ * S/D
+ * |---|---|---|---|---|
+ * | | 1 | | | |
+ * |---|---|---|---|---|
+ */
+ map = mmap(&reserved[pagesize], pagesize, PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);
+ if (map == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed\n");
+
+ /* This will clear VM_SOFTDIRTY too. */
+ clear_softdirty();
+
+ /*
+ * Now place a new mapping which will be marked VM_SOFTDIRTY. Away from
+ * map:
+ *
+ * - S/D
+ * |---|---|---|---|---|
+ * | | 1 | | 2 | |
+ * |---|---|---|---|---|
+ */
+ map2 = mmap(&reserved[3 * pagesize], pagesize, PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);
+ if (map2 == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed\n");
+
+ /*
+ * Now remap it immediately adjacent to map, if the merge correctly
+ * propagates VM_SOFTDIRTY, we should then observe the VMA as a whole
+ * being marked soft-dirty:
+ *
+ * merge
+ * S/D
+ * |---|-------|---|---|
+ * | | 1 | | |
+ * |---|-------|---|---|
+ */
+ map2 = mremap(map2, pagesize, pagesize, MREMAP_FIXED | MREMAP_MAYMOVE,
+ &reserved[2 * pagesize]);
+ if (map2 == MAP_FAILED)
+ ksft_exit_fail_msg("mremap failed\n");
+ ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 1,
+ "Test %s-anon soft-dirty after remap merge 1st pg\n",
+ __func__);
+ ksft_test_result(pagemap_is_softdirty(pagemap_fd, map2) == 1,
+ "Test %s-anon soft-dirty after remap merge 2nd pg\n",
+ __func__);
+
+ munmap(map, 2 * pagesize);
+
+ /*
+ * Now establish another VMA:
+ *
+ * S/D
+ * |---|---|---|---|---|
+ * | | 1 | | | |
+ * |---|---|---|---|---|
+ */
+ map = mmap(&reserved[pagesize], pagesize, PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);
+ if (map == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed\n");
+
+ /* Clear VM_SOFTDIRTY... */
+ clear_softdirty();
+ /* ...and establish incompatible adjacent VMA:
+ *
+ * - S/D
+ * |---|---|---|---|---|
+ * | | 1 | 2 | | |
+ * |---|---|---|---|---|
+ */
+ map2 = mmap(&reserved[2 * pagesize], pagesize,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);
+ if (map2 == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed\n");
+
+ /*
+ * Now mprotect() VMA 1 so it's compatible with 2 and therefore merges:
+ *
+ * merge
+ * S/D
+ * |---|-------|---|---|
+ * | | 1 | | |
+ * |---|-------|---|---|
+ */
+ if (mprotect(map, pagesize, PROT_READ | PROT_WRITE | PROT_EXEC))
+ ksft_exit_fail_msg("mprotect failed\n");
+
+ ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 1,
+ "Test %s-anon soft-dirty after mprotect merge 1st pg\n",
+ __func__);
+ ksft_test_result(pagemap_is_softdirty(pagemap_fd, map2) == 1,
+ "Test %s-anon soft-dirty after mprotect merge 2nd pg\n",
+ __func__);
+
+ munmap(map, 2 * pagesize);
+}
+
static void test_mprotect_anon(int pagemap_fd, int pagesize)
{
test_mprotect(pagemap_fd, pagesize, true);
@@ -204,7 +328,7 @@ int main(int argc, char **argv)
if (!softdirty_supported())
ksft_exit_skip("soft-dirty is not support\n");
- ksft_set_plan(15);
+ ksft_set_plan(19);
pagemap_fd = open(PAGEMAP_FILE_PATH, O_RDONLY);
if (pagemap_fd < 0)
ksft_exit_fail_msg("Failed to open %s\n", PAGEMAP_FILE_PATH);
@@ -216,6 +340,7 @@ int main(int argc, char **argv)
test_hugepage(pagemap_fd, pagesize);
test_mprotect_anon(pagemap_fd, pagesize);
test_mprotect_file(pagemap_fd, pagesize);
+ test_merge(pagemap_fd, pagesize);
close(pagemap_fd);
diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c
index 656e1c75b711..fd37ce3b2628 100644
--- a/tools/testing/vma/vma.c
+++ b/tools/testing/vma/vma.c
@@ -339,6 +339,7 @@ static bool test_simple_modify(void)
struct mm_struct mm = {};
struct vm_area_struct *init_vma = alloc_vma(&mm, 0, 0x3000, 0, vm_flags);
VMA_ITERATOR(vmi, &mm, 0x1000);
+ vm_flags_t flags = VM_READ | VM_MAYREAD;
ASSERT_FALSE(attach_vma(&mm, init_vma));
@@ -347,7 +348,7 @@ static bool test_simple_modify(void)
* performs the merge/split only.
*/
vma = vma_modify_flags(&vmi, init_vma, init_vma,
- 0x1000, 0x2000, VM_READ | VM_MAYREAD);
+ 0x1000, 0x2000, &flags);
ASSERT_NE(vma, NULL);
/* We modify the provided VMA, and on split allocate new VMAs. */
ASSERT_EQ(vma, init_vma);
diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
index 9f724954a0f6..f64064ee4858 100644
--- a/tools/testing/vma/vma_internal.h
+++ b/tools/testing/vma/vma_internal.h
@@ -56,6 +56,7 @@ extern unsigned long dac_mmap_min_addr;
#define VM_MAYEXEC 0x00000040
#define VM_GROWSDOWN 0x00000100
#define VM_PFNMAP 0x00000400
+#define VM_MAYBE_GUARD 0x00000800
#define VM_LOCKED 0x00002000
#define VM_IO 0x00004000
#define VM_SEQ_READ 0x00008000 /* App will access data sequentially */
@@ -116,6 +117,54 @@ extern unsigned long dac_mmap_min_addr;
#define VM_SEALED VM_NONE
#endif
+/*
+ * Flags which should be 'sticky' on merge - that is, flags which, when one VMA
+ * possesses it but the other does not, the merged VMA should nonetheless have
+ * applied to it:
+ *
+ * VM_SOFTDIRTY - if a VMA is marked soft-dirty, that is has not had its
+ * references cleared via /proc/$pid/clear_refs, any merged VMA
+ * should be considered soft-dirty also as it operates at a VMA
+ * granularity.
+ */
+#define VM_STICKY (VM_SOFTDIRTY | VM_MAYBE_GUARD)
+
+/*
+ * VMA flags we ignore for the purposes of merge, i.e. one VMA possessing one
+ * of these flags and the other not does not preclude a merge.
+ *
+ * VM_STICKY - When merging VMAs, VMA flags must match, unless they are
+ * 'sticky'. If any sticky flags exist in either VMA, we simply
+ * set all of them on the merged VMA.
+ */
+#define VM_IGNORE_MERGE VM_STICKY
+
+/*
+ * Flags which should result in page tables being copied on fork. These are
+ * flags which indicate that the VMA maps page tables which cannot be
+ * reconsistuted upon page fault, so necessitate page table copying upon
+ *
+ * VM_PFNMAP / VM_MIXEDMAP - These contain kernel-mapped data which cannot be
+ * reasonably reconstructed on page fault.
+ *
+ * VM_UFFD_WP - Encodes metadata about an installed uffd
+ * write protect handler, which cannot be
+ * reconstructed on page fault.
+ *
+ * We always copy pgtables when dst_vma has uffd-wp
+ * enabled even if it's file-backed
+ * (e.g. shmem). Because when uffd-wp is enabled,
+ * pgtable contains uffd-wp protection information,
+ * that's something we can't retrieve from page cache,
+ * and skip copying will lose those info.
+ *
+ * VM_MAYBE_GUARD - Could contain page guard region markers which
+ * by design are a property of the page tables
+ * only and thus cannot be reconstructed on page
+ * fault.
+ */
+#define VM_COPY_ON_FORK (VM_PFNMAP | VM_MIXEDMAP | VM_UFFD_WP | VM_MAYBE_GUARD)
+
#define FIRST_USER_ADDRESS 0UL
#define USER_PGTABLES_CEILING 0UL
generated by cgit v1.2.3 (git 2.25.1) at 2026-07-03 18:21:02 +0000