linux-kernel - [PATCH] tools: testing: add simple __mmap

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Message-ID: <20241213162409.41498-1-lorenzo.stoakes@oracle.com>
Date: Fri, 13 Dec 2024 16:24:09 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] tools: testing: add simple __mmap_region() userland test

Introduce demonstrative, basic, __mmap_region() test upon which we can base
further work upon moving forwards.

This simply asserts that mappings can be made and merges occur as expected.

As part of this change, fix the security_vm_enough_memory_mm() stub which
was previously incorrectly implemented.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
 tools/testing/vma/vma.c          | 53 ++++++++++++++++++++++++++++++++
 tools/testing/vma/vma_internal.h |  2 +-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c
index 920fba58884e..04ab45e27fb8 100644
--- a/tools/testing/vma/vma.c
+++ b/tools/testing/vma/vma.c
@@ -1574,6 +1574,57 @@ static bool test_expand_only_mode(void)
 	return true;
 }
 
+static bool test_mmap_region_basic(void)
+{
+	struct mm_struct mm = {};
+	unsigned long addr;
+	struct vm_area_struct *vma;
+	VMA_ITERATOR(vmi, &mm, 0);
+
+	current->mm = &mm;
+
+	/* Map at 0x300000, length 0x3000. */
+	addr = __mmap_region(NULL, 0x300000, 0x3000,
+			     VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
+			     0x300, NULL);
+	ASSERT_EQ(addr, 0x300000);
+
+	/* Map at 0x250000, length 0x3000. */
+	addr = __mmap_region(NULL, 0x250000, 0x3000,
+			     VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
+			     0x250, NULL);
+	ASSERT_EQ(addr, 0x250000);
+
+	/* Map at 0x303000, merging to 0x300000 of length 0x6000. */
+	addr = __mmap_region(NULL, 0x303000, 0x3000,
+			     VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
+			     0x303, NULL);
+	ASSERT_EQ(addr, 0x303000);
+
+	/* Map at 0x24d000, merging to 0x250000 of length 0x6000. */
+	addr = __mmap_region(NULL, 0x24d000, 0x3000,
+			     VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
+			     0x24d, NULL);
+	ASSERT_EQ(addr, 0x24d000);
+
+	ASSERT_EQ(mm.map_count, 2);
+
+	for_each_vma(vmi, vma) {
+		if (vma->vm_start == 0x300000) {
+			ASSERT_EQ(vma->vm_end, 0x306000);
+			ASSERT_EQ(vma->vm_pgoff, 0x300);
+		} else if (vma->vm_start == 0x24d000) {
+			ASSERT_EQ(vma->vm_end, 0x253000);
+			ASSERT_EQ(vma->vm_pgoff, 0x24d);
+		} else {
+			ASSERT_FALSE(true);
+		}
+	}
+
+	cleanup_mm(&mm, &vmi);
+	return true;
+}
+
 int main(void)
 {
 	int num_tests = 0, num_fail = 0;
@@ -1607,6 +1658,8 @@ int main(void)
 	TEST(copy_vma);
 	TEST(expand_only_mode);
 
+	TEST(mmap_region_basic);
+
 #undef TEST
 
 	printf("%d tests run, %d passed, %d failed.\n",
diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
index 3eeb1317cc69..86f958608645 100644
--- a/tools/testing/vma/vma_internal.h
+++ b/tools/testing/vma/vma_internal.h
@@ -985,7 +985,7 @@ static inline bool is_file_hugepages(struct file *)
 
 static inline int security_vm_enough_memory_mm(struct mm_struct *, long)
 {
-	return true;
+	return 0;
 }
 
 static inline bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long)
-- 
2.47.1