[PATCH RFC v2 08/25] kmsan: reduce vmalloc space

[glider@google.com]

KMSAN is going to use 3/4 of existing vmalloc space to hold the
metadata, therefore we lower VMALLOC_END to make sure vmalloc() doesn't
allocate past the first 1/4.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org

---

Change-Id: Iaa5e8e0fc2aa66c956f937f5a1de6e5ef40d57cc
---
 arch/x86/include/asm/pgtable_64_types.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 52e5f5f2240d..586629e20436 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -139,7 +139,22 @@ extern unsigned int ptrs_per_p4d;
 # define VMEMMAP_START		__VMEMMAP_BASE_L4
 #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */
 
+#ifndef CONFIG_KMSAN
 #define VMALLOC_END		(VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1)
+#else
+/*
+ * In KMSAN builds vmalloc area is four times smaller, and the remaining 3/4
+ * are used to keep the metadata for virtual pages.
+ */
+#define VMALLOC_QUARTER_SIZE	((VMALLOC_SIZE_TB << 40) >> 2)
+#define VMALLOC_END		(VMALLOC_START + VMALLOC_QUARTER_SIZE - 1)
+#define VMALLOC_SHADOW_OFFSET	VMALLOC_QUARTER_SIZE
+#define VMALLOC_ORIGIN_OFFSET	(VMALLOC_QUARTER_SIZE * 2)
+#define VMALLOC_META_END	(VMALLOC_END + VMALLOC_ORIGIN_OFFSET)
+#define MODULES_SHADOW_START	(VMALLOC_META_END + 1)
+#define MODULES_ORIGIN_START	(MODULES_SHADOW_START + MODULES_LEN)
+#define MODULES_ORIGIN_END	(MODULES_ORIGIN_START + MODULES_LEN)
+#endif
 
 #define MODULES_VADDR		(__START_KERNEL_map + KERNEL_IMAGE_SIZE)
 /* The module sections ends with the start of the fixmap */
-- 
2.24.0.rc0.303.g954a862665-goog