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-rw-r--r--arch/arm64/include/asm/memory.h45
1 files changed, 34 insertions, 11 deletions
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index fde4186cc3..d82305ab42 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -65,15 +65,41 @@
#define KERNEL_END _end
/*
- * Generic and tag-based KASAN require 1/8th and 1/16th of the kernel virtual
- * address space for the shadow region respectively. They can bloat the stack
- * significantly, so double the (minimum) stack size when they are in use.
+ * Generic and Software Tag-Based KASAN modes require 1/8th and 1/16th of the
+ * kernel virtual address space for storing the shadow memory respectively.
+ *
+ * The mapping between a virtual memory address and its corresponding shadow
+ * memory address is defined based on the formula:
+ *
+ * shadow_addr = (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET
+ *
+ * where KASAN_SHADOW_SCALE_SHIFT is the order of the number of bits that map
+ * to a single shadow byte and KASAN_SHADOW_OFFSET is a constant that offsets
+ * the mapping. Note that KASAN_SHADOW_OFFSET does not point to the start of
+ * the shadow memory region.
+ *
+ * Based on this mapping, we define two constants:
+ *
+ * KASAN_SHADOW_START: the start of the shadow memory region;
+ * KASAN_SHADOW_END: the end of the shadow memory region.
+ *
+ * KASAN_SHADOW_END is defined first as the shadow address that corresponds to
+ * the upper bound of possible virtual kernel memory addresses UL(1) << 64
+ * according to the mapping formula.
+ *
+ * KASAN_SHADOW_START is defined second based on KASAN_SHADOW_END. The shadow
+ * memory start must map to the lowest possible kernel virtual memory address
+ * and thus it depends on the actual bitness of the address space.
+ *
+ * As KASAN inserts redzones between stack variables, this increases the stack
+ * memory usage significantly. Thus, we double the (minimum) stack size.
*/
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
-#define KASAN_SHADOW_END ((UL(1) << (64 - KASAN_SHADOW_SCALE_SHIFT)) \
- + KASAN_SHADOW_OFFSET)
-#define PAGE_END (KASAN_SHADOW_END - (1UL << (vabits_actual - KASAN_SHADOW_SCALE_SHIFT)))
+#define KASAN_SHADOW_END ((UL(1) << (64 - KASAN_SHADOW_SCALE_SHIFT)) + KASAN_SHADOW_OFFSET)
+#define _KASAN_SHADOW_START(va) (KASAN_SHADOW_END - (UL(1) << ((va) - KASAN_SHADOW_SCALE_SHIFT)))
+#define KASAN_SHADOW_START _KASAN_SHADOW_START(vabits_actual)
+#define PAGE_END KASAN_SHADOW_START
#define KASAN_THREAD_SHIFT 1
#else
#define KASAN_THREAD_SHIFT 0
@@ -182,6 +208,7 @@
#include <linux/types.h>
#include <asm/boot.h>
#include <asm/bug.h>
+#include <asm/sections.h>
#if VA_BITS > 48
extern u64 vabits_actual;
@@ -193,15 +220,12 @@ extern s64 memstart_addr;
/* PHYS_OFFSET - the physical address of the start of memory. */
#define PHYS_OFFSET ({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })
-/* the virtual base of the kernel image */
-extern u64 kimage_vaddr;
-
/* the offset between the kernel virtual and physical mappings */
extern u64 kimage_voffset;
static inline unsigned long kaslr_offset(void)
{
- return kimage_vaddr - KIMAGE_VADDR;
+ return (u64)&_text - KIMAGE_VADDR;
}
#ifdef CONFIG_RANDOMIZE_BASE
@@ -407,6 +431,5 @@ void dump_mem_limit(void);
#define INIT_MEMBLOCK_MEMORY_REGIONS (INIT_MEMBLOCK_REGIONS * 8)
#endif
-#include <asm-generic/memory_model.h>
#endif /* __ASM_MEMORY_H */