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authorAlexandre Ghiti <alex@ghiti.fr>2021-02-08 14:30:14 -0500
committerPalmer Dabbelt <palmerdabbelt@google.com>2021-02-22 18:44:53 -0800
commit7899ed260c348fe8813150c12c7a59fa0e3e9121 (patch)
tree5b97bec0b564db245034126bd6923f1efad7e1e2 /arch/riscv/include/asm
parent0f02de4481da684aad6589aed0ea47bd1ab391c9 (diff)
downloadlinux-7899ed260c348fe8813150c12c7a59fa0e3e9121.tar.gz
riscv: Improve kasan definitions
There is no functional change here, only improvement in code readability by adding comments to explain where the kasan constants come from and by replacing hardcoded numerical constant by the corresponding define. Note that the comments come from arm64. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/include/asm')
-rw-r--r--arch/riscv/include/asm/kasan.h22
1 files changed, 19 insertions, 3 deletions
diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h
index b04028c6218c..a2b3d9cdbc86 100644
--- a/arch/riscv/include/asm/kasan.h
+++ b/arch/riscv/include/asm/kasan.h
@@ -8,12 +8,28 @@
#ifdef CONFIG_KASAN
+/*
+ * The following comment was copied from arm64:
+ * KASAN_SHADOW_START: beginning of the kernel virtual addresses.
+ * KASAN_SHADOW_END: KASAN_SHADOW_START + 1/N of kernel virtual addresses,
+ * where N = (1 << KASAN_SHADOW_SCALE_SHIFT).
+ *
+ * KASAN_SHADOW_OFFSET:
+ * This value is used to map an address to the corresponding shadow
+ * address by the following formula:
+ * shadow_addr = (address >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET
+ *
+ * (1 << (64 - KASAN_SHADOW_SCALE_SHIFT)) shadow addresses that lie in range
+ * [KASAN_SHADOW_OFFSET, KASAN_SHADOW_END) cover all 64-bits of virtual
+ * addresses. So KASAN_SHADOW_OFFSET should satisfy the following equation:
+ * KASAN_SHADOW_OFFSET = KASAN_SHADOW_END -
+ * (1ULL << (64 - KASAN_SHADOW_SCALE_SHIFT))
+ */
#define KASAN_SHADOW_SCALE_SHIFT 3
-#define KASAN_SHADOW_SIZE (UL(1) << (38 - KASAN_SHADOW_SCALE_SHIFT))
-#define KASAN_SHADOW_START KERN_VIRT_START /* 2^64 - 2^38 */
+#define KASAN_SHADOW_SIZE (UL(1) << ((CONFIG_VA_BITS - 1) - KASAN_SHADOW_SCALE_SHIFT))
+#define KASAN_SHADOW_START KERN_VIRT_START
#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
-
#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_END - (1ULL << \
(64 - KASAN_SHADOW_SCALE_SHIFT)))