riscv: Fix asan-stack clang build

Nathan reported that because KASAN_SHADOW_OFFSET was not defined in Kconfig, it prevents asan-stack from getting disabled with clang even when CONFIG_KASAN_STACK is disabled: fix this by defining the corresponding config. Reported-by: Nathan Chancellor <[email protected]> Signed-off-by: Alexandre Ghiti <[email protected]> Fixes: 8ad8b72 ("riscv: Add KASAN support") Cc: [email protected] Signed-off-by: Palmer Dabbelt <[email protected]>
josf · Oct 29, 2021 · 54c5639 · 54c5639
1 parent cf11d01
commit 54c5639
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Showing 3 changed files with 10 additions and 2 deletions.
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
@@ -163,6 +163,12 @@ config PAGE_OFFSET
 	default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
 	default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
 
+config KASAN_SHADOW_OFFSET
+	hex
+	depends on KASAN_GENERIC
+	default 0xdfffffc800000000 if 64BIT
+	default 0xffffffff if 32BIT
+
 config ARCH_FLATMEM_ENABLE
 	def_bool !NUMA
 

diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h
@@ -30,8 +30,7 @@
 #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)))
+#define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
 
 void kasan_init(void);
 asmlinkage void kasan_early_init(void);

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
@@ -17,6 +17,9 @@ asmlinkage void __init kasan_early_init(void)
 	uintptr_t i;
 	pgd_t *pgd = early_pg_dir + pgd_index(KASAN_SHADOW_START);
 
+	BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
+		KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
+
 	for (i = 0; i < PTRS_PER_PTE; ++i)
 		set_pte(kasan_early_shadow_pte + i,
 			mk_pte(virt_to_page(kasan_early_shadow_page),