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 <nathan@kernel.org>
Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
Fixes: 8ad8b72721d0 ("riscv: Add KASAN support")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c3f3fd5..6d5b63b 100644 (file)
--- 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
index a2b3d9c..b00f503 100644 (file)
--- 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
index 89a8376..54294f8 100644 (file)
--- 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),