[PATCH v3 14/39] kasan, arm64: only init shadow for software modes

Andrey Konovalov
2020-09-24T22:51:41Z

This is a preparatory commit for the upcoming addition of a new hardware
tag-based (MTE-based) KASAN mode.

Hardware tag-based KASAN won't be using shadow memory. Only initialize
it when one of the software KASAN modes are enabled.

No functional changes for software modes.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
Change-Id: I055e0651369b14d3e54cdaa8c48e6329b2e8952d
---
arch/arm64/include/asm/kasan.h | 8 ++++++--
arch/arm64/mm/kasan_init.c | 15 ++++++++++++++-
2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h
index b0dc4abc3589..f7ea70d02cab 100644
--- a/arch/arm64/include/asm/kasan.h
+++ b/arch/arm64/include/asm/kasan.h
@@ -13,6 +13,12 @@
#define arch_kasan_get_tag(addr) __tag_get(addr)

#ifdef CONFIG_KASAN
+void kasan_init(void);
+#else
+static inline void kasan_init(void) { }
+#endif
+
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)

/*
* KASAN_SHADOW_START: beginning of the kernel virtual addresses.
@@ -33,12 +39,10 @@
#define _KASAN_SHADOW_START(va) (KASAN_SHADOW_END - (1UL << ((va) - KASAN_SHADOW_SCALE_SHIFT)))
#define KASAN_SHADOW_START _KASAN_SHADOW_START(vabits_actual)

-void kasan_init(void);
void kasan_copy_shadow(pgd_t *pgdir);
asmlinkage void kasan_early_init(void);

#else
-static inline void kasan_init(void) { }
static inline void kasan_copy_shadow(pgd_t *pgdir) { }
#endif

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 7291b26ce788..4d35eaf3ec97 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -21,6 +21,8 @@
#include <asm/sections.h>
#include <asm/tlbflush.h>

+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+
static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);

/*
@@ -208,7 +210,7 @@ static void __init clear_pgds(unsigned long start,
set_pgd(pgd_offset_k(start), __pgd(0));
}

-void __init kasan_init(void)
+static void __init kasan_init_shadow(void)
{
u64 kimg_shadow_start, kimg_shadow_end;
u64 mod_shadow_start, mod_shadow_end;
@@ -269,6 +271,17 @@ void __init kasan_init(void)

memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+}
+
+#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) */
+
+static inline void __init kasan_init_shadow(void) { }
+
+#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
+
+void __init kasan_init(void)
+{
+ kasan_init_shadow();

/* At this point kasan is fully initialized. Enable error messages */
init_task.kasan_depth = 0;
--
2.28.0.681.g6f77f65b4e-goog