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    Subject[PATCH v2 12/37] kasan, arm64: only init shadow for software modes
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    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>
    ---
    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;
    --
    2.28.0.618.gf4bc123cb7-goog
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