• Andrey Ryabinin's avatar
    arm64: add KASAN support · 39d114dd
    Andrey Ryabinin authored
    This patch adds arch specific code for kernel address sanitizer
    (see Documentation/kasan.txt).
    1/8 of kernel addresses reserved for shadow memory. There was no
    big enough hole for this, so virtual addresses for shadow were
    stolen from vmalloc area.
    At early boot stage the whole shadow region populated with just
    one physical page (kasan_zero_page). Later, this page reused
    as readonly zero shadow for some memory that KASan currently
    don't track (vmalloc).
    After mapping the physical memory, pages for shadow memory are
    allocated and mapped.
    Functions like memset/memmove/memcpy do a lot of memory accesses.
    If bad pointer passed to one of these function it is important
    to catch this. Compiler's instrumentation cannot do this since
    these functions are written in assembly.
    KASan replaces memory functions with manually instrumented variants.
    Original functions declared as weak symbols so strong definitions
    in mm/kasan/kasan.c could replace them. Original functions have aliases
    with '__' prefix in name, so we could call non-instrumented variant
    if needed.
    Some files built without kasan instrumentation (e.g. mm/slub.c).
    Original mem* function replaced (via #define) with prefixed variants
    to disable memory access checks for such files.
    Signed-off-by: default avatarAndrey Ryabinin <ryabinin.a.a@gmail.com>
    Tested-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
    Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
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