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    Subject[PATCH 2/2] arm64: Define PAGE_OFFSET using GENMASK_ULL
    Date
    As is the definition causes an integer overflow, which is expected,
    however clang raises the following warning:

    arch/arm64/kernel/head.S:47:8: warning:
    integer overflow in preprocessor expression
    #elif (PAGE_OFFSET & 0x1fffff) != 0
    ^~~~~~~~~~~
    arch/arm64/include/asm/memory.h:52:46: note:
    expanded from macro 'PAGE_OFFSET'
    #define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
    ~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~

    Use GENMASK_ULL() instead of shifting explicitly, the macro takes care
    of avoiding the overflow.

    Reported-by: Nick Desaulniers <ndesaulniers@google.com>
    Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
    ---
    arch/arm64/include/asm/memory.h | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
    index 32f82723338a..732d4eed8edd 100644
    --- a/arch/arm64/include/asm/memory.h
    +++ b/arch/arm64/include/asm/memory.h
    @@ -65,7 +65,7 @@
    */
    #define VA_BITS (CONFIG_ARM64_VA_BITS)
    #define VA_START (UL(0xffffffffffffffff) << VA_BITS)
    -#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
    +#define PAGE_OFFSET GENMASK_ULL(BITS_PER_LONG_LONG - 1, VA_BITS - 1)
    #define KIMAGE_VADDR (MODULES_END)
    #define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
    #define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE)
    --
    2.14.0.rc1.383.gd1ce394fe2-goog
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