On 07/27/2015 06:59 PM, Catalin Marinas wrote:
> On Fri, Jul 24, 2015 at 07:41:57PM +0300, Andrey Ryabinin wrote:
>> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
>> index 4d2a925..2cacf55 100644
>> --- a/arch/arm64/Makefile
>> +++ b/arch/arm64/Makefile
>> @@ -40,6 +40,12 @@ else
>> TEXT_OFFSET := 0x00080000
>> endif
>>
>> +# KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - 3)) - (1 << 61)
>> +KASAN_SHADOW_OFFSET := $(shell printf "0x%x\n" $$(( \
>> + (-1 << $(CONFIG_ARM64_VA_BITS)) \
>> + + (1 << ($(CONFIG_ARM64_VA_BITS) - 3)) \
>> + - (1 << (64 - 3)) )) )
>
> Does this work with any POSIX shell? Do we always have a 64-bit type?
> As I wasn't sure about this, I suggested awk (or perl).
>
Ok, It will be safer to use 32-bit arithmetic.
I've checked this on 32-bit bash, however this doesn't guarantee that it works with
any other version of bash or another shell.
>> +static void __init clear_pgds(unsigned long start,
>> + unsigned long end)
>> +{
>> + /*
>> + * Remove references to kasan page tables from
>> + * swapper_pg_dir. pgd_clear() can't be used
>> + * here because it's nop on 2,3-level pagetable setups
>> + */
>> + for (; start && start < end; start += PGDIR_SIZE)
>> + set_pgd(pgd_offset_k(start), __pgd(0));
>> +}
>
> I don't think we need the "start" check, just "start < end". Do you
> expect a start == 0 (or overflow)?
Right, we don't need this.
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