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SubjectRe: [PATCH] arm64: kaslr: Fix kaslr end boundary of virt addr
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On 2017/11/21 11:44, Chen Feng wrote:
> With kaslr and kasan enable both, I got the follow issue.
>
> [ 16.130523s]kasan: reg->base = 100000000, phys_end =1c0000000,start = ffffffff40000000, end = ffffffc000000000
> [ 16.142517s]___alloc_bootmem_nopanic:257
> [ 16.148284s]__alloc_memory_core_early:63, addr = 197fc7fc0
> [ 16.155670s]__alloc_memory_core_early:65, virt = ffffffffd7fc7fc0
> [ 16.163635s]__alloc_memory_core_early:67, toshow = ffffff8ffaff8ff8
> [ 16.171783s]__alloc_memory_core_early:69, show_phy = ffffffe2649f8ff8
> [ 16.180145s]Unable to handle kernel paging request at virtual address ffffff8ffaff8ff8
> [ 16.189971s]pgd = ffffffad9c507000
> [ 16.195220s][ffffff8ffaff8ff8] *pgd=0000000197fc8003, *pud=0000000197fc8003
>
> *reg->base = 100000000, phys_end =1c0000000,start = ffffffff40000000, end = ffffffc000000000*
>
> memstart_addr 0
> ARM64_MEMSTART_ALIGN 0x40000000
> memstart_offset_seed 0xffc7
> PHYS_OFFSET = 0 - memstart_addr = 0 - 3E40000000 = FFFFFFC1C0000000
>
> reg->base = 0x100000000 -> 0xffffffff40000000
> phys_end = 0x1c0000000 -> 0xffffffc000000000 This is confused, end less than start.
>
> And In memblock it use "start_addr + size" as the end addr. So in function kasan_init,
> if the start >= end, it will not map the hole block address. But the memory in this
> block is valid. And it can be allocated as well.
>
> So donot use the last memory region. Changing "range = range / ARM64_MEMSTART_ALIGN + 1" to
> range = range / ARM64_MEMSTART_ALIGN;
>
> Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
> Signed-off-by: Chen Xiang <chenxiang9@huawei.com>
> ---
> arch/arm64/mm/init.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 716d122..60112c0 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -267,11 +267,8 @@ void __init arm64_memblock_init(void)
> * margin, the size of the region that the available physical
> * memory spans, randomize the linear region as well.
> */
> - if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
> - range = range / ARM64_MEMSTART_ALIGN + 1;
> - memstart_addr -= ARM64_MEMSTART_ALIGN *
> - ((range * memstart_offset_seed) >> 16);
> - }
> + if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN)
> + memstart_addr -= (range * memstart_offset_seed) >> 16;
> }
Sorry, here is not align to ARM64_MEMSTART_ALIGN

Should be:
if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
range = range / ARM64_MEMSTART_ALIGN;
memstart_addr -= ARM64_MEMSTART_ALIGN *
((range * memstart_offset_seed) >> 16);
}

>
> /*
>

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