Re: [Crash-utility] Not compatible with d52888aa2753 ("x86/mm: Move LDT remap out of KASLR region on 5-level paging")

----- Original Message ----- > commit d52888aa2753 ("x86/mm: Move LDT remap out of KASLR region on > 5-level paging") changed PAGE_OFFSET from 0xffff880000000000 to > 0xffff888000000000. > > crash can't open such with CONFIG_RANDOMIZE_BASE=n: > > crash: read error: kernel virtual address: ffff888ffe605024 type: > "tss_struct ist array" > > Edit defs.h: > > -#define PAGE_OFFSET_2_6_27 0xffff880000000000 > +#define PAGE_OFFSET_2_6_27 0xffff888000000000 > > And this works for me. > > (d52888aa2753 has also been included in 4.14.84) Ah, so your kernel does not have "page_offset_base", which simplifies things for KASLR kernels. I don't have any sample vmcores that are not configured with CONFIG_RANDOMIZE_BASE. Obviously just changing PAGE_OFFSET_2_6_27 in the crash utility as above cannot be done for backwards compatibility purposes. There would have to be 2 adjustments in the crash utility for the kernel change: -#define __PAGE_OFFSET_BASE_L5 _AC(0xff10000000000000, UL) -#define __PAGE_OFFSET_BASE_L4 _AC(0xffff880000000000, UL) +#define __PAGE_OFFSET_BASE_L5 _AC(0xff11000000000000, UL) +#define __PAGE_OFFSET_BASE_L4 _AC(0xffff888000000000, UL) where the crash utility uses PAGE_OFFSET_2_6_27 and PAGE_OFFSET_5LEVEL #define PAGE_OFFSET_2_6_27 0xffff880000000000 and #define PAGE_OFFSET_5LEVEL 0xff10000000000000 > > (d52888aa2753 has also been included in 4.14.84) > And that's a problem. We could gate the setting of machdep->machspec->page_offset on LINUX(4, 20, 0), but since it's been backported, there needs to be another way to best determine which PAGE_OFFSET value to use when KASLR is not in effect. Dave > > Thanks > WANG Chao > > -- > Crash-utility mailing list > Crash-utility(a)redhat.com > https://www.redhat.com/mailman/listinfo/crash-utility > -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility