On Fri, Aug 30, 2019 at 3:04 PM Donald Buczek <buc...@molgen.mpg.de> wrote: > > Dear Baoquan, > > On 8/30/19 11:23 AM, Baoquan He wrote: > > On 08/30/19 at 11:12am, Donald Buczek wrote: > >> Linux kernel commit d52888aa2753 ("x86/mm: Move LDT remap out of KASLR > >> region on 5-level paging") changed the base of the direct mapping > >> from 0xffff880000000000 to 0xffff888000000000. This was merged > >> into v4.20-rc2. > > > > A good catch and necessary fix, thanks. > > > > Does it have issue in makedumpfile? > > We don't use makedumpfile. We use `cp /proc/vmcore /mnt/crash.vmcore` in the > panic kernel.
That shouldn't be a problem in makedumpfile as we have a generic way to calculate the PAGE_OFFSET value there from the PT_LOADs in the '/proc/kcore' file (which I mentioned in the other email conversation, see [0]): static int get_page_offset_x86_64(void) { <..snip..> if (get_num_pt_loads()) { /* * Linux 4.19 (only) adds KCORE_REMAP PT_LOADs, which have * virt_start < __START_KERNEL_map, to /proc/kcore. In order * not to select them, we select the last valid PT_LOAD. */ for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); i++) { if (virt_start != NOT_KV_ADDR && virt_start < __START_KERNEL_map && phys_start != NOT_PADDR) { page_offset = virt_start - phys_start; } } if (page_offset) { info->page_offset = page_offset; DEBUG_MSG("page_offset : %lx (pt_load)\n", info->page_offset); return TRUE; } } <..snip..> Also as I mentioned in the other thread, I don't think adding different MACRO value for a kernel version is a long-term maintainable approach. Instead I am working on adding a similar functionality as present in makedumpfile to make the PAGE_OFFSET calculation generic. Only if we fail to calculate PAGE_OFFSET through a generic method should we fall back on MACRO values for backward compatibility. I will try to post the patch for reviews by tomorrow. [0]. https://lkml.org/lkml/2019/8/28/1060 Thanks, Bhupesh > Without this patch, the file /mnt/crash.vmcore has the wrong vaddr in the elf > headers and can't be processed by gdb or crash. > > With this patch, the file has the correct vaddr an can be processed by gdb > and crash. > > Btw: I've got four strange error replies for my mail. > > Date: 30 Aug 2019 05:13:31 EDT > From: mailer_dae...@email.uscc.net > To: buc...@molgen.mpg.de > Message to 7867650...@email.uscc.net failed. > > I hope, my patch reaches the right people anyway. > > Best > Donald > > > > > > #ifdef __x86_64__ > > #define __PAGE_OFFSET_ORIG (0xffff810000000000) /* 2.6.26, or former */ > > #define __PAGE_OFFSET_2_6_27 (0xffff880000000000) /* 2.6.27, or later */ > > #define __PAGE_OFFSET_5LEVEL (0xff10000000000000) /* 5-level page table > > */ > > ... > > #endif > > > > Thanks > > Baoquan > > > >> > >> Update to new address accordingly. > >> --- > >> kexec/arch/i386/crashdump-x86.c | 2 ++ > >> kexec/arch/i386/crashdump-x86.h | 3 ++- > >> 2 files changed, 4 insertions(+), 1 deletion(-) > >> > >> diff --git a/kexec/arch/i386/crashdump-x86.c > >> b/kexec/arch/i386/crashdump-x86.c > >> index a2aea31..c79791f 100644 > >> --- a/kexec/arch/i386/crashdump-x86.c > >> +++ b/kexec/arch/i386/crashdump-x86.c > >> @@ -61,6 +61,8 @@ static int get_kernel_page_offset(struct kexec_info > >> *UNUSED(info), > >> > >> if (kv < KERNEL_VERSION(2, 6, 27)) > >> elf_info->page_offset = X86_64_PAGE_OFFSET_PRE_2_6_27; > >> + else if (kv < KERNEL_VERSION(4, 20, 0)) > >> + elf_info->page_offset = X86_64_PAGE_OFFSET_PRE_4_20_0; > >> else > >> elf_info->page_offset = X86_64_PAGE_OFFSET; > >> } > >> diff --git a/kexec/arch/i386/crashdump-x86.h > >> b/kexec/arch/i386/crashdump-x86.h > >> index ddee19f..e4fdc82 100644 > >> --- a/kexec/arch/i386/crashdump-x86.h > >> +++ b/kexec/arch/i386/crashdump-x86.h > >> @@ -13,7 +13,8 @@ int load_crashdump_segments(struct kexec_info *info, > >> char *mod_cmdline, > >> > >> #define X86_64__START_KERNEL_map 0xffffffff80000000ULL > >> #define X86_64_PAGE_OFFSET_PRE_2_6_27 0xffff810000000000ULL > >> -#define X86_64_PAGE_OFFSET 0xffff880000000000ULL > >> +#define X86_64_PAGE_OFFSET_PRE_4_20_0 0xffff880000000000ULL > >> +#define X86_64_PAGE_OFFSET 0xffff888000000000ULL > >> > >> #define X86_64_MAXMEM 0x3fffffffffffUL > >> > >> -- > >> 2.22.0 > >> > >> > >> _______________________________________________ > >> kexec mailing list > >> kexec@lists.infradead.org > >> http://lists.infradead.org/mailman/listinfo/kexec > > > -- > Donald Buczek > buc...@molgen.mpg.de > Tel: +49 30 8413 1433 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec