Hi Prabhakar, On Wed, Nov 27, 2019 at 10:20 AM Prabhakar Kushwaha <prabhakar.pkin@xxxxxxxxx> wrote: > > Thanks Bhupesh for replying > > On Wed, Nov 27, 2019 at 2:42 AM Bhupesh Sharma <bhsharma@xxxxxxxxxx> wrote: > > > > Hi Prabhakar, > > > > On Tue, Nov 26, 2019 at 1:04 PM Prabhakar Kushwaha > > <prabhakar.pkin@xxxxxxxxx> wrote: > > > > > > Hi All, > > > > > > I am facing issue below error with latest kexec-tools/vmcore-demsg tools. > > > > > > $ ./build/sbin/vmcore-dmesg /proc/vmcore > > > No program header covering vaddr 0xffff000be7a00000found kexec bug? > > > > > > I am testing on AARM64 platform with following git repos. > > > A) kexec tools: > > > https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git > > > top commit: bd077966e2b9041c (kexec-tools: Fix conversion overflow > > > when compiling on 32-bit platforms) > > > > > > B) Linux:git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > > > top commit: af42d3466bdc8f3980 (Linux 5.4-rc8) > > > > > > I am seeing similar issue in past also in couple of discussions. has > > > it not fixed earlier or it keep arises with time to time > > > > > > Please suggest. > > > > Thanks for reporting the issue. > > I think the issue with the latest ARM64 kernel and kexec-tools is the > > same as the makedumpfile, i.e. the PAGE_OFFSET calculation needs to be > > dynamically done for 52-bit VA_BITS correctly as well. > > > > Yes we need dynamic approach of calculating VA_BITS. > > Please note, the AARM64 platform used by us is 48Bit. > CONFIG_ARM64_VA_BITS_48=y > CONFIG_ARM64_VA_BITS=48 > CONFIG_ARM64_PA_BITS_48=y > CONFIG_ARM64_PA_BITS=48 > > As per my understanding, this issue is not because of 52 bit. It is > due to patch 14c127c957c1 ("arm64: mm: Flip kernel VA space") in > Linux. > i.e. PAGE_OFFSET address has been moved to bottom instead of middle in > kernel virtual address space. Well the changes for flipping the kernel VA space on arm64 was need for introducing the 52-bit VA address space. You can look at Steve Capper's 53-bit patchset for details which was finally merged in the mainline [of which 14c127c957c1 ("arm64: mm: Flip kernel VA space") is a part]: > As below changes solves mentioned kexec-tools/vmcore-demsg problem. > > diff --git a/kexec/arch/arm64/crashdump-arm64.c > b/kexec/arch/arm64/crashdump-arm64.c > index 4fd7aa8..1c28b06 100644 > --- a/kexec/arch/arm64/crashdump-arm64.c > +++ b/kexec/arch/arm64/crashdump-arm64.c > @@ -58,6 +58,8 @@ static uint64_t get_kernel_page_offset(void) > { > int i; > > + return 0xffff000000000000; --> PAGE_OFFSET Yes, you are hardcoding the PAGE_OFFSET as 0xffff000000000000 for a vabits_actual value of 48-bits and it will work fine on platforms which don't support ARMv8.2 LVA extensions (i.e. ARM v8.2), however on real ARMv8.2 hardware the PAGE_OFFSET value should be 0xfff0000000000000 (for vabits_actual value of 52 bits). See '52-bit VA support in the kernel' section in <https://www.kernel.org/doc/Documentation/arm64/memory.rst> for details. I think I have found a more generic solution to the issue, but I still need to verify on the ARMv8 simulator model (as I need to test othe same on 52-bit platforms as well). Regards, Bhupesh > if (elf_info.kern_vaddr_start == UINT64_MAX) > return UINT64_MAX; > > Also, I verified by moving one patch below 14c127c957c1 in Linux, no > changes required in kexect-tools. Everything works fine. > > The calculation used in makedumpfile (your patches), indirectly takes > care of this. So we need similar calculation here in kexec also. > > > > --pk > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
