Messages in this thread | | | Subject | Re: [RESEND PATCH v5 00/11] ppc64: enable kdump support for kexec_file_load syscall | From | Hari Bathini <> | Date | Thu, 30 Jul 2020 11:35:07 +0530 |
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On 28/07/20 8:02 am, piliu wrote: > > > On 07/27/2020 03:36 AM, Hari Bathini wrote: >> Sorry! There was a gateway issue on my system while posting v5, due to >> which some patches did not make it through. Resending... >> >> This patch series enables kdump support for kexec_file_load system >> call (kexec -s -p) on PPC64. The changes are inspired from kexec-tools >> code but heavily modified for kernel consumption. >> >> The first patch adds a weak arch_kexec_locate_mem_hole() function to >> override locate memory hole logic suiting arch needs. There are some >> special regions in ppc64 which should be avoided while loading buffer >> & there are multiple callers to kexec_add_buffer making it complicated >> to maintain range sanity and using generic lookup at the same time. >> >> The second patch marks ppc64 specific code within arch/powerpc/kexec >> and arch/powerpc/purgatory to make the subsequent code changes easy >> to understand. >> >> The next patch adds helper function to setup different memory ranges >> needed for loading kdump kernel, booting into it and exporting the >> crashing kernel's elfcore. >> >> The fourth patch overrides arch_kexec_locate_mem_hole() function to >> locate memory hole for kdump segments by accounting for the special >> memory regions, referred to as excluded memory ranges, and sets >> kbuf->mem when a suitable memory region is found. >> >> The fifth patch moves walk_drmem_lmbs() out of .init section with >> a few changes to reuse it for setting up kdump kernel's usable memory >> ranges. The next patch uses walk_drmem_lmbs() to look up the LMBs >> and set linux,drconf-usable-memory & linux,usable-memory properties >> in order to restrict kdump kernel's memory usage. >> >> The seventh patch updates purgatory to setup r8 & r9 with opal base >> and opal entry addresses respectively to aid kernels built with >> CONFIG_PPC_EARLY_DEBUG_OPAL enabled. The next patch setups up backup >> region as a kexec segment while loading kdump kernel and teaches >> purgatory to copy data from source to destination. >> >> Patch 09 builds the elfcore header for the running kernel & passes >> the info to kdump kernel via "elfcorehdr=" parameter to export as >> /proc/vmcore file. The next patch sets up the memory reserve map >> for the kexec kernel and also claims kdump support for kdump as >> all the necessary changes are added. >> >> The last patch fixes a lookup issue for `kexec -l -s` case when >> memory is reserved for crashkernel. >> >> Tested the changes successfully on P8, P9 lpars, couple of OpenPOWER >> boxes, one with secureboot enabled, KVM guest and a simulator. >> >> v4 -> v5: >> * Dropped patches 07/12 & 08/12 and updated purgatory to do everything >> in assembly.
Hello Pingfan,
Sorry, I missed out on responding to this.
> I guess you achieve this by carefully selecting instruction to avoid > relocation issue, right?
Yes. No far branching or reference to data from elsewhere.
Thanks Hari
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