Motivation: ============= Previously, LKP reported a building error. When investigating, it can't be resolved reasonablly with the present messy kdump config items. https://lore.kernel.org/oe-kbuild-all/202312182200.Ka7MzifQ-lkp@xxxxxxxxx/ The kdump (crash dumping) related config items could causes confusions: Firstly, --- CRASH_CORE enables codes including - crashkernel reservation; - elfcorehdr updating; - vmcoreinfo exporting; - crash hotplug handling; Now fadump of powerpc, kcore dynamic debugging and kdump all selects CRASH_CORE, while fadump - fadump needs crashkernel parsing, vmcoreinfo exporting, and accessing global variable 'elfcorehdr_addr'; - kcore only needs vmcoreinfo exporting; - kdump needs all of the current kernel/crash_core.c. So only enabling PROC_CORE or FA_DUMP will enable CRASH_CORE, this mislead people that we enable crash dumping, actual it's not. Secondly, --- It's not reasonable to allow KEXEC_CORE select CRASH_CORE. Because KEXEC_CORE enables codes which allocate control pages, copy kexec/kdump segments, and prepare for switching. These codes are shared by both kexec reboot and kdump. We could want kexec reboot, but disable kdump. In that case, CRASH_CORE should not be selected. -------------------- CONFIG_CRASH_CORE=y CONFIG_KEXEC_CORE=y CONFIG_KEXEC=y CONFIG_KEXEC_FILE=y --------------------- Thirdly, --- It's not reasonable to allow CRASH_DUMP select KEXEC_CORE. That could make KEXEC_CORE, CRASH_DUMP are enabled independently from KEXEC or KEXEC_FILE. However, w/o KEXEC or KEXEC_FILE, the KEXEC_CORE code built in doesn't make any sense because no kernel loading or switching will happen to utilize the KEXEC_CORE code. --------------------- CONFIG_CRASH_CORE=y CONFIG_KEXEC_CORE=y CONFIG_CRASH_DUMP=y --------------------- In this case, what is worse, on arch sh and arm, KEXEC relies on MMU, while CRASH_DUMP can still be enabled when !MMU, then compiling error is seen as the lkp test robot reported in above link. ------arch/sh/Kconfig------ config ARCH_SUPPORTS_KEXEC def_bool MMU config ARCH_SUPPORTS_CRASH_DUMP def_bool BROKEN_ON_SMP --------------------------- Changes: =========== 1, split out crash_reserve.c from crash_core.c; 2, split out vmcore_infoc. from crash_core.c; 3, move crash related codes in kexec_core.c into crash_core.c; 4, remove dependency of FA_DUMP on CRASH_DUMP; 5, clean up kdump related config items; 6, wrap up crash codes in crash related ifdefs on all 8 arch-es which support crash dumping, except of ppc; Achievement: =========== With above changes, I can rearrange the config item logic as below (the right item depends on or is selected by the left item): PROC_KCORE -----------> VMCORE_INFO |----------> VMCORE_INFO FA_DUMP----| |----------> CRASH_RESERVE ---->VMCORE_INFO / |---->CRASH_RESERVE KEXEC --| /| |--> KEXEC_CORE--> CRASH_DUMP-->/-|---->PROC_VMCORE KEXEC_FILE --| \ | \---->CRASH_HOTPLUG KEXEC --| |--> KEXEC_CORE (for kexec reboot only) KEXEC_FILE --| Test ======== On all 8 architectures, including x86_64, arm64, s390x, sh, arm, mips, riscv, loongarch, I did below three cases of config item setting and building all passed. Take configs on x86_64 as exampmle here: (1) Both CONFIG_KEXEC and KEXEC_FILE is unset, then all kexec/kdump items are unset automatically: # Kexec and crash features # CONFIG_KEXEC is not set # CONFIG_KEXEC_FILE is not set # end of Kexec and crash features (2) set CONFIG_KEXEC_FILE and 'make olddefconfig': --------------- # Kexec and crash features CONFIG_CRASH_RESERVE=y CONFIG_VMCORE_INFO=y CONFIG_KEXEC_CORE=y CONFIG_KEXEC_FILE=y CONFIG_CRASH_DUMP=y CONFIG_CRASH_HOTPLUG=y CONFIG_CRASH_MAX_MEMORY_RANGES=8192 # end of Kexec and crash features --------------- (3) unset CONFIG_CRASH_DUMP in case 2 and execute 'make olddefconfig': ------------------------ # Kexec and crash features CONFIG_KEXEC_CORE=y CONFIG_KEXEC_FILE=y # end of Kexec and crash features ------------------------ Note: For ppc, it needs investigation to make clear how to split out crash code in arch folder. Hope Hari and Pingfan can help have a look, see if it's doable. Now, I make it either have both kexec and crash enabled, or disable both of them altogether. Changelog ========== v2->v3: - In patch 2, there's conflict when rebasing to linux-next in kernel/crash_core.c because of below commits from Uladzislau: - commit 699d9351822e ("mm: vmalloc: Fix a warning in the crash_save_vmcoreinfo_init()") - commit 5f4c0c1e2a51 (:mm/vmalloc: remove vmap_area_list") - In patch 13, fix the lkp reported issue by using CONFIG_CRASH_RESERVE ifdef, giving up the earlier IS_ENABLED(CONFIG_CRASH_RESERVE) checking in v2. - In patch 14, update code change after below commit merged into mainline: - commit 78de91b45860 ("LoongArch: Use generic interface to support crashkernel=X,[high,low]") Baoquan He (14): kexec: split crashkernel reservation code out from crash_core.c crash: split vmcoreinfo exporting code out from crash_core.c crash: remove dependency of FA_DUMP on CRASH_DUMP crash: split crash dumping code out from kexec_core.c crash: clean up kdump related config items x86, crash: wrap crash dumping code into crash related ifdefs arm64, crash: wrap crash dumping code into crash related ifdefs ppc, crash: enforce KEXEC and KEXEC_FILE to select CRASH_DUMP s390, crash: wrap crash dumping code into crash related ifdefs sh, crash: wrap crash dumping code into crash related ifdefs mips, crash: wrap crash dumping code into crash related ifdefs riscv, crash: wrap crash dumping code into crash related ifdefs arm, crash: wrap crash dumping code into crash related ifdefs loongarch, crash: wrap crash dumping code into crash related ifdefs arch/arm/kernel/setup.c | 4 +- arch/arm64/Kconfig | 2 +- .../asm/{crash_core.h => crash_reserve.h} | 4 +- arch/arm64/include/asm/kexec.h | 2 +- arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/machine_kexec.c | 2 +- arch/arm64/kernel/machine_kexec_file.c | 10 +- .../kernel/{crash_core.c => vmcore_info.c} | 2 +- arch/arm64/mm/init.c | 2 +- arch/loongarch/kernel/setup.c | 2 +- arch/mips/kernel/setup.c | 17 +- arch/powerpc/Kconfig | 9 +- arch/powerpc/kernel/setup-common.c | 2 +- arch/powerpc/mm/nohash/kaslr_booke.c | 4 +- arch/powerpc/platforms/powernv/opal-core.c | 2 +- arch/riscv/Kconfig | 2 +- .../asm/{crash_core.h => crash_reserve.h} | 4 +- arch/riscv/kernel/Makefile | 2 +- arch/riscv/kernel/elf_kexec.c | 9 +- .../kernel/{crash_core.c => vmcore_info.c} | 2 +- arch/riscv/mm/init.c | 2 +- arch/s390/kernel/kexec_elf.c | 2 + arch/s390/kernel/kexec_image.c | 2 + arch/s390/kernel/machine_kexec_file.c | 10 + arch/sh/kernel/machine_kexec.c | 3 + arch/sh/kernel/setup.c | 2 +- arch/x86/Kconfig | 2 +- .../asm/{crash_core.h => crash_reserve.h} | 6 +- arch/x86/kernel/Makefile | 6 +- arch/x86/kernel/cpu/mshyperv.c | 4 + arch/x86/kernel/kexec-bzimage64.c | 4 + arch/x86/kernel/kvm.c | 4 +- arch/x86/kernel/machine_kexec_64.c | 3 + arch/x86/kernel/reboot.c | 2 +- arch/x86/kernel/setup.c | 2 +- arch/x86/kernel/smp.c | 2 +- .../{crash_core_32.c => vmcore_info_32.c} | 2 +- .../{crash_core_64.c => vmcore_info_64.c} | 2 +- arch/x86/xen/enlighten_hvm.c | 4 + drivers/base/cpu.c | 6 +- drivers/firmware/qemu_fw_cfg.c | 14 +- fs/proc/Kconfig | 2 +- fs/proc/kcore.c | 2 +- include/linux/buildid.h | 2 +- include/linux/crash_core.h | 152 ++-- include/linux/crash_reserve.h | 48 ++ include/linux/kexec.h | 47 +- include/linux/vmcore_info.h | 81 ++ init/initramfs.c | 2 +- kernel/Kconfig.kexec | 12 +- kernel/Makefile | 5 +- kernel/crash_core.c | 762 +++++------------- kernel/crash_reserve.c | 464 +++++++++++ kernel/{crash_dump.c => elfcorehdr.c} | 0 kernel/kexec.c | 11 +- kernel/kexec_core.c | 250 +----- kernel/kexec_file.c | 13 +- kernel/kexec_internal.h | 2 + kernel/ksysfs.c | 10 +- kernel/printk/printk.c | 4 +- kernel/vmcore_info.c | 231 ++++++ lib/buildid.c | 2 +- 62 files changed, 1228 insertions(+), 1043 deletions(-) rename arch/arm64/include/asm/{crash_core.h => crash_reserve.h} (81%) rename arch/arm64/kernel/{crash_core.c => vmcore_info.c} (97%) rename arch/riscv/include/asm/{crash_core.h => crash_reserve.h} (78%) rename arch/riscv/kernel/{crash_core.c => vmcore_info.c} (96%) rename arch/x86/include/asm/{crash_core.h => crash_reserve.h} (92%) rename arch/x86/kernel/{crash_core_32.c => vmcore_info_32.c} (90%) rename arch/x86/kernel/{crash_core_64.c => vmcore_info_64.c} (94%) create mode 100644 include/linux/crash_reserve.h create mode 100644 include/linux/vmcore_info.h create mode 100644 kernel/crash_reserve.c rename kernel/{crash_dump.c => elfcorehdr.c} (100%) create mode 100644 kernel/vmcore_info.c -- 2.41.0
