| Message ID | 20240124051254.67105-1-bhe@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Split crash out from kexec and clean up related config items | expand |
Hi Baoquan, On Wed, Jan 24, 2024 at 01:12:40PM +0800, Baoquan He wrote: > 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@intel.com/ > > 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. I am seeing a few build failures in my test matrix on next-20240125 that appear to be caused by this series although I have not bisected. Some reproduction steps: $ curl -LSso .config https://git.alpinelinux.org/aports/plain/community/linux-edge/config-edge.armv7 $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- olddefconfig all ... arm-linux-gnueabi-ld: arch/arm/kernel/machine_kexec.o: in function `arch_crash_save_vmcoreinfo': machine_kexec.c:(.text+0x488): undefined reference to `vmcoreinfo_append_str' ... $ curl -LSso .config https://github.com/archlinuxarm/PKGBUILDs/raw/master/core/linux-aarch64/config $ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux- olddefconfig all ... aarch64-linux-ld: kernel/kexec_file.o: in function `kexec_walk_memblock.constprop.0': kexec_file.c:(.text+0x314): undefined reference to `crashk_res' aarch64-linux-ld: kernel/kexec_file.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `crashk_res' which may bind externally can not be used when making a shared object; recompile with -fPIC kexec_file.c:(.text+0x314): dangerous relocation: unsupported relocation aarch64-linux-ld: kexec_file.c:(.text+0x318): undefined reference to `crashk_res' aarch64-linux-ld: drivers/of/kexec.o: in function `of_kexec_alloc_and_setup_fdt': kexec.c:(.text+0x580): undefined reference to `crashk_res' aarch64-linux-ld: drivers/of/kexec.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `crashk_res' which may bind externally can not be used when making a shared object; recompile with -fPIC kexec.c:(.text+0x580): dangerous relocation: unsupported relocation aarch64-linux-ld: kexec.c:(.text+0x584): undefined reference to `crashk_res' aarch64-linux-ld: kexec.c:(.text+0x590): undefined reference to `crashk_res' aarch64-linux-ld: kexec.c:(.text+0x5b0): undefined reference to `crashk_low_res' aarch64-linux-ld: drivers/of/kexec.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `crashk_low_res' which may bind externally can not be used when making a shared object; recompile with -fPIC kexec.c:(.text+0x5b0): dangerous relocation: unsupported relocation aarch64-linux-ld: kexec.c:(.text+0x5b4): undefined reference to `crashk_low_res' aarch64-linux-ld: kexec.c:(.text+0x5c0): undefined reference to `crashk_low_res' ... $ curl -LSso .config https://git.alpinelinux.org/aports/plain/community/linux-edge/config-edge.x86_64 $ make -skj"$(nproc)" ARCH=x86_64 CROSS_COMPILE=x86_64-linux- olddefconfig all ... x86_64-linux-ld: arch/x86/xen/mmu_pv.o: in function `paddr_vmcoreinfo_note': mmu_pv.c:(.text+0x3af3): undefined reference to `vmcoreinfo_note' ... Cheers, Nathan
On 01/25/24 at 09:55pm, Nathan Chancellor wrote: ...... > I am seeing a few build failures in my test matrix on next-20240125 that > appear to be caused by this series although I have not bisected. Some > reproduction steps: Thanks for trying this, I have reproduced the linking failure on arm, will work out a way to fix it. It's weird, I remember I have built these and passed. > > $ curl -LSso .config https://git.alpinelinux.org/aports/plain/community/linux-edge/config-edge.armv7 > $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- olddefconfig all > ... > arm-linux-gnueabi-ld: arch/arm/kernel/machine_kexec.o: in function `arch_crash_save_vmcoreinfo': > machine_kexec.c:(.text+0x488): undefined reference to `vmcoreinfo_append_str' > ... > > $ curl -LSso .config https://github.com/archlinuxarm/PKGBUILDs/raw/master/core/linux-aarch64/config > $ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux- olddefconfig all > ... > aarch64-linux-ld: kernel/kexec_file.o: in function `kexec_walk_memblock.constprop.0': > kexec_file.c:(.text+0x314): undefined reference to `crashk_res' > aarch64-linux-ld: kernel/kexec_file.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `crashk_res' which may bind externally can not be used when making a shared object; recompile with -fPIC > kexec_file.c:(.text+0x314): dangerous relocation: unsupported relocation > aarch64-linux-ld: kexec_file.c:(.text+0x318): undefined reference to `crashk_res' > aarch64-linux-ld: drivers/of/kexec.o: in function `of_kexec_alloc_and_setup_fdt': > kexec.c:(.text+0x580): undefined reference to `crashk_res' > aarch64-linux-ld: drivers/of/kexec.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `crashk_res' which may bind externally can not be used when making a shared object; recompile with -fPIC > kexec.c:(.text+0x580): dangerous relocation: unsupported relocation > aarch64-linux-ld: kexec.c:(.text+0x584): undefined reference to `crashk_res' > aarch64-linux-ld: kexec.c:(.text+0x590): undefined reference to `crashk_res' > aarch64-linux-ld: kexec.c:(.text+0x5b0): undefined reference to `crashk_low_res' > aarch64-linux-ld: drivers/of/kexec.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `crashk_low_res' which may bind externally can not be used when making a shared object; recompile with -fPIC > kexec.c:(.text+0x5b0): dangerous relocation: unsupported relocation > aarch64-linux-ld: kexec.c:(.text+0x5b4): undefined reference to `crashk_low_res' > aarch64-linux-ld: kexec.c:(.text+0x5c0): undefined reference to `crashk_low_res' > ... > > $ curl -LSso .config https://git.alpinelinux.org/aports/plain/community/linux-edge/config-edge.x86_64 > $ make -skj"$(nproc)" ARCH=x86_64 CROSS_COMPILE=x86_64-linux- olddefconfig all > ... > x86_64-linux-ld: arch/x86/xen/mmu_pv.o: in function `paddr_vmcoreinfo_note': > mmu_pv.c:(.text+0x3af3): undefined reference to `vmcoreinfo_note' > ... > > Cheers, > Nathan >
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@intel.com/ 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