When CPU or memory is hot un/plugged, or off/onlined, the crash elfcorehdr, which describes the CPUs and memory in the system, must also be updated.
A new elfcorehdr is generated from the available CPUs and memory and replaces the existing elfcorehdr. The segment containing the elfcorehdr is identified at run-time in crash_core:crash_handle_hotplug_event(). No modifications to purgatory (see 'kexec: exclude elfcorehdr from the segment digest') or boot_params (as the elfcorehdr= capture kernel command line parameter pointer remains unchanged and correct) are needed, just elfcorehdr. For kexec_file_load(), the elfcorehdr segment size is based on NR_CPUS and CRASH_MAX_MEMORY_RANGES in order to accommodate a growing number of CPU and memory resources. For kexec_load(), the userspace kexec utility needs to size the elfcorehdr segment in the same/similar manner. To accommodate kexec_load() syscall in the absence of kexec_file_load() syscall support, prepare_elf_headers() and dependents are moved outside of CONFIG_KEXEC_FILE. Signed-off-by: Eric DeVolder <[email protected]> Reviewed-by: Sourabh Jain <[email protected]> Acked-by: Hari Bathini <[email protected]> Acked-by: Baoquan He <[email protected]> --- arch/x86/Kconfig | 3 + arch/x86/include/asm/kexec.h | 15 +++++ arch/x86/kernel/crash.c | 105 ++++++++++++++++++++++++++++++++--- 3 files changed, 116 insertions(+), 7 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7082fc10b346..ffc95c3d6abd 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2069,6 +2069,9 @@ config ARCH_SUPPORTS_KEXEC_JUMP config ARCH_SUPPORTS_CRASH_DUMP def_bool X86_64 || (X86_32 && HIGHMEM) +config ARCH_SUPPORTS_CRASH_HOTPLUG + def_bool y + config PHYSICAL_START hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) default "0x1000000" diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h index 5b77bbc28f96..9143100ea3ea 100644 --- a/arch/x86/include/asm/kexec.h +++ b/arch/x86/include/asm/kexec.h @@ -209,6 +209,21 @@ typedef void crash_vmclear_fn(void); extern crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss; extern void kdump_nmi_shootdown_cpus(void); +#ifdef CONFIG_CRASH_HOTPLUG +void arch_crash_handle_hotplug_event(struct kimage *image); +#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event + +#ifdef CONFIG_HOTPLUG_CPU +static inline int crash_hotplug_cpu_support(void) { return 1; } +#define crash_hotplug_cpu_support crash_hotplug_cpu_support +#endif + +#ifdef CONFIG_MEMORY_HOTPLUG +static inline int crash_hotplug_memory_support(void) { return 1; } +#define crash_hotplug_memory_support crash_hotplug_memory_support +#endif +#endif + #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_KEXEC_H */ diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index cdd92ab43cda..4b6cebceec68 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -158,8 +158,7 @@ void native_machine_crash_shutdown(struct pt_regs *regs) crash_save_cpu(regs, safe_smp_processor_id()); } -#ifdef CONFIG_KEXEC_FILE - +#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_DUMP) static int get_nr_ram_ranges_callback(struct resource *res, void *arg) { unsigned int *nr_ranges = arg; @@ -231,7 +230,7 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg) /* Prepare elf headers. Return addr and size */ static int prepare_elf_headers(struct kimage *image, void **addr, - unsigned long *sz) + unsigned long *sz, unsigned long *nr_mem_ranges) { struct crash_mem *cmem; int ret; @@ -249,6 +248,9 @@ static int prepare_elf_headers(struct kimage *image, void **addr, if (ret) goto out; + /* Return the computed number of memory ranges, for hotplug usage */ + *nr_mem_ranges = cmem->nr_ranges; + /* By default prepare 64bit headers */ ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz); @@ -256,7 +258,9 @@ static int prepare_elf_headers(struct kimage *image, void **addr, vfree(cmem); return ret; } +#endif +#ifdef CONFIG_KEXEC_FILE static int add_e820_entry(struct boot_params *params, struct e820_entry *entry) { unsigned int nr_e820_entries; @@ -371,18 +375,42 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) int crash_load_segments(struct kimage *image) { int ret; + unsigned long pnum = 0; struct kexec_buf kbuf = { .image = image, .buf_min = 0, .buf_max = ULONG_MAX, .top_down = false }; /* Prepare elf headers and add a segment */ - ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz); + ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz, &pnum); if (ret) return ret; - image->elf_headers = kbuf.buffer; - image->elf_headers_sz = kbuf.bufsz; + image->elf_headers = kbuf.buffer; + image->elf_headers_sz = kbuf.bufsz; + kbuf.memsz = kbuf.bufsz; + +#ifdef CONFIG_CRASH_HOTPLUG + /* + * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map, + * maximum CPUs and maximum memory ranges. + */ + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) + pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES; + else + pnum += 2 + CONFIG_NR_CPUS_DEFAULT; + + if (pnum < (unsigned long)PN_XNUM) { + kbuf.memsz = pnum * sizeof(Elf64_Phdr); + kbuf.memsz += sizeof(Elf64_Ehdr); + + image->elfcorehdr_index = image->nr_segments; + + /* Mark as usable to crash kernel, else crash kernel fails on boot */ + image->elf_headers_sz = kbuf.memsz; + } else { + pr_err("number of Phdrs %lu exceeds max\n", pnum); + } +#endif - kbuf.memsz = kbuf.bufsz; kbuf.buf_align = ELF_CORE_HEADER_ALIGN; kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; ret = kexec_add_buffer(&kbuf); @@ -395,3 +423,66 @@ int crash_load_segments(struct kimage *image) return ret; } #endif /* CONFIG_KEXEC_FILE */ + +#ifdef CONFIG_CRASH_HOTPLUG + +#undef pr_fmt +#define pr_fmt(fmt) "crash hp: " fmt + +/** + * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes + * @image: a pointer to kexec_crash_image + * + * Prepare the new elfcorehdr and replace the existing elfcorehdr. + */ +void arch_crash_handle_hotplug_event(struct kimage *image) +{ + void *elfbuf = NULL, *old_elfcorehdr; + unsigned long nr_mem_ranges; + unsigned long mem, memsz; + unsigned long elfsz = 0; + + /* + * Create the new elfcorehdr reflecting the changes to CPU and/or + * memory resources. + */ + if (prepare_elf_headers(image, &elfbuf, &elfsz, &nr_mem_ranges)) { + pr_err("unable to create new elfcorehdr"); + goto out; + } + + /* + * Obtain address and size of the elfcorehdr segment, and + * check it against the new elfcorehdr buffer. + */ + mem = image->segment[image->elfcorehdr_index].mem; + memsz = image->segment[image->elfcorehdr_index].memsz; + if (elfsz > memsz) { + pr_err("update elfcorehdr elfsz %lu > memsz %lu", + elfsz, memsz); + goto out; + } + + /* + * Copy new elfcorehdr over the old elfcorehdr at destination. + */ + old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); + if (!old_elfcorehdr) { + pr_err("mapping elfcorehdr segment failed\n"); + goto out; + } + + /* + * Temporarily invalidate the crash image while the + * elfcorehdr is updated. + */ + xchg(&kexec_crash_image, NULL); + memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz); + xchg(&kexec_crash_image, image); + kunmap_local(old_elfcorehdr); + pr_debug("updated elfcorehdr\n"); + +out: + vfree(elfbuf); +} +#endif -- 2.31.1 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
