diff options
author | Eric DeVolder <eric.devolder@oracle.com> | 2023-08-14 17:44:43 -0400 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-24 16:25:14 -0700 |
commit | ea53ad9cf73b6b48608a69e626caeae87e5ddd11 (patch) | |
tree | 9673c3e8124a8ade6de5becd538c8bee1a85cbe6 | |
parent | 88a6f89944216b028d3872b0cec0f51a2f955460 (diff) |
x86/crash: add x86 crash hotplug support
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.
[eric.devolder@oracle.com: correct unused function build error]
Link: https://lkml.kernel.org/r/20230821182644.2143-1-eric.devolder@oracle.com
Link: https://lkml.kernel.org/r/20230814214446.6659-6-eric.devolder@oracle.com
Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Akhil Raj <lf32.dev@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r-- | arch/x86/Kconfig | 3 | ||||
-rw-r--r-- | arch/x86/include/asm/kexec.h | 15 | ||||
-rw-r--r-- | arch/x86/kernel/crash.c | 105 |
3 files changed, 116 insertions, 7 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index fedc6dddd743..d9fc80b9ef84 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..d755c41a50a7 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_HOTPLUG) 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 @@ out: 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 @@ out: 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 |