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authorEric DeVolder <eric.devolder@oracle.com>2023-08-15 00:44:40 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-08-25 02:25:13 +0300
commit24726275612140af6b1c0afc7c6611ad66233207 (patch)
treed5f9a91d7bdae1320120213d4f8940f4403b9a74 /include/linux/kexec.h
parent6f991cc363a3269866476b8ff10a112768d3d45c (diff)
downloadlinux-24726275612140af6b1c0afc7c6611ad66233207.tar.xz
crash: add generic infrastructure for crash hotplug support
To support crash hotplug, a mechanism is needed to update the crash elfcorehdr upon CPU or memory changes (eg. hot un/plug or off/ onlining). The crash elfcorehdr describes the CPUs and memory to be written into the vmcore. To track CPU changes, callbacks are registered with the cpuhp mechanism via cpuhp_setup_state_nocalls(CPUHP_BP_PREPARE_DYN). The crash hotplug elfcorehdr update has no explicit ordering requirement (relative to other cpuhp states), so meets the criteria for utilizing CPUHP_BP_PREPARE_DYN. CPUHP_BP_PREPARE_DYN is a dynamic state and avoids the need to introduce a new state for crash hotplug. Also, CPUHP_BP_PREPARE_DYN is the last state in the PREPARE group, just prior to the STARTING group, which is very close to the CPU starting up in a plug/online situation, or stopping in a unplug/ offline situation. This minimizes the window of time during an actual plug/online or unplug/offline situation in which the elfcorehdr would be inaccurate. Note that for a CPU being unplugged or offlined, the CPU will still be present in the list of CPUs generated by crash_prepare_elf64_headers(). However, there is no need to explicitly omit the CPU, see justification in 'crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()'. To track memory changes, a notifier is registered to capture the memblock MEM_ONLINE and MEM_OFFLINE events via register_memory_notifier(). The CPU callbacks and memory notifiers invoke crash_handle_hotplug_event() which performs needed tasks and then dispatches the event to the architecture specific arch_crash_handle_hotplug_event() to update the elfcorehdr with the current state of CPUs and memory. During the process, the kexec_lock is held. Link: https://lkml.kernel.org/r/20230814214446.6659-3-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>
Diffstat (limited to 'include/linux/kexec.h')
-rw-r--r--include/linux/kexec.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index fb4350db33ff..df395f888915 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -33,6 +33,7 @@ extern note_buf_t __percpu *crash_notes;
#include <linux/compat.h>
#include <linux/ioport.h>
#include <linux/module.h>
+#include <linux/highmem.h>
#include <asm/kexec.h>
/* Verify architecture specific macros are defined */
@@ -345,6 +346,12 @@ struct kimage {
struct purgatory_info purgatory_info;
#endif
+#ifdef CONFIG_CRASH_HOTPLUG
+ int hp_action;
+ int elfcorehdr_index;
+ bool elfcorehdr_updated;
+#endif
+
#ifdef CONFIG_IMA_KEXEC
/* Virtual address of IMA measurement buffer for kexec syscall */
void *ima_buffer;
@@ -475,6 +482,10 @@ static inline int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, g
static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { }
#endif
+#ifndef arch_crash_handle_hotplug_event
+static inline void arch_crash_handle_hotplug_event(struct kimage *image) { }
+#endif
+
#else /* !CONFIG_KEXEC_CORE */
struct pt_regs;
struct task_struct;