CPU and memory change notifications are received in order to regenerate the elfcorehdr.
To support cpu hotplug, a callback is registered to capture the CPUHP_AP_ONLINE_DYN online and offline events via cpuhp_setup_state_nocalls(). To support memory hotplug, a notifier is registered to capture the MEM_ONLINE and MEM_OFFLINE events via register_memory_notifier(). The cpu callback and memory notifiers call handle_hotplug_event() which performs needed tasks and then dispatches the event to the architecture specific arch_crash_handle_hotplug_event(). During the process, the kexec_mutex is held. Signed-off-by: Eric DeVolder <[email protected]> --- include/linux/crash_core.h | 24 ++++++++ include/linux/kexec.h | 7 +++ kernel/crash_core.c | 118 +++++++++++++++++++++++++++++++++++++ 3 files changed, 149 insertions(+) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index cb0f1916fbf5..c9705b6872e7 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -86,4 +86,28 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram, int parse_crashkernel_low(char *cmdline, unsigned long long system_ram, unsigned long long *crash_size, unsigned long long *crash_base); +#define KEXEC_CRASH_HP_REMOVE_CPU 0 +#define KEXEC_CRASH_HP_ADD_CPU 1 +#define KEXEC_CRASH_HP_REMOVE_MEMORY 2 +#define KEXEC_CRASH_HP_ADD_MEMORY 3 +#define KEXEC_CRASH_HP_INVALID_CPU -1U + +struct kimage; +#ifndef arch_map_crash_pages +static inline void *arch_map_crash_pages(unsigned long paddr, + unsigned long size) +{ + return NULL; +} +#endif +#ifndef arch_unmap_crash_pages +static inline void arch_unmap_crash_pages(void **ptr) { } +#endif +#ifndef arch_crash_handle_hotplug_event +static inline void arch_crash_handle_hotplug_event(struct kimage *image, + unsigned int hp_action, unsigned int cpu) +{ +} +#endif + #endif /* LINUX_CRASH_CORE_H */ diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 5f4969cf3f4e..7694aa77b92b 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -340,6 +340,13 @@ struct kimage { struct purgatory_info purgatory_info; #endif +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) + bool hotplug_event; + unsigned int offlinecpu; + bool elfcorehdr_index_valid; + int elfcorehdr_index; +#endif + #ifdef CONFIG_IMA_KEXEC /* Virtual address of IMA measurement buffer for kexec syscall */ void *ima_buffer; diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 212d4dad0ec7..154ef532d45a 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -10,12 +10,16 @@ #include <linux/utsname.h> #include <linux/vmalloc.h> #include <linux/kexec.h> +#include <linux/memory.h> +#include <linux/cpuhotplug.h> #include <asm/page.h> #include <asm/sections.h> #include <crypto/sha1.h> +#include "kexec_internal.h" + /* vmcoreinfo stuff */ unsigned char *vmcoreinfo_data; size_t vmcoreinfo_size; @@ -587,3 +591,117 @@ static int __init crash_save_vmcoreinfo_init(void) } subsys_initcall(crash_save_vmcoreinfo_init); + +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) +static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu) +{ + /* Obtain lock while changing crash information */ + mutex_lock(&kexec_mutex); + + /* Check kdump is loaded */ + if (kexec_crash_image) { + struct kimage *image = kexec_crash_image; + + pr_debug("crash hp: hp_action %u, cpu %u", hp_action, cpu); + + /* + * When the struct kimage is alloced, it is wiped to zero, so + * the elfcorehdr_index_valid defaults to false. Find the + * segment containing the elfcorehdr, if not already found. + * This works for both the kexec_load and kexec_file_load paths. + */ + if (!image->elfcorehdr_index_valid) { + unsigned char *ptr; + unsigned long mem, memsz; + unsigned int n; + + for (n = 0; n < image->nr_segments; n++) { + mem = image->segment[n].mem; + memsz = image->segment[n].memsz; + ptr = arch_map_crash_pages(mem, memsz); + if (ptr) { + /* The segment containing elfcorehdr */ + if (memcmp(ptr, ELFMAG, SELFMAG) == 0) { + image->elfcorehdr_index = (int)n; + image->elfcorehdr_index_valid = true; + } + } + arch_unmap_crash_pages((void **)&ptr); + } + } + + if (!image->elfcorehdr_index_valid) { + pr_err("crash hp: unable to locate elfcorehdr segment"); + goto out; + } + + /* Needed in order for the segments to be updated */ + arch_kexec_unprotect_crashkres(); + + /* Flag to differentiate between normal load and hotplug */ + image->hotplug_event = true; + + /* Now invoke arch-specific update handler */ + arch_crash_handle_hotplug_event(image, hp_action, cpu); + + /* No longer handling a hotplug event */ + image->hotplug_event = false; + + /* Change back to read-only */ + arch_kexec_protect_crashkres(); + } + +out: + /* Release lock now that update complete */ + mutex_unlock(&kexec_mutex); +} + +static int crash_memhp_notifier(struct notifier_block *nb, unsigned long val, void *v) +{ + switch (val) { + case MEM_ONLINE: + handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY, 0); + break; + + case MEM_OFFLINE: + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, 0); + break; + } + return NOTIFY_OK; +} + +static struct notifier_block crash_memhp_nb = { + .notifier_call = crash_memhp_notifier, + .priority = 0 +}; + +static int crash_cpuhp_online(unsigned int cpu) +{ + handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu); + return 0; +} + +static int crash_cpuhp_offline(unsigned int cpu) +{ + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu); + return 0; +} + +static int __init crash_hotplug_init(void) +{ + int result = 0; + + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) + register_memory_notifier(&crash_memhp_nb); + + if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) + result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "crash/cpuhp", + crash_cpuhp_online, + crash_cpuhp_offline); + + return result; +} + +subsys_initcall(crash_hotplug_init); +#endif -- 2.31.1 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
