From: Eric DeVolder <eric.devolder@oracle.com> To: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, eric.devolder@oracle.com Subject: [PATCH v16 3/7] crash: add generic infrastructure for crash hotplug support Date: Thu, 5 Jan 2023 10:17:05 -0500 [thread overview] Message-ID: <20230105151709.1845-4-eric.devolder@oracle.com> (raw) In-Reply-To: <20230105151709.1845-1-eric.devolder@oracle.com> 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_lock is held. Signed-off-by: Eric DeVolder <eric.devolder@oracle.com> Acked-by: Baoquan He <bhe@redhat.com> --- include/linux/crash_core.h | 8 +++ include/linux/kexec.h | 12 ++++ kernel/crash_core.c | 138 +++++++++++++++++++++++++++++++++++++ 3 files changed, 158 insertions(+) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index de62a722431e..a270f8660538 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -84,4 +84,12 @@ 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; + #endif /* LINUX_CRASH_CORE_H */ diff --git a/include/linux/kexec.h b/include/linux/kexec.h index c8662a48d455..a1838699d7b2 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 */ @@ -371,6 +372,13 @@ struct kimage { struct purgatory_info purgatory_info; #endif +#ifdef CONFIG_CRASH_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; @@ -500,6 +508,10 @@ 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; diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 92eb7dc05457..973d7ddff1cf 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -11,6 +11,8 @@ #include <linux/vmalloc.h> #include <linux/sizes.h> #include <linux/kexec.h> +#include <linux/memory.h> +#include <linux/cpuhotplug.h> #include <asm/page.h> #include <asm/sections.h> @@ -18,6 +20,7 @@ #include <crypto/sha1.h> #include "kallsyms_internal.h" +#include "kexec_internal.h" /* vmcoreinfo stuff */ unsigned char *vmcoreinfo_data; @@ -615,3 +618,138 @@ static int __init crash_save_vmcoreinfo_init(void) } subsys_initcall(crash_save_vmcoreinfo_init); + +#ifdef CONFIG_CRASH_HOTPLUG +#undef pr_fmt +#define pr_fmt(fmt) "crash hp: " fmt +/* + * To accurately reflect hot un/plug changes, the elfcorehdr (which + * is passed to the crash kernel via the elfcorehdr= parameter) + * must be updated with the new list of CPUs and memories. + * + * In order to make changes to elfcorehdr, two conditions are needed: + * First, the segment containing the elfcorehdr must be large enough + * to permit a growing number of resources; the elfcorehdr memory size + * is based on NR_CPUS_DEFAULT and CRASH_MAX_MEMORY_RANGES. + * Second, purgatory must explicitly exclude the elfcorehdr from the + * list of segments it checks (since the elfcorehdr changes and thus + * would require an update to purgatory itself to update the digest). + */ +static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu) +{ + /* Obtain lock while changing crash information */ + if (kexec_trylock()) { + + /* Check kdump is loaded */ + if (kexec_crash_image) { + struct kimage *image = kexec_crash_image; + + if (hp_action == KEXEC_CRASH_HP_ADD_CPU || + hp_action == KEXEC_CRASH_HP_REMOVE_CPU) + pr_debug("hp_action %u, cpu %u\n", hp_action, cpu); + else + pr_debug("hp_action %u\n", hp_action); + + /* + * When the struct kimage is allocated, 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 long mem; + unsigned char *ptr; + unsigned int n; + + for (n = 0; n < image->nr_segments; n++) { + mem = image->segment[n].mem; + ptr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); + if (ptr) { + /* The segment containing elfcorehdr */ + if (memcmp(ptr, ELFMAG, SELFMAG) == 0) { + image->elfcorehdr_index = (int)n; + image->elfcorehdr_index_valid = true; + } + kunmap_local(ptr); + } + } + } + + if (!image->elfcorehdr_index_valid) { + pr_err("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); + + /* 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 */ + kexec_unlock(); + } +} + +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, + KEXEC_CRASH_HP_INVALID_CPU); + break; + + case MEM_OFFLINE: + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, + KEXEC_CRASH_HP_INVALID_CPU); + 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
WARNING: multiple messages have this Message-ID (diff)
From: Eric DeVolder <eric.devolder@oracle.com> To: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, eric.devolder@oracle.com Subject: [PATCH v16 3/7] crash: add generic infrastructure for crash hotplug support Date: Thu, 5 Jan 2023 10:17:05 -0500 [thread overview] Message-ID: <20230105151709.1845-4-eric.devolder@oracle.com> (raw) In-Reply-To: <20230105151709.1845-1-eric.devolder@oracle.com> 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_lock is held. Signed-off-by: Eric DeVolder <eric.devolder@oracle.com> Acked-by: Baoquan He <bhe@redhat.com> --- include/linux/crash_core.h | 8 +++ include/linux/kexec.h | 12 ++++ kernel/crash_core.c | 138 +++++++++++++++++++++++++++++++++++++ 3 files changed, 158 insertions(+) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index de62a722431e..a270f8660538 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -84,4 +84,12 @@ 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; + #endif /* LINUX_CRASH_CORE_H */ diff --git a/include/linux/kexec.h b/include/linux/kexec.h index c8662a48d455..a1838699d7b2 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 */ @@ -371,6 +372,13 @@ struct kimage { struct purgatory_info purgatory_info; #endif +#ifdef CONFIG_CRASH_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; @@ -500,6 +508,10 @@ 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; diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 92eb7dc05457..973d7ddff1cf 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -11,6 +11,8 @@ #include <linux/vmalloc.h> #include <linux/sizes.h> #include <linux/kexec.h> +#include <linux/memory.h> +#include <linux/cpuhotplug.h> #include <asm/page.h> #include <asm/sections.h> @@ -18,6 +20,7 @@ #include <crypto/sha1.h> #include "kallsyms_internal.h" +#include "kexec_internal.h" /* vmcoreinfo stuff */ unsigned char *vmcoreinfo_data; @@ -615,3 +618,138 @@ static int __init crash_save_vmcoreinfo_init(void) } subsys_initcall(crash_save_vmcoreinfo_init); + +#ifdef CONFIG_CRASH_HOTPLUG +#undef pr_fmt +#define pr_fmt(fmt) "crash hp: " fmt +/* + * To accurately reflect hot un/plug changes, the elfcorehdr (which + * is passed to the crash kernel via the elfcorehdr= parameter) + * must be updated with the new list of CPUs and memories. + * + * In order to make changes to elfcorehdr, two conditions are needed: + * First, the segment containing the elfcorehdr must be large enough + * to permit a growing number of resources; the elfcorehdr memory size + * is based on NR_CPUS_DEFAULT and CRASH_MAX_MEMORY_RANGES. + * Second, purgatory must explicitly exclude the elfcorehdr from the + * list of segments it checks (since the elfcorehdr changes and thus + * would require an update to purgatory itself to update the digest). + */ +static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu) +{ + /* Obtain lock while changing crash information */ + if (kexec_trylock()) { + + /* Check kdump is loaded */ + if (kexec_crash_image) { + struct kimage *image = kexec_crash_image; + + if (hp_action == KEXEC_CRASH_HP_ADD_CPU || + hp_action == KEXEC_CRASH_HP_REMOVE_CPU) + pr_debug("hp_action %u, cpu %u\n", hp_action, cpu); + else + pr_debug("hp_action %u\n", hp_action); + + /* + * When the struct kimage is allocated, 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 long mem; + unsigned char *ptr; + unsigned int n; + + for (n = 0; n < image->nr_segments; n++) { + mem = image->segment[n].mem; + ptr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); + if (ptr) { + /* The segment containing elfcorehdr */ + if (memcmp(ptr, ELFMAG, SELFMAG) == 0) { + image->elfcorehdr_index = (int)n; + image->elfcorehdr_index_valid = true; + } + kunmap_local(ptr); + } + } + } + + if (!image->elfcorehdr_index_valid) { + pr_err("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); + + /* 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 */ + kexec_unlock(); + } +} + +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, + KEXEC_CRASH_HP_INVALID_CPU); + break; + + case MEM_OFFLINE: + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, + KEXEC_CRASH_HP_INVALID_CPU); + 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 kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2023-01-05 15:18 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-01-05 15:17 [PATCH v16 0/7] crash: Kernel handling of CPU and memory hot un/plug Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-05 15:17 ` [PATCH v16 1/7] crash: move crash_prepare_elf64_headers() Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-05 15:17 ` [PATCH v16 2/7] crash: prototype change for crash_prepare_elf64_headers() Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder [this message] 2023-01-05 15:17 ` [PATCH v16 3/7] crash: add generic infrastructure for crash hotplug support Eric DeVolder 2023-01-05 15:17 ` [PATCH v16 4/7] kexec: exclude elfcorehdr from the segment digest Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-05 15:17 ` [PATCH v16 5/7] kexec: exclude hot remove cpu from elfcorehdr notes Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-05 15:17 ` [PATCH v16 6/7] crash: memory and cpu hotplug sysfs attributes Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-05 15:17 ` [PATCH v16 7/7] x86/crash: add x86 crash hotplug support Eric DeVolder 2023-01-05 15:17 ` Eric DeVolder 2023-01-09 7:36 ` Baoquan He 2023-01-09 7:36 ` Baoquan He 2023-01-09 19:43 ` Eric DeVolder 2023-01-09 19:43 ` Eric DeVolder 2023-01-09 23:47 ` Baoquan He 2023-01-09 23:47 ` Baoquan He
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