Messages in this thread | | | Date | Mon, 8 Aug 2022 17:30:02 +0800 | From | Baoquan He <> | Subject | Re: [PATCH v10 4/8] crash: add generic infrastructure for crash hotplug support |
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On 07/21/22 at 02:17pm, Eric DeVolder wrote: > 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 <eric.devolder@oracle.com> > --- > 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);
We don't need to check if it's cpu hotplug action here? Then for mem hotplug actions, we also get: "crash hp: hp_action 2, cpu 0" That cpu 0 will be confusing. And you forgot the line break.
Can we do like this: pr_debug("crash hp: hp_action %u ", hp_action); if (hp_action == KEXEC_CRASH_HP_REMOVE_CPU || hp_action == KEXEC_CRASH_HP_REMOVE_CPU) pr_debug("cpu %u \n", cpu);
Other than this, the patch looks good to me.
> + > + /* > + * 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 >
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