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()
to handle the hot plug/unplug event. Then handle_hotplug_event()
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@xxxxxxxxxx>
---
include/linux/crash_core.h | 10 +++++
include/linux/kexec.h | 5 +++
kernel/crash_core.c | 92 ++++++++++++++++++++++++++++++++++++++
3 files changed, 107 insertions(+)
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index de62a722431e..a240f84348aa 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -84,4 +84,14 @@ 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;
+void arch_crash_handle_hotplug_event(struct kimage *image, unsigned int hp_action,
+ unsigned int cpu);
+
#endif /* LINUX_CRASH_CORE_H */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index f93f2591fc1e..5935bc78ed7f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -308,6 +308,11 @@ struct kimage {
struct purgatory_info purgatory_info;
#endif
+ bool hotplug_event;
+ unsigned int offlinecpu;
+ bool elfcorehdr_index_valid;
+ int elfcorehdr_index;
+
#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 256cf6db573c..f197af50def6 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -9,12 +9,17 @@
#include <linux/init.h>
#include <linux/utsname.h>
#include <linux/vmalloc.h>
+#include <linux/highmem.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;
@@ -491,3 +496,90 @@ static int __init crash_save_vmcoreinfo_init(void)
}
subsys_initcall(crash_save_vmcoreinfo_init);
+
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
+void __weak arch_crash_handle_hotplug_event(struct kimage *image,
+ unsigned int hp_action, unsigned int cpu)
+{
+ WARN(1, "crash hotplug handler not implemented");
+}
+
+static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
+{
+ /* Obtain lock while changing crash information */
+ if (!mutex_trylock(&kexec_mutex))
+ return;
+
+ /* Check kdump is loaded */
+ if (kexec_crash_image) {
+ pr_debug("crash hp: hp_action %u, cpu %u", hp_action, cpu);
+
+ /* Needed in order for the segments to be updated */
+ arch_kexec_unprotect_crashkres();
+
+ /* Flag to differentiate between normal load and hotplug */
+ kexec_crash_image->hotplug_event = true;
+
+ /* Now invoke arch-specific update handler */
+ arch_crash_handle_hotplug_event(kexec_crash_image, hp_action, cpu);
+
+ /* No longer handling a hotplug event */
+ kexec_crash_image->hotplug_event = false;
+
+ /* Change back to read-only */
+ arch_kexec_protect_crashkres();
+ }
+
+ /* 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
--
2.27.0
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