On 04/04/23 at 02:03pm, Eric DeVolder wrote:
......
> +static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
> +{
> + struct kimage *image;
> +
> + /* Obtain lock while changing crash information */
> + if (!kexec_trylock()) {
> + pr_info("kexec_trylock() failed, elfcorehdr may be inaccurate\n");
> + return;
> + }
> +
> + /* Check kdump is not loaded */
> + if (!kexec_crash_image)
> + goto out;
> +
> + 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);
Seems we passed in the cpu number just for printing here. Wondering why
we don't print out hot added/removed memory ranges. Is the cpu number
printing necessary?
> +
> + /*
> + * When the struct kimage is allocated, the elfcorehdr_index
> + * is set to -1. 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 < 0) {
> + 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;
> + kunmap_local(ptr);
> + }
> + }
> + }
> +
> + if (image->elfcorehdr_index < 0) {
> + pr_err("unable to locate elfcorehdr segment");
> + goto out;
> + }
> +
> + /* Needed in order for the segments to be updated */
> + arch_kexec_unprotect_crashkres();
> +
> + /* Differentiate between normal load and hotplug update */
> + image->hp_action = hp_action;
> +
> + /* Now invoke arch-specific update handler */
> + arch_crash_handle_hotplug_event(image);
> +
> + /* No longer handling a hotplug event */
> + image->hp_action = KEXEC_CRASH_HP_NONE;
> + image->elfcorehdr_updated = true;
> +
> + /* 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:
> + crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY,
> + KEXEC_CRASH_HP_INVALID_CPU);
> + break;
> +
> + case MEM_OFFLINE:
> + crash_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)
> +{
> + crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu);
> + return 0;
> +}
> +
> +static int crash_cpuhp_offline(unsigned int cpu)
> +{
> + crash_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_BP_PREPARE_DYN,
> + "crash/cpuhp", crash_cpuhp_online, crash_cpuhp_offline);
> + }
> +
> + return result;
> +}
> +
> +subsys_initcall(crash_hotplug_init);
> +#endif
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 3d578c6fefee..8296d019737c 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -277,6 +277,12 @@ struct kimage *do_kimage_alloc_init(void)
> /* Initialize the list of unusable pages */
> INIT_LIST_HEAD(&image->unusable_pages);
>
> +#ifdef CONFIG_CRASH_HOTPLUG
> + image->hp_action = KEXEC_CRASH_HP_NONE;
> + image->elfcorehdr_index = -1;
> + image->elfcorehdr_updated = false;
> +#endif
> +
> return image;
> }
>
> --
> 2.31.1
>
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