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authorMichael Ellerman <mpe@ellerman.id.au>2024-05-13 16:12:08 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2024-05-13 16:12:08 +0300
commite789d4499abdb488dd9cabce4f95c74dac6bcbe5 (patch)
tree86b6c4d7810bcbd2b19a23e332eca0e38ca9df7b /include
parent6d4e52f899d9d54cae31ad9b4584aa9504a9cfa1 (diff)
parent9803af291162dbca4b9773586a3f5c392f0dd974 (diff)
downloadlinux-e789d4499abdb488dd9cabce4f95c74dac6bcbe5.tar.xz
Merge branch 'topic/kdump-hotplug' into next
Merge our topic branch containing kdump hotplug changes, more detail from the original cover letter: Commit 247262756121 ("crash: add generic infrastructure for crash hotplug support") added a generic infrastructure that allows architectures to selectively update the kdump image component during CPU or memory add/remove events within the kernel itself. This patch series adds crash hotplug handler for PowerPC and enable support to update the kdump image on CPU/Memory add/remove events. Among the 6 patches in this series, the first two patches make changes to the generic crash hotplug handler to assist PowerPC in adding support for this feature. The last four patches add support for this feature. The following section outlines the problem addressed by this patch series, along with the current solution, its shortcomings, and the proposed resolution. Problem: ======== Due to CPU/Memory hotplug or online/offline events the elfcorehdr (which describes the CPUs and memory of the crashed kernel) and FDT (Flattened Device Tree) of kdump image becomes outdated. Consequently, attempting dump collection with an outdated elfcorehdr or FDT can lead to failed or inaccurate dump collection. Going forward CPU hotplug or online/offline events are referred as CPU/Memory add/remove events. Existing solution and its shortcoming: ====================================== The current solution to address the above issue involves monitoring the CPU/memory add/remove events in userspace using udev rules and whenever there are changes in CPU and memory resources, the entire kdump image is loaded again. The kdump image includes kernel, initrd, elfcorehdr, FDT, purgatory. Given that only elfcorehdr and FDT get outdated due to CPU/Memory add/remove events, reloading the entire kdump image is inefficient. More importantly, kdump remains inactive for a substantial amount of time until the kdump reload completes. Proposed solution: ================== Instead of initiating a full kdump image reload from userspace on CPU/Memory hotplug and online/offline events, the proposed solution aims to update only the necessary kdump image component within the kernel itself.
Diffstat (limited to 'include')
-rw-r--r--include/linux/crash_core.h15
-rw-r--r--include/linux/kexec.h11
-rw-r--r--include/uapi/linux/kexec.h1
3 files changed, 15 insertions, 12 deletions
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index d33352c2e386..44305336314e 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -37,17 +37,16 @@ static inline void arch_kexec_unprotect_crashkres(void) { }
#ifndef arch_crash_handle_hotplug_event
-static inline void arch_crash_handle_hotplug_event(struct kimage *image) { }
+static inline void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) { }
#endif
-int crash_check_update_elfcorehdr(void);
+int crash_check_hotplug_support(void);
-#ifndef crash_hotplug_cpu_support
-static inline int crash_hotplug_cpu_support(void) { return 0; }
-#endif
-
-#ifndef crash_hotplug_memory_support
-static inline int crash_hotplug_memory_support(void) { return 0; }
+#ifndef arch_crash_hotplug_support
+static inline int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
+{
+ return 0;
+}
#endif
#ifndef crash_get_elfcorehdr_size
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 060835bb82d5..5b93a5767413 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -319,8 +319,10 @@ struct kimage {
/* If set, we are using file mode kexec syscall */
unsigned int file_mode:1;
#ifdef CONFIG_CRASH_HOTPLUG
- /* If set, allow changes to elfcorehdr of kexec_load'd image */
- unsigned int update_elfcorehdr:1;
+ /* If set, it is safe to update kexec segments that are
+ * excluded from SHA calculation.
+ */
+ unsigned int hotplug_support:1;
#endif
#ifdef ARCH_HAS_KIMAGE_ARCH
@@ -391,9 +393,10 @@ bool kexec_load_permitted(int kexec_image_type);
/* List of defined/legal kexec flags */
#ifndef CONFIG_KEXEC_JUMP
-#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR)
+#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR | KEXEC_CRASH_HOTPLUG_SUPPORT)
#else
-#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR)
+#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR | \
+ KEXEC_CRASH_HOTPLUG_SUPPORT)
#endif
/* List of defined/legal kexec file flags */
diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h
index c17bb096ea68..5ae1741ea8ea 100644
--- a/include/uapi/linux/kexec.h
+++ b/include/uapi/linux/kexec.h
@@ -13,6 +13,7 @@
#define KEXEC_ON_CRASH 0x00000001
#define KEXEC_PRESERVE_CONTEXT 0x00000002
#define KEXEC_UPDATE_ELFCOREHDR 0x00000004
+#define KEXEC_CRASH_HOTPLUG_SUPPORT 0x00000008
#define KEXEC_ARCH_MASK 0xffff0000
/*