[PATCH v9 3/6] powerpc/crash: add a new member to the kimage_arch struct

[Sourabh Jain]

A new member "fdt_index" is added to the kimage_arch struct to hold
the index of the FDT (Flattened Device Tree) segment from the kexec
the segment array.

fdt_index will provide direct access to the FDT segment in the kexec
segment array after the kdump kernel is loaded.

The new attribute will be used in the arch crash hotplug handler
(added in upcoming patches) on every CPU and memory hotplug event.

The fdt_index is populated for both kexec_load and kexec_file_load
case.

Signed-off-by: Sourabh Jain <sourabhjain at linux.ibm.com>
---
 arch/powerpc/include/asm/kexec.h |  5 +++++
 arch/powerpc/kexec/core_64.c     | 31 +++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 8090ad7d97d9d..348eb96e8ca67 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -103,6 +103,8 @@ void kexec_copy_flush(struct kimage *image);
 struct crash_mem;
 int update_cpus_node(void *fdt);
 int get_crash_memory_ranges(struct crash_mem **mem_ranges);
+int machine_kexec_post_load(struct kimage *image);
+#define machine_kexec_post_load machine_kexec_post_load
 #endif
 
 #if defined(CONFIG_CRASH_DUMP) && defined(CONFIG_PPC_RTAS)
@@ -118,6 +120,9 @@ extern const struct kexec_file_ops kexec_elf64_ops;
 struct kimage_arch {
 	struct crash_mem *exclude_ranges;
 
+#if defined(CONFIG_CRASH_HOTPLUG)
+	int fdt_index;
+#endif
 	unsigned long backup_start;
 	void *backup_buf;
 	void *fdt;
diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c
index 0b292f93a74cc..531486c973988 100644
--- a/arch/powerpc/kexec/core_64.c
+++ b/arch/powerpc/kexec/core_64.c
@@ -77,6 +77,37 @@ int machine_kexec_prepare(struct kimage *image)
 	return 0;
 }
 
+int machine_kexec_post_load(struct kimage *kimage)
+{
+#if defined(CONFIG_CRASH_HOTPLUG)
+	int i;
+	void *ptr;
+	unsigned long mem;
+
+	/* Mark fdt_index invalid */
+	kimage->arch.fdt_index = -1;
+
+	/* fdt_index remains invalid if it is not a crash kernel load */
+	if (kimage->type != KEXEC_TYPE_CRASH)
+		return 0;
+	/*
+	 * Find the FDT segment index in kexec segment array and
+	 * assign it to kimage's member fdt_index to enable direct
+	 * access to FDT segment later on.
+	 */
+	for (i = 0; i < kimage->nr_segments; i++) {
+		mem = kimage->segment[i].mem;
+		ptr = __va(mem);
+
+		if (ptr && fdt_magic(ptr) == FDT_MAGIC) {
+			kimage->arch.fdt_index = i;
+			break;
+		}
+	}
+#endif
+	return 0;
+}
+
 /* Called during kexec sequence with MMU off */
 static notrace void copy_segments(unsigned long ind)
 {
-- 
2.39.1