[PATCH v8 3/8] powerpc/crash: update kimage_arch struct

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Add a new member "fdt_index" to kimage_arch struct to hold the index of
the FDT (Flattened Device Tree) segment in the kexec segment array.

Having direct access to FDT segment will help arch crash hotplug handler
to avoid looping kexec segment array to identify the FDT segment index
for every FDT update on hotplug events.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 arch/powerpc/include/asm/kexec.h |  7 +++++++
 arch/powerpc/kexec/core_64.c     | 33 ++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 8090ad7d97d9d..5a322c1737661 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -103,6 +103,10 @@ 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);
+#if defined(CONFIG_CRASH_HOTPLUG)
+int machine_kexec_post_load(struct kimage *image);
+#define machine_kexec_post_load machine_kexec_post_load
+#endif
 #endif
 
 #if defined(CONFIG_CRASH_DUMP) && defined(CONFIG_PPC_RTAS)
@@ -118,6 +122,9 @@ 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..a9918084b1eba 100644
--- a/arch/powerpc/kexec/core_64.c
+++ b/arch/powerpc/kexec/core_64.c
@@ -77,6 +77,39 @@ int machine_kexec_prepare(struct kimage *image)
 	return 0;
 }
 
+#if defined(CONFIG_CRASH_HOTPLUG)
+/*
+ * Find the index of the FDT segment in kexec segment array and assign
+ * it to kimage's member fdt_index to have direct access to FDT
+ * segment later on.
+ */
+int machine_kexec_post_load(struct kimage *kimage)
+{
+	int i;
+	void *ptr;
+	unsigned long mem;
+
+	/* Mark fdt_index invalid */
+	kimage->arch.fdt_index = -1;
+
+	/* fdt_index remains invalid for if it not crash kernel load */
+	if (kimage->type != KEXEC_TYPE_CRASH)
+		return 0;
+
+	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;
+		}
+	}
+
+	return 0;
+}
+#endif
+
 /* Called during kexec sequence with MMU off */
 static notrace void copy_segments(unsigned long ind)
 {
-- 
2.39.1