[PATCH v6 11/14] crash: Factor out crash_find_elfcorehdr() helper

[Jinjie Ruan]

The elfcorehdr segment is located by scanning the segments for
the ELF magic. Factor that scan out into a new helper function,
crash_find_elfcorehdr(), to clean up crash_handle_hotplug_event()
and prepare for its reuse in crash hotplug code.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Baoquan He <baoquan.he@xxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Pratyush Yadav <pratyush@xxxxxxxxxx>
Cc: Dave Young <ruirui.yang@xxxxxxxxx>
Cc: Breno Leitao <leitao@xxxxxxxxxx>
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 kernel/crash_core.c | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 406b68d2adfd..4a990b17b66c 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -647,6 +647,28 @@ int crash_check_hotplug_support(void)
 	return rc;
 }
 
+static void crash_find_elfcorehdr(struct kimage *image)
+{
+	unsigned char *ptr;
+	unsigned long mem;
+	unsigned int n;
+
+	if (image->elfcorehdr_index >= 0)
+		return;
+
+	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)
+			continue;
+
+		/* The segment containing elfcorehdr */
+		if (memcmp(ptr, ELFMAG, SELFMAG) == 0)
+			image->elfcorehdr_index = (int)n;
+		kunmap_local(ptr);
+	}
+}
+
 /*
  * To accurately reflect hot un/plug changes of CPU and Memory resources
  * (including onling and offlining of those resources), the relevant
@@ -702,22 +724,7 @@ static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu,
 	 * is allocated. Find the segment containing the elfcorehdr,
 	 * if not already found.
 	 */
-	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);
-			}
-		}
-	}
+	crash_find_elfcorehdr(image);
 
 	if (image->elfcorehdr_index < 0) {
 		pr_err("unable to locate elfcorehdr segment");
-- 
2.34.1