[PATCH v4 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
implementation to find free memory for the purgatory stack.

Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
---
 include/linux/kexec.h |  1 +
 kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ff5fa7707bd7..803f563df81d 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -174,6 +174,7 @@ struct kexec_buf {
 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 			       int (*func)(u64, u64, void *));
 extern int kexec_add_buffer(struct kexec_buf *kbuf);
+int kexec_locate_mem_hole(struct kexec_buf *kbuf);
 #endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 82ccfc4ee97e..3125d1689712 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -450,6 +450,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 }
 
 /**
+ * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
+ * @kbuf:	Parameters for the memory search.
+ *
+ * On success, kbuf->mem will have the start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kexec_buf *kbuf)
+{
+	int ret;
+
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
+
+	return ret == 1 ? 0 : -EADDRNOTAVAIL;
+}
+
+/**
  * kexec_add_buffer - place a buffer in a kexec segment
  * @kbuf:	Buffer contents and memory parameters.
  *
@@ -489,11 +506,9 @@ int kexec_add_buffer(struct kexec_buf *kbuf)
 	kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
-	if (ret != 1) {
-		/* A suitable memory range could not be found for buffer */
-		return -EADDRNOTAVAIL;
-	}
+	ret = kexec_locate_mem_hole(kbuf);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
-- 
1.9.1