[PATCH v2 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>
Cc: kexec@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 include/linux/kexec.h |  4 +++
 kernel/kexec_file.c   | 88 +++++++++++++++++++++++++++++++++++----------------
 2 files changed, 64 insertions(+), 28 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 7321043aa65a..a08cd986b5a1 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -210,6 +210,10 @@ extern asmlinkage long sys_kexec_load(unsigned long entry,
 					struct kexec_segment __user *segments,
 					unsigned long flags);
 extern int kernel_kexec(void);
+int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
+			  unsigned long align, unsigned long min_addr,
+			  unsigned long max_addr, bool top_down,
+			  unsigned long *addr);
 extern int kexec_add_buffer(struct kimage *image, char *buffer,
 			    unsigned long bufsz, unsigned long memsz,
 			    unsigned long buf_align, unsigned long buf_min,
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index a3ca7cfe070e..3e494261d32a 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -453,6 +453,57 @@ int __weak arch_kexec_walk_mem(unsigned int image_type, unsigned long start,
 		return walk_system_ram_res(start, end, data, func);
 }
 
+/**
+ * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
+ * @image:	kexec image being updated.
+ * @size:	Memory size.
+ * @align:	Minimum alignment needed.
+ * @min_addr:	Minimum starting address.
+ * @max_addr:	Maximum end address.
+ * @top_down	Find the highest free memory region?
+ * @addr	On success, will have start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
+			  unsigned long align, unsigned long min_addr,
+			  unsigned long max_addr, bool top_down,
+			  unsigned long *addr)
+{
+	int ret;
+	struct kexec_buf buf;
+	unsigned long start, end;
+
+	memset(&buf, 0, sizeof(struct kexec_buf));
+	buf.image = image;
+
+	buf.memsz = size;
+	buf.buf_align = align;
+	buf.buf_min = min_addr;
+	buf.buf_max = max_addr;
+	buf.top_down = top_down;
+
+	/* Walk the RAM ranges and allocate a suitable range for the buffer */
+	if (image->type == KEXEC_TYPE_CRASH) {
+		start = crashk_res.start;
+		end = crashk_res.end;
+	} else {
+		start = 0;
+		end = ULONG_MAX;
+	}
+
+	ret = arch_kexec_walk_mem(image->type, start, end, top_down, &buf,
+				  locate_mem_hole_callback);
+	if (ret != 1) {
+		/* A suitable memory range could not be found for buffer */
+		return -EADDRNOTAVAIL;
+	}
+
+	*addr = buf.mem;
+
+	return 0;
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -464,9 +515,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 {
 
 	struct kexec_segment *ksegment;
-	struct kexec_buf buf, *kbuf;
 	int ret;
-	unsigned long start, end;
+	unsigned long addr, align, size;
 
 	/* Currently adding segment this way is allowed only in file mode */
 	if (!image->file_mode)
@@ -487,38 +537,20 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 		return -EINVAL;
 	}
 
-	memset(&buf, 0, sizeof(struct kexec_buf));
-	kbuf = &buf;
-	kbuf->image = image;
-
-	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
-	kbuf->buf_align = max(buf_align, PAGE_SIZE);
-	kbuf->buf_min = buf_min;
-	kbuf->buf_max = buf_max;
-	kbuf->top_down = top_down;
+	size = ALIGN(memsz, PAGE_SIZE);
+	align = max(buf_align, PAGE_SIZE);
 
-	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	if (image->type == KEXEC_TYPE_CRASH) {
-		start = crashk_res.start;
-		end = crashk_res.end;
-	} else {
-		start = 0;
-		end = ULONG_MAX;
-	}
-
-	ret = arch_kexec_walk_mem(image->type, start, end, top_down, 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(image, size, align, buf_min, buf_max,
+				    top_down, &addr);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
 	ksegment->kbuf = buffer;
 	ksegment->bufsz = bufsz;
-	ksegment->mem = kbuf->mem;
-	ksegment->memsz = kbuf->memsz;
+	ksegment->mem = addr;
+	ksegment->memsz = size;
 	image->nr_segments++;
 	*load_addr = ksegment->mem;
 	return 0;
-- 
1.9.1