[Patch] kexec: increase max of kexec segments and use dynamic allocation

Amerigo Wang
2010-07-22T06:14:10Z

Currently KEXEC_SEGMENT_MAX is only 16 which is too small for machine with
many memory ranges. Increase this hard limit to 1024 which is reasonably large,
and change ->segment from a static array to a dynamically allocated memory.

Cc: nhorman@redhat.com
Cc: ebiederm@xmission.com
Signed-off-by: WANG Cong <amwang@redhat.com>

---
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index ed31a29..f115585 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -131,10 +131,7 @@ static void copy_segments(unsigned long ind)
void kexec_copy_flush(struct kimage *image)
{
long i, nr_segments = image->nr_segments;
- struct kexec_segment ranges[KEXEC_SEGMENT_MAX];
-
- /* save the ranges on the stack to efficiently flush the icache */
- memcpy(ranges, image->segment, sizeof(ranges));
+ struct kexec_segment range;

/*
* After this call we may not use anything allocated in dynamic
@@ -148,9 +145,11 @@ void kexec_copy_flush(struct kimage *image)
* we need to clear the icache for all dest pages sometime,
* including ones that were in place on the original copy
*/
- for (i = 0; i < nr_segments; i++)
- flush_icache_range((unsigned long)__va(ranges[i].mem),
- (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
+ for (i = 0; i < nr_segments; i++) {
+ memcpy(&range, &image->segment[i], sizeof(range));
+ flush_icache_range((unsigned long)__va(range.mem),
+ (unsigned long)__va(range.mem + range.memsz));
+ }
}

#ifdef CONFIG_SMP
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 03e8e8d..26b70ff 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -57,7 +57,7 @@ typedef unsigned long kimage_entry_t;
#define IND_DONE 0x4
#define IND_SOURCE 0x8

-#define KEXEC_SEGMENT_MAX 16
+#define KEXEC_SEGMENT_MAX 1024
struct kexec_segment {
void __user *buf;
size_t bufsz;
@@ -86,7 +86,7 @@ struct kimage {
struct page *swap_page;

unsigned long nr_segments;
- struct kexec_segment segment[KEXEC_SEGMENT_MAX];
+ struct kexec_segment *segment;

struct list_head control_pages;
struct list_head dest_pages;
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 131b170..3f97309 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -131,6 +131,11 @@ static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
if (!image)
goto out;

+ image->segment = kzalloc(nr_segments * sizeof(struct kexec_segment),
+ GFP_KERNEL);
+ if (!image->segment)
+ goto out;
+
image->head = 0;
image->entry = &image->head;
image->last_entry = &image->head;
@@ -216,8 +221,10 @@ static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
out:
if (result == 0)
*rimage = image;
- else
+ else if (image) {
+ kfree(image->segment);
kfree(image);
+ }

return result;

@@ -261,8 +268,10 @@ static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry,
out:
if (result == 0)
*rimage = image;
- else
+ else if (image) {
+ kfree(image->segment);
kfree(image);
+ }

return result;
}
@@ -330,8 +339,10 @@ static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
out:
if (result == 0)
*rimage = image;
- else
+ else if (image) {
+ kfree(image->segment);
kfree(image);
+ }

return result;
}
@@ -656,6 +667,7 @@ static void kimage_free(struct kimage *image)

/* Free the kexec control pages... */
kimage_free_page_list(&image->control_pages);
+ kfree(image->segment);
kfree(image);
}