On Fri, 10 Jul 2015 13:12:17 +0800
Minfei Huang <mnfhuang at gmail.com> wrote:
> For some arch, kexec shall map the reserved pages, then use them, when
> we try to start the kdump service.
>
> Now kexec will never unmap the reserved pages, once it fails to continue
> starting the kdump service. So we make a pair of map/unmap reserved
> pages whatever kexec fails or not in code path.
>
> In order to make code readable, wrap a new function __kexec_load which
> contains all of the logic to deal with the image loading.
>
> Signed-off-by: Minfei Huang <mnfhuang at gmail.com>
> ---
> v3:
> - reconstruct the patch, wrap a new function to deal with the code logic, based on Vivek and Michael's patch
> v2:
> - replace the "failure" label with "fail_unmap_pages"
> v1:
> - reconstruct the patch code
> ---
> kernel/kexec.c | 112 ++++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 63 insertions(+), 49 deletions(-)
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index a785c10..2232c90 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -1247,10 +1247,71 @@ int kexec_load_disabled;
>
> static DEFINE_MUTEX(kexec_mutex);
>
> +static int __kexec_load(unsigned long entry, unsigned long nr_segments,
> + struct kexec_segment __user *segments,
> + unsigned long flags)
> +{
> + int result = 0;
> + struct kimage **dest_image, *image;
> +
> + dest_image = &kexec_image;
> +
> + if (flags & KEXEC_ON_CRASH)
> + dest_image = &kexec_crash_image;
> +
> + if (nr_segments == 0) {
> + /* Install the new kernel, and Uninstall the old */
> + image = xchg(dest_image, image);
> + kimage_free(image);
Well this is wrong and should probably be:
if (nr_segments == 0) {
/* Uninstall image */
image = xchg(dest_image, NULL);
kimage_free(image);
> + } else {
> + unsigned long i;
> +
> + if (flags & KEXEC_ON_CRASH) {
> + /*
[snip]
> + result = kimage_load_segment(image, &image->segment[i]);
> + if (result)
> + goto failure_unmap_mem;
> + }
> +
> + kimage_terminate(image);
> +
> + /* Install the new kernel, and Uninstall the old */
Perhaps fix the comment: Remove superfluous blank and lowercase "uninstall"?
> + image = xchg(dest_image, image);
> +
> +failure_unmap_mem:
> + if (flags & KEXEC_ON_CRASH)
> + crash_unmap_reserved_pages();
> + kimage_free(image);
Here the update patch:
---
diff --git a/kernel/kexec.c b/kernel/kexec.c
index e686a39..2f5b4aa 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1249,8 +1249,8 @@ static int __kexec_load(unsigned long entry, unsigned long nr_segments,
dest_image = &kexec_crash_image;
if (nr_segments == 0) {
- /* Install the new kernel, and Uninstall the old */
- image = xchg(dest_image, image);
+ /* Uninstall image */
+ image = xchg(dest_image, NULL);
kimage_free(image);
} else {
unsigned long i;
@@ -1287,7 +1287,7 @@ static int __kexec_load(unsigned long entry, unsigned long nr_segments,
kimage_terminate(image);
- /* Install the new kernel, and Uninstall the old */
+ /* Install the new kernel, and uninstall the old */
image = xchg(dest_image, image);
failure_unmap_mem:
