[v1 4/5] kexec: use reserved memory for normal kexec reboot

[Pavel Tatashin]

If memory was reserved for the given segment use it directly instead of
allocating on per-page bases. This will avoid relocating this segment to
final destination when machine is rebooted.

This is done on a per segment bases because user might decide to always
load kernel segments at the given address (i.e. non-relocatable kernel),
but load initramfs at reserved address, and thus save reboot time on
copying initramfs if it is large, and reduces reboot performance.

Signed-off-by: Pavel Tatashin <pasha.tatas...@soleen.com>
---
 kernel/kexec_core.c | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 932feadbeb3a..2a8d8746e0a1 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -154,6 +154,18 @@ static struct page *kimage_alloc_page(struct kimage *image,
                                       gfp_t gfp_mask,
                                       unsigned long dest);
 
+/* Check whether this segment is fully within the resource */
+static bool segment_is_reserved(struct kexec_segment *seg, struct resource 
*res)
+{
+       unsigned long mstart = seg->mem;
+       unsigned long mend = mstart + seg->memsz - 1;
+
+       if (mstart < phys_to_boot_phys(res->start) ||
+           mend > phys_to_boot_phys(res->end))
+               return false;
+       return true;
+}
+
 int sanity_check_segment_list(struct kimage *image)
 {
        int i;
@@ -246,13 +258,9 @@ int sanity_check_segment_list(struct kimage *image)
 
        if (image->type == KEXEC_TYPE_CRASH) {
                for (i = 0; i < nr_segments; i++) {
-                       unsigned long mstart, mend;
-
-                       mstart = image->segment[i].mem;
-                       mend = mstart + image->segment[i].memsz - 1;
                        /* Ensure we are within the crash kernel limits */
-                       if ((mstart < phys_to_boot_phys(crashk_res.start)) ||
-                           (mend > phys_to_boot_phys(crashk_res.end)))
+                       if (!segment_is_reserved(&image->segment[i],
+                                                &crashk_res))
                                return -EADDRNOTAVAIL;
                }
        }
@@ -848,12 +856,13 @@ static int kimage_load_normal_segment(struct kimage 
*image,
        return result;
 }
 
-static int kimage_load_crash_segment(struct kimage *image,
-                                       struct kexec_segment *segment)
+static int kimage_load_crash_or_reserved_segment(struct kimage *image,
+                                                struct kexec_segment *segment)
 {
-       /* For crash dumps kernels we simply copy the data from
-        * user space to it's destination.
-        * We do things a page at a time for the sake of kmap.
+       /*
+        * For crash dumps and kexec-reserved kernels we simply copy the data
+        * from user space to it's destination. We do things a page at a time
+        * for the sake of kmap.
         */
        unsigned long maddr;
        size_t ubytes, mbytes;
@@ -923,10 +932,14 @@ int kimage_load_segment(struct kimage *image,
 
        switch (image->type) {
        case KEXEC_TYPE_DEFAULT:
-               result = kimage_load_normal_segment(image, segment);
+               if (segment_is_reserved(segment, &kexeck_res))
+                       result = kimage_load_crash_or_reserved_segment(image,
+                                                                      segment);
+               else
+                       result = kimage_load_normal_segment(image, segment);
                break;
        case KEXEC_TYPE_CRASH:
-               result = kimage_load_crash_segment(image, segment);
+               result = kimage_load_crash_or_reserved_segment(image, segment);
                break;
        }
 
-- 
2.22.0