kdump: Allow shrinking of kdump region to be overridden

On ppc64 the crashkernel region almost always overlaps an area of firmware.
This works fine except when using the sysfs interface to reduce the kdump
region. If we free the firmware area we are guaranteed to crash.

Rename free_reserved_phys_range to crash_free_reserved_phys_range and make
it a weak function so we can override it.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/kexec.c b/kernel/kexec.c
index ec19b92c7ebd..4e240a378df6 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1099,7 +1099,8 @@ size_t crash_get_memory_size(void)
         return size;
 }
 
-static void free_reserved_phys_range(unsigned long begin, unsigned long end)
+void __weak crash_free_reserved_phys_range(unsigned long begin,
+                                           unsigned long end)
 {
         unsigned long addr;
 
@@ -1135,7 +1136,7 @@ int crash_shrink_memory(unsigned long new_size)
         start = roundup(start, PAGE_SIZE);
         end = roundup(start + new_size, PAGE_SIZE);
 
-        free_reserved_phys_range(end, crashk_res.end);
+        crash_free_reserved_phys_range(end, crashk_res.end);
 
         if ((start == end) && (crashk_res.parent != NULL))
                 release_resource(&crashk_res);