2 files changed, 25 insertions, 2 deletions

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 07d9aba75562..fe45136b32cc 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -37,6 +37,10 @@
 #define KEXEC_CRASH_CONTROL_MEMORY_LIMIT KEXEC_CONTROL_MEMORY_LIMIT
 #endif
 
+#ifndef KEXEC_CRASH_MEM_ALIGN
+#define KEXEC_CRASH_MEM_ALIGN PAGE_SIZE
+#endif
+
 #define KEXEC_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
 #define KEXEC_CORE_NOTE_NAME "CORE"
 #define KEXEC_CORE_NOTE_NAME_BYTES ALIGN(sizeof(KEXEC_CORE_NOTE_NAME), 4)
@@ -133,6 +137,8 @@ extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);
 void crash_save_cpu(struct pt_regs *regs, int cpu);
 void crash_save_vmcoreinfo(void);
+void crash_map_reserved_pages(void);
+void crash_unmap_reserved_pages(void);
 void arch_crash_save_vmcoreinfo(void);
 void vmcoreinfo_append_str(const char *fmt, ...)
         __attribute__ ((format (printf, 1, 2)));
diff --git a/kernel/kexec.c b/kernel/kexec.c
index d3b8a4ceb90b..dc7bc0829286 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -999,6 +999,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
                         kimage_free(xchg(&kexec_crash_image, NULL));
                         result = kimage_crash_alloc(&image, entry,
                                                      nr_segments, segments);
+                        crash_map_reserved_pages();
                 }
                 if (result)
                         goto out;
@@ -1015,6 +1016,8 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
                                 goto out;
                 }
                 kimage_terminate(image);
+                if (flags & KEXEC_ON_CRASH)
+                        crash_unmap_reserved_pages();
         }
         /* Install the new kernel, and  Uninstall the old */
         image = xchg(dest_image, image);
@@ -1026,6 +1029,18 @@ out:
         return result;
 }
 
+/*
+ * Add and remove page tables for crashkernel memory
+ *
+ * Provide an empty default implementation here -- architecture
+ * code may override this
+ */
+void __weak crash_map_reserved_pages(void)
+{}
+
+void __weak crash_unmap_reserved_pages(void)
+{}
+
 #ifdef CONFIG_COMPAT
 asmlinkage long compat_sys_kexec_load(unsigned long entry,
                                 unsigned long nr_segments,
@@ -1134,14 +1149,16 @@ int crash_shrink_memory(unsigned long new_size)
                 goto unlock;
         }
 
-        start = roundup(start, PAGE_SIZE);
-        end = roundup(start + new_size, PAGE_SIZE);
+        start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
+        end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);
 
+        crash_map_reserved_pages();
         crash_free_reserved_phys_range(end, crashk_res.end);
 
         if ((start == end) && (crashk_res.parent != NULL))
                 release_resource(&crashk_res);
         crashk_res.end = end - 1;
+        crash_unmap_reserved_pages();
 
 unlock:
         mutex_unlock(&kexec_mutex);