s390/kexec: consolidate crash_map/unmap_reserved_pages() and arch_kexec_protect(unprotect)_crashkres()

Commit 3f625002581b ("kexec: introduce a protection mechanism for the
crashkernel reserved memory") is a similar mechanism for protecting the
crash kernel reserved memory to previous crash_map/unmap_reserved_pages()
implementation, the new one is more generic in name and cleaner in code
(besides, some arch may not be allowed to unmap the pgtable).

Therefore, this patch consolidates them, and uses the new
arch_kexec_protect(unprotect)_crashkres() to replace former
crash_map/unmap_reserved_pages() which by now has been only used by
S390.

The consolidation work needs the crash memory to be mapped initially,
this is done in machine_kdump_pm_init() which is after
reserve_crashkernel().  Once kdump kernel is loaded, the new
arch_kexec_protect_crashkres() implemented for S390 will actually
unmap the pgtable like before.

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Minfei Huang <mhuang@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 2 insertions, 21 deletions

diff --git a/kernel/kexec.c b/kernel/kexec.c
index b73dc211fcfd..4384672d3245 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -136,9 +136,6 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
         if (ret)
                 return ret;
 
-        if (flags & KEXEC_ON_CRASH)
-                crash_map_reserved_pages();
-
         if (flags & KEXEC_PRESERVE_CONTEXT)
                 image->preserve_context = 1;
 
@@ -161,12 +158,6 @@ out:
         if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
                 arch_kexec_protect_crashkres();
 
-        /*
-         * Once the reserved memory is mapped, we should unmap this memory
-         * before returning
-         */
-        if (flags & KEXEC_ON_CRASH)
-                crash_unmap_reserved_pages();
         kimage_free(image);
         return ret;
 }
@@ -232,9 +223,6 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
 
         result = do_kexec_load(entry, nr_segments, segments, flags);
 
-        if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
-                arch_kexec_protect_crashkres();
-
         mutex_unlock(&kexec_mutex);
 
         return result;
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 48b73cc8e425..56b3ed0927b0 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -954,7 +954,6 @@ int crash_shrink_memory(unsigned long new_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))
@@ -968,7 +967,6 @@ int crash_shrink_memory(unsigned long new_size)
         crashk_res.end = end - 1;
 
         insert_resource(&iomem_resource, ram_res);
-        crash_unmap_reserved_pages();
 
 unlock:
         mutex_unlock(&kexec_mutex);
@@ -1553,17 +1551,12 @@ int kernel_kexec(void)
 }
 
 /*
- * Add and remove page tables for crashkernel memory
+ * Protection mechanism for crashkernel reserved memory after
+ * the kdump kernel is loaded.
  *
  * 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)
-{}
-
 void __weak arch_kexec_protect_crashkres(void)
 {}