[PATCH v4 4/4] x86/boot/KASLR: Limit kaslr to choosing the immovable memory

[Chao Fan]

If 'CONFIG_MEMORY_HOTREMOVE' specified and the account of immovable
memory regions is not zero. Calculate the intersection between memory
regions from e820/efi memory table and immovable memory regions.
Or go on the old code.

Rename process_mem_region to slots_count to match slots_fetch_random,
and name new function as process_mem_region.

Signed-off-by: Chao Fan <fanc.f...@cn.fujitsu.com>
---
 arch/x86/boot/compressed/kaslr.c | 66 ++++++++++++++++++++++++++------
 1 file changed, 55 insertions(+), 11 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 4705682caf1f..10bda3a1fcaa 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -631,9 +631,9 @@ static unsigned long slots_fetch_random(void)
        return 0;
 }
 
-static void process_mem_region(struct mem_vector *entry,
-                              unsigned long minimum,
-                              unsigned long image_size)
+static void slots_count(struct mem_vector *entry,
+                       unsigned long minimum,
+                       unsigned long image_size)
 {
        struct mem_vector region, overlap;
        struct slot_area slot_area;
@@ -710,6 +710,56 @@ static void process_mem_region(struct mem_vector *entry,
        }
 }
 
+static bool process_mem_region(struct mem_vector *region,
+                              unsigned long long minimum,
+                              unsigned long long image_size)
+{
+#ifdef CONFIG_MEMORY_HOTREMOVE
+       /*
+        * If immovable memory found, filter the intersection between
+        * immovable memory and region to slots_count.
+        * Otherwise, go on old code.
+        */
+       if (num_immovable_mem > 0) {
+               int i;
+
+               for (i = 0; i < num_immovable_mem; i++) {
+                       struct mem_vector entry;
+                       unsigned long long start, end, entry_end, region_end;
+
+                       start = immovable_mem[i].start;
+                       end = start + immovable_mem[i].size;
+                       region_end = region->start + region->size;
+
+                       entry.start = clamp(region->start, start, end);
+                       entry_end = clamp(region_end, start, end);
+
+                       if (entry.start + image_size < entry_end) {
+                               entry.size = entry_end - entry.start;
+                               slots_count(&entry, minimum, image_size);
+
+                               if (slot_area_index == MAX_SLOT_AREA) {
+                                       debug_putstr("Aborted e820/efi memmap 
scan (slot_areas full)!\n");
+                                       return 1;
+                               }
+                       }
+               }
+               return 0;
+       }
+#endif
+       /*
+        * If no immovable memory found, or MEMORY_HOTREMOVE disabled,
+        * walk all the regions, so use region directely.
+        */
+       slots_count(region, minimum, image_size);
+
+       if (slot_area_index == MAX_SLOT_AREA) {
+               debug_putstr("Aborted e820/efi memmap scan (slot_areas 
full)!\n");
+               return 1;
+       }
+       return 0;
+}
+
 #ifdef CONFIG_EFI
 /*
  * Returns true if mirror region found (and must have been processed
@@ -775,11 +825,8 @@ process_efi_entries(unsigned long minimum, unsigned long 
image_size)
 
                region.start = md->phys_addr;
                region.size = md->num_pages << EFI_PAGE_SHIFT;
-               process_mem_region(&region, minimum, image_size);
-               if (slot_area_index == MAX_SLOT_AREA) {
-                       debug_putstr("Aborted EFI scan (slot_areas full)!\n");
+               if (process_mem_region(&region, minimum, image_size))
                        break;
-               }
        }
        return true;
 }
@@ -806,11 +853,8 @@ static void process_e820_entries(unsigned long minimum,
                        continue;
                region.start = entry->addr;
                region.size = entry->size;
-               process_mem_region(&region, minimum, image_size);
-               if (slot_area_index == MAX_SLOT_AREA) {
-                       debug_putstr("Aborted e820 scan (slot_areas full)!\n");
+               if (process_mem_region(&region, minimum, image_size))
                        break;
-               }
        }
 }
 
-- 
2.17.1