[PATCH v7 2/5] x86/KASLR: Handle the memory regions specified in kaslr_mem

[Chao Fan]

If no 'kaslr_mem=' specified, just handle the e820/efi entries directly
as before. Otherwise, limit kernel to memory regions specified in
'kaslr_mem=' commandline.

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 | 64 +++++++++++++++++++++++++++++++++-------
 1 file changed, 53 insertions(+), 11 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index b21741135673..b200a7ceafc1 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -548,9 +548,9 @@ 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;
@@ -627,6 +627,52 @@ 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)
+{
+       /*
+        * If kaslr_mem= specified, walk all the regions, and
+        * filter the intersection to slots_count.
+        */
+       if (num_usable_region > 0) {
+               int i;
+
+               for (i = 0; i < num_usable_region; i++) {
+                       struct mem_vector entry;
+                       unsigned long long start, end, entry_end, region_end;
+
+                       start = mem_usable[i].start;
+                       end = start + mem_usable[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 < 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;
+       }
+
+       /*
+        * If no kaslr_mem stored, use region directly
+        */
+       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
@@ -692,11 +738,9 @@ 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;
 }
@@ -723,11 +767,9 @@ 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;
-               }
        }
 }
 
-- 
2.14.3