Re: [PATCH v3 2/4] kaslr: calculate the memory region in immovable node

[Baoquan He]

On 12/05/17 at 11:40am, Kees Cook wrote:
> On Tue, Dec 5, 2017 at 12:51 AM, Chao Fan <fanc.f...@cn.fujitsu.com> wrote:
> > If there is no immovable memory region specified, go on the old code.
> > There are several conditons:
> > 1. CONFIG_MEMORY_HOTPLUG is not specified to y.
> > 2. immovable_mem= is not specified.
> >
> > Otherwise, calculate the intersecting between memmap entry and
> > immovable memory.
> 
> Instead of copy/pasting code between process_efi_entries() and
> process_e820_entries(), I'd rather that process_mem_region() is
> modified to deal with immovable regions.

If put it into process_mem_region(), one level of loop is added. How
about changing it like below. If no immovable_mem, just process the
region in process_immovable_mem(). This we don't need to touch
process_mem_region().


>From 9ae3f5ab0e2f129757495af2412bd52dcf86aa46 Mon Sep 17 00:00:00 2001
From: Baoquan He <b...@redhat.com>
Date: Wed, 6 Dec 2017 17:24:55 +0800
Subject: [PATCH] KASLR: change code

Signed-off-by: Baoquan He <b...@redhat.com>
---
 arch/x86/boot/compressed/kaslr.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 13d26b859c69..73b1562a7439 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -638,13 +638,23 @@ static bool process_immovable_mem(struct mem_vector 
region,
                                  unsigned long long minimum,
                                  unsigned long long image_size)
 {
-       int i;
+       /* If no immovable_mem stored, use region directly */
+       if (num_immovable_region == 0) {
+               process_mem_region(&entry, minimum, image_size);
+
+               if (slot_area_index == MAX_SLOT_AREA) {
+                       debug_putstr("Aborted memmap scan (slot_areas 
full)!\n");
+                       return 1;
+               }
+
+               return 0;
+       }
 
        /*
         * Walk all immovable regions, and filter the intersection
         * to process_mem_region.
         */
-       for (i = 0; i < num_immovable_region; i++) {
+       for (int i = 0; i < num_immovable_region; i++) {
                struct mem_vector entry;
                unsigned long long start, end, entry_end;
 
@@ -738,14 +748,7 @@ process_efi_entries(unsigned long minimum, unsigned long 
image_size)
                region.start = md->phys_addr;
                region.size = md->num_pages << EFI_PAGE_SHIFT;
 
-               /* If no immovable_mem stored, use region directly */
-               if (num_immovable_region == 0) {
-                       process_mem_region(&region, minimum, image_size);
-                       if (slot_area_index == MAX_SLOT_AREA) {
-                               debug_putstr("Aborted memmap scan (slot_areas 
full)!\n");
-                               break;
-                       }
-               } else if (process_immovable_mem(region, minimum, image_size))
+               if (process_immovable_mem(region, minimum, image_size))
                        break;
        }
        return true;
@@ -774,14 +777,7 @@ static void process_e820_entries(unsigned long minimum,
                region.start = entry->addr;
                region.size = entry->size;
 
-               /* If no immovable_mem stored, use region directly */
-               if (num_immovable_region == 0) {
-                       process_mem_region(&region, minimum, image_size);
-                       if (slot_area_index == MAX_SLOT_AREA) {
-                               debug_putstr("Aborted memmap scan (slot_areas 
full)!\n");
-                               break;
-                       }
-               } else if (process_immovable_mem(region, minimum, image_size))
+               if (process_immovable_mem(region, minimum, image_size))
                        break;
        }
 }
-- 
2.5.5