[PATCH v9 2/5] x86/KASLR: Handle the memory regions specified in kaslr_boot_mem

Chao Fan
2018-02-28T10:52:35Z

If no 'kaslr_boot_mem=' specified, just handle the e820/efi entries
directly as before. Otherwise, limit kernel to memory regions
specified in 'kaslr_boot_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.fnst@cn.fujitsu.com>
Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Baoquan He <bhe@redhat.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 e33e5cbf7244..eb47502fbe54 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -554,9 +554,9 @@ 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;
@@ -633,6 +633,52 @@ 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_boot_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_boot_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
@@ -698,11 +744,9 @@ 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;
}
@@ -729,11 +773,9 @@ 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