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Subject[RFC PATCH 4/4] x86/boot/KASLR: Limit kaslr to choosing the immovable memory
Date
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.

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>
---
arch/x86/boot/compressed/kaslr.c | 65 ++++++++++++++++++++++++++------
1 file changed, 54 insertions(+), 11 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 4edff0501540..a0a07e549ef8 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -545,9 +545,9 @@ 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;
@@ -624,6 +624,55 @@ 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 hotplug memory found, filter the intersection between
+ * immovable memory and region to slots_count.
+ */
+ 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 hotplug memory found, 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
@@ -689,11 +738,8 @@ 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;
}
@@ -720,11 +766,8 @@ 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;
- }
}
}

--
2.17.0


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