The following is schematic diagram of the program before and after the
modification.
Before:
if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
if (memory_limit != PHYS_ADDR_MAX) {} --(b)
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
After:
if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
if (memory_limit != PHYS_ADDR_MAX) {} --(b)
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
After grouping modification of memstart_address by moving linear region
randomization ahead of memory_init, driver can safely using macro,
__phys_to_virt, in (b) or (c), if necessary.
Signed-off-by: pierre Kuo <vichy....@gmail.com>
---
Changes in v2:
- add Fixes tag
Changes in v3:
- adding patch of shifting linear region randomization ahead of
memory_limit
arch/arm64/mm/init.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 7205a9085b4d..5142020fc146 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -389,6 +389,23 @@ void __init arm64_memblock_init(void)
memblock_remove(0, memstart_addr);
}
+ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+ extern u16 memstart_offset_seed;
+ u64 range = linear_region_size -
+ (memblock_end_of_DRAM() - memblock_start_of_DRAM());
+
+ /*
+ * If the size of the linear region exceeds, by a sufficient
+ * margin, the size of the region that the available physical
+ * memory spans, randomize the linear region as well.
+ */
+ if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
+ range /= ARM64_MEMSTART_ALIGN;
+ memstart_addr -= ARM64_MEMSTART_ALIGN *
+ ((range * memstart_offset_seed) >> 16);
+ }
+ }
+
/*
* Apply the memory limit if it was set. Since the kernel may be loaded
* high up in memory, add back the kernel region that must be accessible
@@ -428,22 +445,6 @@ void __init arm64_memblock_init(void)
}
}
- if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
- extern u16 memstart_offset_seed;
- u64 range = linear_region_size -
- (memblock_end_of_DRAM() - memblock_start_of_DRAM());
-
- /*
- * If the size of the linear region exceeds, by a sufficient
- * margin, the size of the region that the available physical
- * memory spans, randomize the linear region as well.
- */
- if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
- range /= ARM64_MEMSTART_ALIGN;
- memstart_addr -= ARM64_MEMSTART_ALIGN *
- ((range * memstart_offset_seed) >> 16);
- }
- }
/*
* Register the kernel text, kernel data, initrd, and initial
--
2.17.1
