[PATCH 6/6] extend the upper limit of kernel physical address randomization to 4G

[Baoquan He]

Since now kaslr can separately do randomization of physical and virtual
address, the physical address doesn't have to be
CONFIG_RANDOMIZE_BASE_MAX_OFFSET any more. At this time the identity
mapping only covers [0, 4G], so extend the upper limit of kernel physical
address randomization to 4G.

Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
 arch/x86/boot/compressed/aslr.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index 20a5f23..b112f90 100644
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -207,14 +207,15 @@ static bool mem_avoid_overlap(struct mem_vector *img)
 	return false;
 }
 
-static unsigned long slots[CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
+#define PHYS_RANDOM_UPPER_LIMIT 0x100000000UL
+static unsigned long slots[PHYS_RANDOM_UPPER_LIMIT /
 			   CONFIG_PHYSICAL_ALIGN];
 static unsigned long slot_max;
 
 static void slots_append(unsigned long addr)
 {
 	/* Overflowing the slots list should be impossible. */
-	if (slot_max >= CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
+	if (slot_max >= PHYS_RANDOM_UPPER_LIMIT /
 			CONFIG_PHYSICAL_ALIGN)
 		return;
 
@@ -241,7 +242,7 @@ static void process_e820_entry(struct e820entry *entry,
 		return;
 
 	/* Ignore entries entirely above our maximum. */
-	if (entry->addr >= CONFIG_RANDOMIZE_BASE_MAX_OFFSET)
+	if (entry->addr >= PHYS_RANDOM_UPPER_LIMIT)
 		return;
 
 	/* Ignore entries entirely below our minimum. */
@@ -266,8 +267,8 @@ static void process_e820_entry(struct e820entry *entry,
 	region.size -= region.start - entry->addr;
 
 	/* Reduce maximum size to fit end of image within maximum limit. */
-	if (region.start + region.size > CONFIG_RANDOMIZE_BASE_MAX_OFFSET)
-		region.size = CONFIG_RANDOMIZE_BASE_MAX_OFFSET - region.start;
+	if (region.start + region.size  > PHYS_RANDOM_UPPER_LIMIT)
+		region.size = PHYS_RANDOM_UPPER_LIMIT - region.start;
 
 	/* Walk each aligned slot and check for avoided areas. */
 	for (img.start = region.start, img.size = image_size ;
-- 
1.9.3

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