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Subject[PATCH v2 7/9] get the random phy addr according to slot_area info
Date
Now random value can be used to get related slot info stored in
slot_area, mainly use slot_area.num to position which slot is target.
With this slot its starting address is returned as the physical
address where kernel will put.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
arch/x86/boot/compressed/aslr.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index 1c6fb31..55adee2 100644
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -245,9 +245,6 @@ static unsigned long mem_min_overlap(struct mem_vector *img, struct mem_vector *
return min;
}

-static unsigned long slots[CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
- CONFIG_PHYSICAL_ALIGN];
-
struct slot_area {
unsigned long addr;
int num;
@@ -261,23 +258,28 @@ static unsigned long slot_max;

static unsigned long slot_area_index;

-static void slots_append(unsigned long addr)
-{
- /* Overflowing the slots list should be impossible. */
- if (slot_max >= CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
- CONFIG_PHYSICAL_ALIGN)
- return;
-
- slots[slot_max++] = addr;
-}
-
static unsigned long slots_fetch_random(void)
{
+ unsigned long random;
+ int i;
+
/* Handle case of no slots stored. */
if (slot_max == 0)
return 0;

- return slots[get_random_long() % slot_max];
+ random = get_random_long() % slot_max;
+
+ for (i=0; i< slot_area_index; i++) {
+ if (random > slot_areas[i].num) {
+ random -= slot_areas[i].num;
+ continue;
+ }
+ return slot_areas[i].addr + random * CONFIG_PHYSICAL_ALIGN;
+ }
+
+ if (i == slot_area_index )
+ debug_putstr("something wrong happened in slots_fetch_random()...\n");
+ return 0;
}

static int process_e820_entry(struct e820entry *entry,
@@ -362,7 +364,7 @@ repeat:
goto repeat;
}

-static unsigned long find_random_addr(unsigned long minimum,
+static unsigned long find_random_phy_addr(unsigned long minimum,
unsigned long size)
{
int i;
@@ -374,6 +376,8 @@ static unsigned long find_random_addr(unsigned long minimum,
/* Verify potential e820 positions, appending to slots list. */
for (i = 0; i < real_mode->e820_entries; i++) {
process_e820_entry(&real_mode->e820_map[i], minimum, size);
+ if ( slot_area_index == MAX_SLOT_AREA )
+ break;
}

return slots_fetch_random();
--
1.9.3


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