Messages in this thread Patch in this message | | | From | Baoquan He <> | Subject | [PATCH v3 13/19] x86, kaslr: Introduce struct slot_area to manage randomization slot info | Date | Sat, 5 Mar 2016 00:25:11 +0800 |
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Kernel is expected to be randomly reloaded anywhere in the whole physical memory area, it could be near 64T at most. In this case there could be about 4*1024*1024 randomization slots if CONFIG_PHYSICAL_ALIGN is 0x1000000. Currently the starting address of candidate position is stored into array slots[], and it finds each available slot one time and save it into slots[]. With this old way the slot arrry will cost too much memory and it's also very unefficient to get and save the slot information into slot array one by one.
Here introduce struct slot_area to manage randomization slot info in one contiguous memory area excluding the avoid area. Each slot_area will contain the starting address and how many available slots in this area. Array slot_areas is used to store all slot area info.
Since setup_data is a linked list, could contain many datas by pointer to point one by one, excluding them will split RAM memory into many smaller areas, here only take the first 100 slot areas if too many of them.
Signed-off-by: Baoquan He <bhe@redhat.com> --- arch/x86/boot/compressed/aslr.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c index 35f2eac..7fc22a6 100644 --- a/arch/x86/boot/compressed/aslr.c +++ b/arch/x86/boot/compressed/aslr.c @@ -216,8 +216,20 @@ static bool mem_avoid_overlap(struct mem_vector *img) static unsigned long slots[CONFIG_RANDOMIZE_BASE_MAX_OFFSET / CONFIG_PHYSICAL_ALIGN]; + +struct slot_area { + unsigned long addr; + int num; +}; + +#define MAX_SLOT_AREA 100 + +static struct slot_area slot_areas[MAX_SLOT_AREA]; + 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. */ -- 2.5.0
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