The number of slots and slot areas can be unsigned int, since on 64-bit, the maximum amount of memory is 2^52, the minimum alignment is 2^21, so the slot number cannot be greater than 2^31. The slot areas are limited by MAX_SLOT_AREA, currently 100. Replace the type used for slot number, which is currently a mix of int and unsigned long, with unsigned int consistently.
Drop unnecessary check that number of slots is not zero in store_slot_info, it's guaranteed to be at least 1 by the calculation. Drop unnecessary alignment of image_size to CONFIG_PHYSICAL_ALIGN in find_random_virt_addr, it cannot change the result: the largest valid slot is the largest n that satisfies minimum + n * CONFIG_PHYSICAL_ALIGN + image_size <= KERNEL_IMAGE_SIZE (since minimum is already aligned) and so n is equal to (KERNEL_IMAGE_SIZE - minimum - image_size) / CONFIG_PHYSICAL_ALIGN even if image_size is not aligned to CONFIG_PHYSICAL_ALIGN. Signed-off-by: Arvind Sankar <[email protected]> --- arch/x86/boot/compressed/kaslr.c | 36 ++++++++++++-------------------- 1 file changed, 13 insertions(+), 23 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 29ec964b1330..ffbcc0444f70 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -511,16 +511,14 @@ static bool mem_avoid_overlap(struct mem_vector *img, struct slot_area { unsigned long addr; - int num; + unsigned 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 unsigned int slot_area_index; +static unsigned int slot_max; static void store_slot_info(struct mem_vector *region, unsigned long image_size) { @@ -530,13 +528,10 @@ static void store_slot_info(struct mem_vector *region, unsigned long image_size) return; slot_area.addr = region->start; - slot_area.num = (region->size - image_size) / - CONFIG_PHYSICAL_ALIGN + 1; + slot_area.num = 1 + (region->size - image_size) / CONFIG_PHYSICAL_ALIGN; - if (slot_area.num > 0) { - slot_areas[slot_area_index++] = slot_area; - slot_max += slot_area.num; - } + slot_areas[slot_area_index++] = slot_area; + slot_max += slot_area.num; } /* @@ -589,8 +584,7 @@ process_gb_huge_pages(struct mem_vector *region, unsigned long image_size) static unsigned long slots_fetch_random(void) { - unsigned long slot; - int i; + unsigned int slot, i; /* Handle case of no slots stored. */ if (slot_max == 0) @@ -603,7 +597,7 @@ static unsigned long slots_fetch_random(void) slot -= slot_areas[i].num; continue; } - return slot_areas[i].addr + slot * CONFIG_PHYSICAL_ALIGN; + return slot_areas[i].addr + (unsigned long)slot * CONFIG_PHYSICAL_ALIGN; } if (i == slot_area_index) @@ -819,28 +813,24 @@ static unsigned long find_random_phys_addr(unsigned long minimum, return 0; } - if (process_efi_entries(minimum, image_size)) - return slots_fetch_random(); + if (!process_efi_entries(minimum, image_size)) + process_e820_entries(minimum, image_size); - process_e820_entries(minimum, image_size); return slots_fetch_random(); } static unsigned long find_random_virt_addr(unsigned long minimum, unsigned long image_size) { - unsigned long slots, random_addr; - - /* Align image_size for easy slot calculations. */ - image_size = ALIGN(image_size, CONFIG_PHYSICAL_ALIGN); + unsigned int slots; + unsigned long random_addr; /* * There are how many CONFIG_PHYSICAL_ALIGN-sized slots * that can hold image_size within the range of minimum to * KERNEL_IMAGE_SIZE? */ - slots = (KERNEL_IMAGE_SIZE - minimum - image_size) / - CONFIG_PHYSICAL_ALIGN + 1; + slots = 1 + (KERNEL_IMAGE_SIZE - minimum - image_size) / CONFIG_PHYSICAL_ALIGN; random_addr = kaslr_get_random_long("Virtual") % slots; -- 2.26.2
