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SubjectRe: [PATCH 1/2] x86/boot/KASLR: Add two functions for 1GB huge pages handling
On Wed, 16. May 18:05, Baoquan He wrote:
> Functions parse_gb_huge_pages() and process_gb_huge_page() are introduced to
> handle conflict between KASLR and huge pages, will be used in the next patch.
>
> Function parse_gb_huge_pages() is used to parse kernel command-line to get
> how many 1GB huge pages have been specified. A static global variable
> 'max_gb_huge_pages' is added to store the number.
>
> And process_gb_huge_page() is used to skip as many 1GB huge pages as possible
> from the passed in memory region according to the specified number.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> arch/x86/boot/compressed/kaslr.c | 71 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 71 insertions(+)
>
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index a0a50b91ecef..13bd879cdc5d 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -215,6 +215,32 @@ static void mem_avoid_memmap(char *str)
> memmap_too_large = true;
> }
>
> +/* Store the number of 1GB huge pages which user specified.*/
> +static unsigned long max_gb_huge_pages;
> +
> +static int parse_gb_huge_pages(char *param, char* val)
> +{
> + char *p;
> + u64 mem_size;
> + static bool gbpage_sz = false;
> +
> + if (!strcmp(param, "hugepagesz")) {
> + p = val;
> + mem_size = memparse(p, &p);
> + if (mem_size == PUD_SIZE) {
> + if (gbpage_sz)
> + warn("Repeadly set hugeTLB page size of 1G!\n");
> + gbpage_sz = true;
> + } else
> + gbpage_sz = false;
> + } else if (!strcmp(param, "hugepages") && gbpage_sz) {
> + p = val;
> + max_gb_huge_pages = simple_strtoull(p, &p, 0);
> + debug_putaddr(max_gb_huge_pages);
> + }
> +}
Hello,

the return value is missing for the function or not ?

regards
Damian

> +
> +
> static int handle_mem_memmap(void)
> {
> char *args = (char *)get_cmd_line_ptr();
> @@ -466,6 +492,51 @@ static void store_slot_info(struct mem_vector *region, unsigned long image_size)
> }
> }
>
> +/* Skip as many 1GB huge pages as possible in the passed region. */
> +static void process_gb_huge_page(struct mem_vector *region, unsigned long image_size)
> +{
> + int i = 0;
> + unsigned long addr, size;
> + struct mem_vector tmp;
> +
> + if (!max_gb_huge_pages) {
> + store_slot_info(region, image_size);
> + return;
> + }
> +
> + addr = ALIGN(region->start, PUD_SIZE);
> + /* If Did we raise the address above the passed in memory entry? */
> + if (addr < region->start + region->size)
> + size = region->size - (addr - region->start);
> +
> + /* Check how many 1GB huge pages can be filtered out*/
> + while (size > PUD_SIZE && max_gb_huge_pages) {
> + size -= PUD_SIZE;
> + max_gb_huge_pages--;
> + i++;
> + }
> +
> + if (!i) {
> + store_slot_info(region, image_size);
> + return;
> + }
> +
> + /* Process the remaining regions after filtering out. */
> +
> + if (addr >= region->start + image_size) {
> + tmp.start = region->start;
> + tmp.size = addr - region->start;
> + store_slot_info(&tmp, image_size);
> + }
> +
> + size = region->size - (addr - region->start) - i * PUD_SIZE;
> + if (size >= image_size) {
> + tmp.start = addr + i*PUD_SIZE;
> + tmp.size = size;
> + store_slot_info(&tmp, image_size);
> + }
> +}
> +
> static unsigned long slots_fetch_random(void)
> {
> unsigned long slot;
> --
> 2.13.6
>

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