Re: [PATCH 1/2] x86/boot/KASLR: Add two functions for 1GB huge pages handling

From: Ingo Molnar
Date: Thu Jun 21 2018 - 11:01:23 EST



* Baoquan He <bhe@xxxxxxxxxx> wrote:

> +/* 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);
> + }
> +}

This function has at least one style problem and one typo.

Also, we don't put statics in the middle of function variable blocks.

> +/* 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);
> + }
> +}

I counted about 5 style problems and at least one typo in this function ...

Please review the code you are submitting more carefully for small details as
well.

Thanks,

Ingo