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

[Baoquan He]

On 06/21/18 at 05:01pm, Ingo Molnar wrote:
> 
> * 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.
> 

Sorry, I will check all of them carefully and repost according to your
comments.

> > +/* 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