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

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Date:   Thu, 21 Jun 2018 17:01:11 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Baoquan He <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org, lcapitulino@...hat.com,
        keescook@...omium.org, tglx@...utronix.de, x86@...nel.org,
        hpa@...or.com, fanc.fnst@...fujitsu.com, yasu.isimatu@...il.com,
        indou.takao@...fujitsu.com, douly.fnst@...fujitsu.com
Subject: Re: [PATCH 1/2] x86/boot/KASLR: Add two functions for 1GB huge pages
 handling


* Baoquan He <bhe@...hat.com> 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