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x86/boot/KASLR: Add two new functions for 1GB huge pages handling

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Introduce two new functions: parse_gb_huge_pages() and process_gb_huge_pages(),
which handle a conflict between KASLR and huge pages of 1GB.

These two functions will be used in the next patch:

- 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.

- process_gb_huge_pages() 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>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: douly.fnst@cn.fujitsu.com
Cc: fanc.fnst@cn.fujitsu.com
Cc: indou.takao@jp.fujitsu.com
Cc: keescook@chromium.org
Cc: lcapitulino@redhat.com
Cc: yasu.isimatu@gmail.com
Link: http://lkml.kernel.org/r/20180625031656.12443-2-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Baoquan He 2018-06-25 11:16:55 +08:00 committed by Ingo Molnar
parent 021c91791a
commit 9b912485e0
1 changed files with 83 additions and 0 deletions
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83
arch/x86/boot/compressed/kaslr.c
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@ -215,6 +215,35 @@ static void mem_avoid_memmap(char *str)
memmap_too_large = true;
}
/* Store the number of 1GB huge pages which users specified: */
static unsigned long max_gb_huge_pages;
static void parse_gb_huge_pages(char *param, char *val)
{
static bool gbpage_sz;
char *p;
if (!strcmp(param, "hugepagesz")) {
p = val;
if (memparse(p, &p) != PUD_SIZE) {
gbpage_sz = false;
return;
}
if (gbpage_sz)
warn("Repeatedly set hugeTLB page size of 1G!\n");
gbpage_sz = true;
return;
}
if (!strcmp(param, "hugepages") && gbpage_sz) {
p = val;
max_gb_huge_pages = simple_strtoull(p, &p, 0);
return;
}
}
static int handle_mem_memmap(void)
{
char *args = (char *)get_cmd_line_ptr();
@ -466,6 +495,60 @@ 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
* according to the number which users specified:
*/
static void
process_gb_huge_pages(struct mem_vector *region, unsigned long image_size)
{
unsigned long addr, size = 0;
struct mem_vector tmp;
int i = 0;
if (!max_gb_huge_pages) {
store_slot_info(region, image_size);
return;
}
addr = ALIGN(region->start, PUD_SIZE);
/* 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++;
}
/* No good 1GB huge pages found: */
if (!i) {
store_slot_info(region, image_size);
return;
}
/*
* Skip those 'i'*1GB good huge pages, and continue checking and
* processing the remaining head or tail part of the passed region
* if available.
*/
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;