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Subject[PATCH 1/2] x86/boot/KASLR: Add two functions for 1GB huge pages handling
Date
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);
+ }
+}
+
+
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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