From: Peter Feiner <pfeiner@xxxxxxxxxx>
Need this for testing huge pages.
Change-Id: Iecf4f916a3d3d24844957dcd4e81c8aa10b1cdda
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
lib/x86/vm.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
lib/x86/vm.h | 1 +
2 files changed, 58 insertions(+)
diff --git a/lib/x86/vm.c b/lib/x86/vm.c
index 8bd0c88e141e..438ab9c70ffa 100644
--- a/lib/x86/vm.c
+++ b/lib/x86/vm.c
@@ -45,6 +45,63 @@ void *alloc_page()
return p;
}
+/*
+ * Allocates (1 << order) physically contiguous and naturally aligned pages.
+ * Returns NULL if there's no memory left.
+ */
+void *alloc_pages(unsigned long order)
+{
+ /* Generic list traversal. */
+ void *prev;
+ void *curr = NULL;
+ void *next = free;
+
+ /* Looking for a run of length (1 << order). */
+ unsigned long run = 0;
+ const unsigned long n = 1ul << order;
+ const unsigned long align_mask = (n << PAGE_SHIFT) - 1;
+ void *run_start = NULL;
+ void *run_prev = NULL;
+ unsigned long run_next_pa = 0;
+ unsigned long pa;
+
+ assert(order < sizeof(unsigned long) * 8);
+
+ for (;;) {
+ prev = curr;
+ curr = next;
+ next = curr ? *((void **) curr) : NULL;
+
+ if (!curr)
+ return 0;
+
+ pa = virt_to_phys(curr);
+
+ if (run == 0) {
+ if (!(pa & align_mask)) {
+ run_start = curr;
+ run_prev = prev;
+ run_next_pa = pa + PAGE_SIZE;
+ run = 1;
+ }
+ } else if (pa == run_next_pa) {
+ run_next_pa += PAGE_SIZE;
+ run += 1;
+ } else {
+ run = 0;
+ }
+
+ if (run == n) {
+ if (run_prev)
+ *((void **) run_prev) = next;
+ else
+ free = next;
+ return run_start;
+ }
+ }
+}
+
+
void free_page(void *page)
{
*(void **)page = free;
diff --git a/lib/x86/vm.h b/lib/x86/vm.h
index 6a4384f5a48d..64e4b566333f 100644
--- a/lib/x86/vm.h
+++ b/lib/x86/vm.h
@@ -22,6 +22,7 @@ unsigned long *install_pte(unsigned long *cr3,
unsigned long *pt_page);
void *alloc_page();
+void *alloc_pages(unsigned long order);
void free_page(void *page);
unsigned long *install_large_page(unsigned long *cr3,unsigned long phys,
--
2.12.2.816.g2cccc81164-goog
