Changeset a1b9f63 in mainline for kernel/generic/src/mm/km.c

Timestamp:

2018-08-31T10:32:40Z (7 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

6bf5b8c

Parents:

b1834a01

git-author:

Jakub Jermar <jakub@…> (2018-08-31 09:54:11)

git-committer:

Jakub Jermar <jakub@…> (2018-08-31 10:32:40)

Message:

Add alignment argument to km_map()

km_map() currently always applies alignment requirement equal to the
size of the mapped region. Most of the time, the natural alignment is
unnecessarily strong and especially on 32-bit systems may contribute to
km_map() failures for regions with size in the order of several hundred
megabytes.

This change adds an extra argument to km_map() which allows the caller
to indicate the desired alignment. The old behaviour can be specified
by passing KM_NATURAL_ALIGNMENT as alignment.

This change only adds the alignment argument, but does not change the
alignment requirement anywhere.

File:

• kernel/generic/src/mm/km.c (modified) (4 diffs)

kernel/generic/src/mm/km.c

@@ -130 +130 @@
 
 static uintptr_t
-km_map_aligned(uintptr_t paddr, size_t size, unsigned int flags)
+km_map_aligned(uintptr_t paddr, size_t size, size_t align, unsigned int flags)
 {
         uintptr_t vaddr;
-        size_t align;
         uintptr_t offs;
+
+        if (align == KM_NATURAL_ALIGNMENT)
+                align = ispwr2(size) ? size : (1U << (fnzb(size) + 1));
 
         assert(ALIGN_DOWN(paddr, FRAME_SIZE) == paddr);
         assert(ALIGN_UP(size, FRAME_SIZE) == size);
-
-        /* Enforce natural or at least PAGE_SIZE alignment. */
-        align = ispwr2(size) ? size : (1U << (fnzb(size) + 1));
+        assert(ispwr2(align));
+
+        /* Enforce at least PAGE_SIZE alignment. */
         vaddr = km_page_alloc(size, max(PAGE_SIZE, align));
 
@@ -185 +187 @@
  * @return New virtual address mapped to paddr.
  */
-uintptr_t km_map(uintptr_t paddr, size_t size, unsigned int flags)
+uintptr_t km_map(uintptr_t paddr, size_t size, size_t align, unsigned int flags)
 {
         uintptr_t page;
@@ -192 +194 @@
         offs = paddr - ALIGN_DOWN(paddr, FRAME_SIZE);
         page = km_map_aligned(ALIGN_DOWN(paddr, FRAME_SIZE),
-            ALIGN_UP(size + offs, FRAME_SIZE), flags);
+            ALIGN_UP(size + offs, FRAME_SIZE), align, flags);
 
         return page + offs;
@@ -256 +258 @@
         frame = frame_alloc(1, FRAME_HIGHMEM | FRAME_ATOMIC | flags, 0);
         if (frame) {
-                page = km_map(frame, PAGE_SIZE,
+                page = km_map(frame, PAGE_SIZE, PAGE_SIZE,
                     PAGE_READ | PAGE_WRITE | PAGE_CACHEABLE);
                 if (!page) {