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path: root/drivers/firmware/efi/libstub/alignedmem.c
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Diffstat (limited to 'drivers/firmware/efi/libstub/alignedmem.c')
-rw-r--r--drivers/firmware/efi/libstub/alignedmem.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/alignedmem.c b/drivers/firmware/efi/libstub/alignedmem.c
new file mode 100644
index 000000000..1de9878dd
--- /dev/null
+++ b/drivers/firmware/efi/libstub/alignedmem.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+/**
+ * efi_allocate_pages_aligned() - Allocate memory pages
+ * @size: minimum number of bytes to allocate
+ * @addr: On return the address of the first allocated page. The first
+ * allocated page has alignment EFI_ALLOC_ALIGN which is an
+ * architecture dependent multiple of the page size.
+ * @max: the address that the last allocated memory page shall not
+ * exceed
+ * @align: minimum alignment of the base of the allocation
+ *
+ * Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
+ * to @align, which should be >= EFI_ALLOC_ALIGN. The last allocated page will
+ * not exceed the address given by @max.
+ *
+ * Return: status code
+ */
+efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
+ unsigned long max, unsigned long align)
+{
+ efi_physical_addr_t alloc_addr;
+ efi_status_t status;
+ int slack;
+
+ if (align < EFI_ALLOC_ALIGN)
+ align = EFI_ALLOC_ALIGN;
+
+ alloc_addr = ALIGN_DOWN(max + 1, align) - 1;
+ size = round_up(size, EFI_ALLOC_ALIGN);
+ slack = align / EFI_PAGE_SIZE - 1;
+
+ status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
+ EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,
+ &alloc_addr);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ *addr = ALIGN((unsigned long)alloc_addr, align);
+
+ if (slack > 0) {
+ int l = (alloc_addr & (align - 1)) / EFI_PAGE_SIZE;
+
+ if (l) {
+ efi_bs_call(free_pages, alloc_addr, slack - l + 1);
+ slack = l - 1;
+ }
+ if (slack)
+ efi_bs_call(free_pages, *addr + size, slack);
+ }
+ return EFI_SUCCESS;
+}