[U-Boot] [PATCH 3/6] efi_loader: Track size of pool allocations to allow freeing

[Stefan Brüns]

allocate_pool has to return a buffer which is 8-byte aligned. Shift the
region returned by allocate_pages by 8 byte and store the size in the
headroom. The 8 byte overhead is neglegible, but provides the required
size when freeing the allocation later.

Signed-off-by: Stefan Brüns <stefan.bruens at rwth-aachen.de>
---
 lib/efi_loader/efi_boottime.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index be6f5e8..3e526eb 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -134,18 +134,35 @@ static efi_status_t EFIAPI efi_allocate_pool(int pool_type, unsigned long size,
 					     void **buffer)
 {
 	efi_status_t r;
+	u64 num_pages = (size + 8 + 0xfff) >> 12;
 
 	EFI_ENTRY("%d, %ld, %p", pool_type, size, buffer);
-	r = efi_allocate_pages(0, pool_type, (size + 0xfff) >> 12, (void*)buffer);
+
+	if (size == 0) {
+		*buffer = NULL;
+		return EFI_EXIT(EFI_SUCCESS);
+	}
+
+	r = efi_allocate_pages(0, pool_type, num_pages, (void *)buffer);
+	if (r == EFI_SUCCESS) {
+		*(u64 *)(*buffer) = num_pages;
+		*buffer = (char *)(*buffer) + 8;
+	}
+
 	return EFI_EXIT(r);
 }
 
 static efi_status_t EFIAPI efi_free_pool(void *buffer)
 {
 	efi_status_t r;
+	u64 num_pages;
 
 	EFI_ENTRY("%p", buffer);
-	r = efi_free_pages((ulong)buffer, 0);
+
+	buffer = (char *)(buffer) - 8;
+	num_pages = *(u64 *)buffer;
+
+	r = efi_free_pages((ulong)buffer, num_pages);
 	return EFI_EXIT(r);
 }
 
-- 
2.10.0