[U-Boot] [PATCH v3 4/7] 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>
---
 include/efi_loader.h          |  2 ++
 lib/efi_loader/efi_boottime.c |  6 +++---
 lib/efi_loader/efi_memory.c   | 40 +++++++++++++++++++++++++++++++++++++++-
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 40e7beb..341d4a4 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -122,6 +122,8 @@ efi_status_t efi_free_pages(uint64_t memory, unsigned long pages);
 /* EFI memory allocator for small allocations, called by EFI payloads */
 efi_status_t efi_allocate_pool(int pool_type, unsigned long size,
 			       void **buffer);
+/* EFI pool memory free function. */
+efi_status_t efi_free_pool(void *buffer);
 /* Returns the EFI memory map */
 efi_status_t efi_get_memory_map(unsigned long *memory_map_size,
 				struct efi_mem_desc *memory_map,
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index eb74cb0..8274d8e 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -141,12 +141,12 @@ static efi_status_t EFIAPI efi_allocate_pool_ext(int pool_type,
 	return EFI_EXIT(r);
 }
 
-static efi_status_t EFIAPI efi_free_pool(void *buffer)
+static efi_status_t EFIAPI efi_free_pool_ext(void *buffer)
 {
 	efi_status_t r;
 
 	EFI_ENTRY("%p", buffer);
-	r = efi_free_pages((ulong)buffer, 0);
+	r = efi_free_pool(buffer);
 	return EFI_EXIT(r);
 }
 
@@ -736,7 +736,7 @@ static const struct efi_boot_services efi_boot_services = {
 	.free_pages = efi_free_pages_ext,
 	.get_memory_map = efi_get_memory_map_ext,
 	.allocate_pool = efi_allocate_pool_ext,
-	.free_pool = efi_free_pool,
+	.free_pool = efi_free_pool_ext,
 	.create_event = efi_create_event,
 	.set_timer = efi_set_timer,
 	.wait_for_event = efi_wait_for_event,
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index 045558d..fa5c639 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -34,6 +34,18 @@ void *efi_bounce_buffer;
 #endif
 
 /*
+ * U-Boot services each EFI AllocatePool request as a separate
+ * (multiple) page allocation.  We have to track the number of pages
+ * to be able to free the correct amount later.
+ * EFI requires 8 byte alignement for pool allocations, so it is
+ * possible to reserve some headroom and serve the remainder.
+ */
+struct efi_pool_allocation {
+	u64 num_pages;
+	char data[];
+};
+
+/*
  * Sorts the memory list from highest address to lowest address
  *
  * When allocating memory we should always start from the highest
@@ -332,9 +344,35 @@ efi_status_t efi_allocate_pool(int pool_type, unsigned long size,
 {
 	efi_status_t r;
 	efi_physical_addr_t t;
-	u64 num_pages = (size + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
+	u64 num_pages = (size + sizeof(u64) + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
+
+	if (size == 0) {
+		*buffer = NULL;
+		return EFI_EXIT(EFI_SUCCESS);
+	}
 
 	r = efi_allocate_pages(0, pool_type, num_pages, &t);
+
+	if (r == EFI_SUCCESS) {
+		struct efi_pool_allocation *alloc = (void *)(uintptr_t)t;
+		alloc->num_pages = num_pages;
+		*buffer = &(alloc->data);
+		assert(((uintptr_t)(*buffer) & 0x7) == 0);
+	}
+
+	return EFI_EXIT(r);
+}
+
+efi_status_t efi_free_pool(void *buffer)
+{
+	efi_status_t r;
+	struct efi_pool_allocation *alloc;
+
+	alloc = container_of(buffer, struct efi_pool_allocation, data);
+	assert(((uintptr_t)alloc & EFI_PAGE_MASK) == 0);
+
+	r = efi_free_pages((uintptr_t)alloc, alloc->num_pages);
+
 	return EFI_EXIT(r);
 }
 
-- 
2.10.0