lib: efi_loader: efi_memory.c: add efi_realloc() for realloc memory

Add efi_realloc() for realloc memory that previously alloc by efi_alloc().
Note that if realloced memory is explicitly allocated as BootServicesData.

Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Peter Robinson <pbrobinson@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

include/efi_loader.h

@@ -875,6 +875,16 @@ efi_status_t efi_next_variable_name(efi_uintn_t *size, u16 **buf,
 #define efi_size_in_pages(size) (((size) + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT)
 /* Allocate boot service data pool memory */
 void *efi_alloc(size_t len);
+/**
+ * efi_realloc() - reallocate boot services data pool memory
+ *
+ * Reallocate memory from pool for a new size and copy the data from old one.
+ *
+ * @ptr:	pointer to the buffer
+ * @size:	number of bytes to allocate
+ * Return:	EFI status to indicate success or not
+ */
+efi_status_t efi_realloc(void **ptr, size_t len);
 /* Allocate pages on the specified alignment */
 void *efi_alloc_aligned_pages(u64 len, int memory_type, size_t align);
 /* More specific EFI memory allocator, called by EFI payloads */

lib/efi_loader/efi_memory.c

@@ -668,6 +668,64 @@ void *efi_alloc(size_t size)
 	return buf;
 }
 
+/**
+ * efi_realloc() - reallocate boot services data pool memory
+ *
+ * Reallocate memory from pool for a new size and copy the data from old one.
+ *
+ * @ptr:	pointer to old buffer
+ * @size:	number of bytes to allocate
+ * Return:	EFI status to indicate success or not
+ */
+efi_status_t efi_realloc(void **ptr, size_t size)
+{
+	efi_status_t ret;
+	void *new_ptr;
+	struct efi_pool_allocation *alloc;
+	u64 num_pages = efi_size_in_pages(size +
+					  sizeof(struct efi_pool_allocation));
+	size_t old_size;
+
+	if (!*ptr) {
+		*ptr = efi_alloc(size);
+		if (*ptr)
+			return EFI_SUCCESS;
+		return EFI_OUT_OF_RESOURCES;
+	}
+
+	ret = efi_check_allocated((uintptr_t)*ptr, true);
+	if (ret != EFI_SUCCESS)
+		return ret;
+
+	alloc = container_of(*ptr, struct efi_pool_allocation, data);
+
+	/* Check that this memory was allocated by efi_allocate_pool() */
+	if (((uintptr_t)alloc & EFI_PAGE_MASK) ||
+	    alloc->checksum != checksum(alloc)) {
+		printf("%s: illegal realloc 0x%p\n", __func__, *ptr);
+		return EFI_INVALID_PARAMETER;
+	}
+
+	/* Don't realloc. The actual size in pages is the same. */
+	if (alloc->num_pages == num_pages)
+		return EFI_SUCCESS;
+
+	old_size = alloc->num_pages * EFI_PAGE_SIZE -
+		sizeof(struct efi_pool_allocation);
+
+	new_ptr = efi_alloc(size);
+
+	/* copy old data to new alloced buffer */
+	memcpy(new_ptr, *ptr, min(size, old_size));
+
+	/* free the old buffer */
+	efi_free_pool(*ptr);
+
+	*ptr = new_ptr;
+
+	return EFI_SUCCESS;
+}
+
 /**
  * efi_free_pool() - free memory from pool
  *