[PATCH] efi_loader: Fix loaded image alignment

[Ilias Apalodimas]

We are ignoring the alignment communicated via the PE/COFF header.
Starting 5.10 the Linux kernel will loudly complain about it. For more
details look at [1] (in linux kernel).

So add a function that can allocate aligned EFI memory and use it for our
relocated loaded image.

[1] c32ac11da3f83 ("efi/libstub: arm64: Double check image alignment at entry")

Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
 include/efi_loader.h              |  2 ++
 lib/efi_loader/efi_image_loader.c | 12 ++++----
 lib/efi_loader/efi_memory.c       | 50 +++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index c440962fe522..5cdc72345e52 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -675,6 +675,8 @@ struct efi_device_path *efi_get_dp_from_boot(const efi_guid_t guid);
 #define efi_size_in_pages(size) (((size) + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT)
 /* Generic EFI memory allocator, call this to get memory */
 void *efi_alloc(uint64_t len, int memory_type);
+/* 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 */
 efi_status_t efi_allocate_pages(enum efi_allocate_type type,
 				enum efi_memory_type memory_type,
diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
index e9572d4d5dbb..eb95580538cc 100644
--- a/lib/efi_loader/efi_image_loader.c
+++ b/lib/efi_loader/efi_image_loader.c
@@ -898,9 +898,9 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
 		image_base = opt->ImageBase;
 		efi_set_code_and_data_type(loaded_image_info, opt->Subsystem);
 		handle->image_type = opt->Subsystem;
-		virt_size = ALIGN(virt_size, opt->SectionAlignment);
-		efi_reloc = efi_alloc(virt_size,
-				      loaded_image_info->image_code_type);
+		efi_reloc = efi_alloc_aligned_pages(virt_size,
+						    loaded_image_info->image_code_type,
+						    opt->SectionAlignment);
 		if (!efi_reloc) {
 			log_err("Out of memory\n");
 			ret = EFI_OUT_OF_RESOURCES;
@@ -914,9 +914,9 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
 		image_base = opt->ImageBase;
 		efi_set_code_and_data_type(loaded_image_info, opt->Subsystem);
 		handle->image_type = opt->Subsystem;
-		virt_size = ALIGN(virt_size, opt->SectionAlignment);
-		efi_reloc = efi_alloc(virt_size,
-				      loaded_image_info->image_code_type);
+		efi_reloc = efi_alloc_aligned_pages(virt_size,
+						    loaded_image_info->image_code_type,
+						    opt->SectionAlignment);
 		if (!efi_reloc) {
 			log_err("Out of memory\n");
 			ret = EFI_OUT_OF_RESOURCES;
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index f4acbee4f9b6..49d36d369aaa 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -549,6 +549,56 @@ efi_status_t efi_free_pages(uint64_t memory, efi_uintn_t pages)
 	return ret;
 }
 
+/**
+ * efi_alloc_aligned_pages - allocate
+ *
+ * @len		len in bytes
+ * @memory_type	usage type of the allocated memory
+ * @align	alignment in bytes
+ * Return:	aligned memory or NULL
+ */
+void *efi_alloc_aligned_pages(u64 len, int memory_type, size_t align)
+{
+	u64 req_pages = efi_size_in_pages(len);
+	u64 true_pages = req_pages + efi_size_in_pages(align) - 1;
+	u64 free_pages = 0;
+	u64 aligned_mem;
+	efi_status_t r;
+	u64 mem;
+
+	if (align & (align - 1))
+		return NULL;
+
+	if (true_pages < req_pages)
+		return NULL;
+
+	if (align < EFI_PAGE_SIZE) {
+		r = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES, memory_type,
+				       req_pages, &mem);
+		return (r == EFI_SUCCESS) ? (void *)mem : NULL;
+	}
+
+	r = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES, memory_type,
+			       true_pages, &mem);
+	if (r != EFI_SUCCESS)
+		return NULL;
+
+	aligned_mem = ALIGN(mem, align);
+	/* Free pages before alignment */
+	free_pages = efi_size_in_pages(aligned_mem - mem);
+	if (free_pages)
+		efi_free_pages(mem, free_pages);
+
+	/* Free trailing pages */
+	free_pages = true_pages - (req_pages + free_pages);
+	if (free_pages) {
+		mem = aligned_mem + req_pages * EFI_PAGE_SIZE;
+		efi_free_pages(mem, free_pages);
+	}
+
+	return (void *)aligned_mem;
+}
+
 /**
  * efi_allocate_pool - allocate memory from pool
  *
-- 
2.33.0