arm64/efi: move arm64 specific stub C code to libstub

Now that we added special handling to the C files in libstub, move
the one remaining arm64 specific EFI stub C file to libstub as
well, so that it gets the same treatment. This should prevent future
changes from resulting in binaries that may execute incorrectly in
UEFI context.

With efi-entry.S the only remaining EFI stub source file under
arch/arm64, we can also simplify the Makefile logic somewhat.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2 files changed, 2 insertions, 75 deletions

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 1b6bda2ff102..474691f8b13a 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -4,11 +4,8 @@
 
 CPPFLAGS_vmlinux.lds	:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 AFLAGS_head.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
-CFLAGS_efi-stub.o 	:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 CFLAGS_armv8_deprecated.o := -I$(src)
 
-KASAN_SANITIZE_efi-stub.o	:= n
-
 CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_insn.o = -pg
 CFLAGS_REMOVE_return_address.o = -pg
@@ -22,9 +19,7 @@ arm64-obj-y		:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   cpufeature.o alternative.o cacheinfo.o		\
 			   smp.o smp_spin_table.o topology.o
 
-stub-obj				:= efi-stub.o efi-entry.o
-extra-y					:= $(stub-obj)
-stub-obj				:= $(patsubst %.o,%.stub.o,$(stub-obj))
+extra-$(CONFIG_EFI)			:= efi-entry.o
 
 OBJCOPYFLAGS := --prefix-symbols=__efistub_
 $(obj)/%.stub.o: $(obj)/%.o FORCE
@@ -42,7 +37,7 @@ arm64-obj-$(CONFIG_CPU_PM)		+= sleep.o suspend.o
 arm64-obj-$(CONFIG_CPU_IDLE)		+= cpuidle.o
 arm64-obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
-arm64-obj-$(CONFIG_EFI)			+= efi.o $(stub-obj)
+arm64-obj-$(CONFIG_EFI)			+= efi.o efi-entry.stub.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
deleted file mode 100644
index 816120ece6bc..000000000000
--- a/arch/arm64/kernel/efi-stub.c
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Copyright (C) 2013, 2014 Linaro Ltd;  <roy.franz@linaro.org>
- *
- * This file implements the EFI boot stub for the arm64 kernel.
- * Adapted from ARM version by Mark Salter <msalter@redhat.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- */
-#include <linux/efi.h>
-#include <asm/efi.h>
-#include <asm/sections.h>
-
-efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
-					unsigned long *image_addr,
-					unsigned long *image_size,
-					unsigned long *reserve_addr,
-					unsigned long *reserve_size,
-					unsigned long dram_base,
-					efi_loaded_image_t *image)
-{
-	efi_status_t status;
-	unsigned long kernel_size, kernel_memsize = 0;
-	unsigned long nr_pages;
-	void *old_image_addr = (void *)*image_addr;
-
-	/* Relocate the image, if required. */
-	kernel_size = _edata - _text;
-	if (*image_addr != (dram_base + TEXT_OFFSET)) {
-		kernel_memsize = kernel_size + (_end - _edata);
-
-		/*
-		 * First, try a straight allocation at the preferred offset.
-		 * This will work around the issue where, if dram_base == 0x0,
-		 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
-		 * address of the allocation to be mistaken for a FAIL return
-		 * value or a NULL pointer). It will also ensure that, on
-		 * platforms where the [dram_base, dram_base + TEXT_OFFSET)
-		 * interval is partially occupied by the firmware (like on APM
-		 * Mustang), we can still place the kernel at the address
-		 * 'dram_base + TEXT_OFFSET'.
-		 */
-		*image_addr = *reserve_addr = dram_base + TEXT_OFFSET;
-		nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
-			   EFI_PAGE_SIZE;
-		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
-					EFI_LOADER_DATA, nr_pages,
-					(efi_physical_addr_t *)reserve_addr);
-		if (status != EFI_SUCCESS) {
-			kernel_memsize += TEXT_OFFSET;
-			status = efi_low_alloc(sys_table_arg, kernel_memsize,
-					       SZ_2M, reserve_addr);
-
-			if (status != EFI_SUCCESS) {
-				pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
-				return status;
-			}
-			*image_addr = *reserve_addr + TEXT_OFFSET;
-		}
-		memcpy((void *)*image_addr, old_image_addr, kernel_size);
-		*reserve_size = kernel_memsize;
-	}
-
-
-	return EFI_SUCCESS;
-}