[PATCH 5/5] efi/arm64: Drop build and linker script hacks to obtain image code size

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

Instead of taking vmlinux symbol values at build time and poking them
into the zboot linker script, wire up struct efi_image_info so this
information can be obtained from the code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/boot/Makefile                  |  3 ---
 arch/arm64/include/asm/efi.h              | 11 ++++++++---
 arch/arm64/kernel/image-vars.h            |  4 ----
 drivers/firmware/efi/libstub/arm64-stub.c |  2 ++
 drivers/firmware/efi/libstub/arm64.c      |  4 +---
 drivers/firmware/efi/libstub/zboot.lds    |  7 -------
 6 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile
index d42d07667822..509b59518818 100644
--- a/arch/arm64/boot/Makefile
+++ b/arch/arm64/boot/Makefile
@@ -51,7 +51,4 @@ EFI_ZBOOT_BFD_TARGET	:= elf64-littleaarch64
 EFI_ZBOOT_MACH_TYPE	:= ARM64
 EFI_ZBOOT_FORWARD_CFI	:= $(CONFIG_ARM64_BTI_KERNEL)
 
-EFI_ZBOOT_OBJCOPY_FLAGS	= --add-symbol zboot_code_size=0x$$( \
-				$(NM) vmlinux|grep _kernel_codesize|cut -d' ' -f1)
-
 include $(srctree)/drivers/firmware/efi/libstub/Makefile.zboot
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index b0c9120b9741..3194e133a4d5 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -151,10 +151,15 @@ efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f);
 
 void efi_icache_sync(unsigned long start, unsigned long end);
 
-// temporary resolution for efistub_get_code_size()
-#define efistub_get_code_size(image_info) ({ extern u32 code_size; code_size; })
-
 struct efi_image_info {
+	s32 _text_offset;
+	s32 __inittext_end_offset;
 };
 
+static inline u32 efistub_get_code_size(const struct efi_image_info *info)
+{
+	return info->__inittext_end_offset - info->_text_offset;
+}
+#define efistub_get_code_size efistub_get_code_size
+
 #endif /* _ASM_EFI_H */
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 19d602e45523..b02234f080b0 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -150,10 +150,6 @@ KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
 
 #endif /* CONFIG_KVM */
 
-#ifdef CONFIG_EFI_ZBOOT
-_kernel_codesize = ABSOLUTE(__inittext_end - _text);
-#endif
-
 /*
  * LLD will occasionally error out with a '__init_end does not converge' error
  * if INIT_IDMAP_DIR_SIZE is defined in terms of _end, as this results in a
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index 8daed681f97d..754cb2843967 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -68,6 +68,8 @@ asm("	.section \".rodata\", \"a\", %progbits;			" \
     "	.align	3;						" \
     "	.globl	efi_image_info;					" \
     "efi_image_info:						" \
+    "	.long	_text - efi_image_info;				" \
+    "	.long	__inittext_end - efi_image_info;		" \
     "	.previous						");
 
 
diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
index 190cf180bb23..da6fa2f6c821 100644
--- a/drivers/firmware/efi/libstub/arm64.c
+++ b/drivers/firmware/efi/libstub/arm64.c
@@ -88,8 +88,6 @@ efi_status_t check_platform_features(void)
 #define DCTYPE	"cvau"
 #endif
 
-u32 __weak code_size;
-
 void efi_cache_sync_image(unsigned long image_base,
 			  unsigned long alloc_size)
 {
@@ -100,7 +98,7 @@ void efi_cache_sync_image(unsigned long image_base,
 	/* only perform the cache maintenance if needed for I/D coherency */
 	if (!(ctr & BIT(CTR_EL0_IDC_SHIFT))) {
 		unsigned long base = image_base;
-		unsigned long size = code_size;
+		unsigned long size = alloc_size;
 
 		do {
 			asm("dc " DCTYPE ", %0" :: "r"(base));
diff --git a/drivers/firmware/efi/libstub/zboot.lds b/drivers/firmware/efi/libstub/zboot.lds
index 367907eb7d86..61714a151766 100644
--- a/drivers/firmware/efi/libstub/zboot.lds
+++ b/drivers/firmware/efi/libstub/zboot.lds
@@ -2,8 +2,6 @@
 
 ENTRY(__efistub_efi_zboot_header);
 
-PROVIDE(zboot_code_size = ABSOLUTE(0));
-
 SECTIONS
 {
 	.head : ALIGN(4096) {
@@ -20,11 +18,6 @@ SECTIONS
 		__efistub_payload_size = . - 4;
 		__efistub__gzdata_end = .;
 		*(.rodata* .init.rodata* .srodata*)
-
-		. = ALIGN(4);
-		__efistub_code_size = .;
-		LONG(zboot_code_size);
-
 		_etext = ALIGN(4096);
 		. = _etext;
 	}
-- 
2.56.0.455.g6c5a503b38-goog