arm64: get rid of TEXT_OFFSET

TEXT_OFFSET serves no purpose, and for this reason, it was redefined
as 0x0 in the v5.8 timeframe. Since this does not appear to have caused
any issues that require us to revisit that decision, let's get rid of the
macro entirely, along with any references to it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20200825135440.11288-1-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

Author: ardbiesheuvel

arch/arm64/Makefile

@@ -11,7 +11,6 @@
 # Copyright (C) 1995-2001 by Russell King
 
 LDFLAGS_vmlinux	:=--no-undefined -X
-CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 ifeq ($(CONFIG_RELOCATABLE), y)
 # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
@@ -132,9 +131,6 @@ endif
 # Default value
 head-y		:= arch/arm64/kernel/head.o
 
-# The byte offset of the kernel image in RAM from the start of RAM.
-TEXT_OFFSET := 0x0
-
 ifeq ($(CONFIG_KASAN_SW_TAGS), y)
 KASAN_SHADOW_SCALE_SHIFT := 4
 else
@@ -145,8 +141,6 @@ KBUILD_CFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 KBUILD_CPPFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 
-export	TEXT_OFFSET
-
 core-y		+= arch/arm64/
 libs-y		:= arch/arm64/lib/ $(libs-y)
 libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a

arch/arm64/include/asm/boot.h

@@ -13,8 +13,7 @@
 #define MAX_FDT_SIZE		SZ_2M
 
 /*
- * arm64 requires the kernel image to placed
- * TEXT_OFFSET bytes beyond a 2 MB aligned base
+ * arm64 requires the kernel image to placed at a 2 MB aligned base address
  */
 #define MIN_KIMG_ALIGN		SZ_2M
 

arch/arm64/include/asm/kernel-pgtable.h

@@ -86,7 +86,7 @@
 			+ EARLY_PGDS((vstart), (vend)) 	/* each PGDIR needs a next level page table */	\
 			+ EARLY_PUDS((vstart), (vend))	/* each PUD needs a next level page table */	\
 			+ EARLY_PMDS((vstart), (vend)))	/* each PMD needs a next level page table */
-#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR + TEXT_OFFSET, _end))
+#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end))
 #define IDMAP_DIR_SIZE		(IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
 
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN

arch/arm64/include/asm/memory.h

@@ -169,7 +169,7 @@ extern s64			memstart_addr;
 /* PHYS_OFFSET - the physical address of the start of memory. */
 #define PHYS_OFFSET		({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })
 
-/* the virtual base of the kernel image (minus TEXT_OFFSET) */
+/* the virtual base of the kernel image */
 extern u64			kimage_vaddr;
 
 /* the offset between the kernel virtual and physical mappings */

arch/arm64/kernel/Makefile

@@ -3,8 +3,6 @@
 # Makefile for the linux kernel.
 #
 
-CPPFLAGS_vmlinux.lds	:= -DTEXT_OFFSET=$(TEXT_OFFSET)
-AFLAGS_head.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 CFLAGS_armv8_deprecated.o := -I$(src)
 
 CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)

arch/arm64/kernel/head.S

@@ -36,14 +36,10 @@
 
 #include "efi-header.S"
 
-#define __PHYS_OFFSET	(KERNEL_START - TEXT_OFFSET)
+#define __PHYS_OFFSET	KERNEL_START
 
-#if (TEXT_OFFSET & 0xfff) != 0
-#error TEXT_OFFSET must be at least 4KB aligned
-#elif (PAGE_OFFSET & 0x1fffff) != 0
+#if (PAGE_OFFSET & 0x1fffff) != 0
 #error PAGE_OFFSET must be at least 2MB aligned
-#elif TEXT_OFFSET > 0x1fffff
-#error TEXT_OFFSET must be less than 2MB
 #endif
 
 /*
@@ -55,7 +51,7 @@
  *   x0 = physical address to the FDT blob.
  *
  * This code is mostly position independent so you call this at
- * __pa(PAGE_OFFSET + TEXT_OFFSET).
+ * __pa(PAGE_OFFSET).
  *
  * Note that the callee-saved registers are used for storing variables
  * that are useful before the MMU is enabled. The allocations are described
@@ -77,7 +73,7 @@ _head:
 	b	primary_entry			// branch to kernel start, magic
 	.long	0				// reserved
 #endif
-	le64sym	_kernel_offset_le		// Image load offset from start of RAM, little-endian
+	.quad	0				// Image load offset from start of RAM, little-endian
 	le64sym	_kernel_size_le			// Effective size of kernel image, little-endian
 	le64sym	_kernel_flags_le		// Informative flags, little-endian
 	.quad	0				// reserved
@@ -382,7 +378,7 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
 	 * Map the kernel image (starting with PHYS_OFFSET).
 	 */
 	adrp	x0, init_pg_dir
-	mov_q	x5, KIMAGE_VADDR + TEXT_OFFSET	// compile time __va(_text)
+	mov_q	x5, KIMAGE_VADDR		// compile time __va(_text)
 	add	x5, x5, x23			// add KASLR displacement
 	mov	x4, PTRS_PER_PGD
 	adrp	x6, _end			// runtime __pa(_end)
@@ -474,7 +470,7 @@ SYM_FUNC_END(__primary_switched)
 
 	.pushsection ".rodata", "a"
 SYM_DATA_START(kimage_vaddr)
-	.quad		_text - TEXT_OFFSET
+	.quad		_text
 SYM_DATA_END(kimage_vaddr)
 EXPORT_SYMBOL(kimage_vaddr)
 	.popsection

arch/arm64/kernel/image.h

@@ -62,7 +62,6 @@
  */
 #define HEAD_SYMBOLS						\
 	DEFINE_IMAGE_LE64(_kernel_size_le, _end - _text);	\
-	DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET);	\
 	DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);
 
 #endif /* __ARM64_KERNEL_IMAGE_H */

arch/arm64/kernel/vmlinux.lds.S

@@ -105,7 +105,7 @@ SECTIONS
 		*(.eh_frame)
 	}
 
-	. = KIMAGE_VADDR + TEXT_OFFSET;
+	. = KIMAGE_VADDR;
 
 	.head.text : {
 		_text = .;
@@ -274,4 +274,4 @@ ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE,
 /*
  * If padding is applied before .head.text, virt<->phys conversions will fail.
  */
-ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned")
+ASSERT(_text == KIMAGE_VADDR, "HEAD is misaligned")

drivers/firmware/efi/libstub/Makefile

@@ -64,7 +64,6 @@ lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= arm64-stub.o
 lib-$(CONFIG_X86)		+= x86-stub.o
 CFLAGS_arm32-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
-CFLAGS_arm64-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 #
 # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the

drivers/firmware/efi/libstub/arm64-stub.c

@@ -77,7 +77,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 
 	kernel_size = _edata - _text;
 	kernel_memsize = kernel_size + (_end - _edata);
-	*reserve_size = kernel_memsize + TEXT_OFFSET % min_kimg_align();
+	*reserve_size = kernel_memsize;
 
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
 		/*
@@ -91,7 +91,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	}
 
 	if (status != EFI_SUCCESS) {
-		if (IS_ALIGNED((u64)_text - TEXT_OFFSET, min_kimg_align())) {
+		if (IS_ALIGNED((u64)_text, min_kimg_align())) {
 			/*
 			 * Just execute from wherever we were loaded by the
 			 * UEFI PE/COFF loader if the alignment is suitable.
@@ -111,7 +111,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		}
 	}
 
-	*image_addr = *reserve_addr + TEXT_OFFSET % min_kimg_align();
+	*image_addr = *reserve_addr;
 	memcpy((void *)*image_addr, _text, kernel_size);
 
 	return EFI_SUCCESS;