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arm64: move early boot code to the .init segment

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Apart from the arm64/linux and EFI header data structures, there is nothing
in the .head.text section that must reside at the beginning of the Image.
So let's move it to the .init section where it belongs.

Note that this involves some minor tweaking of the EFI header, primarily
because the address of 'stext' no longer coincides with the start of the
.text section. It also requires a couple of relocated symbol references
to be slightly rewritten or their definition moved to the linker script.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-03-30 17:43:07 +02:00 committed by Will Deacon
parent 2c09ec06bc
commit 546c8c44f0
3 changed files with 20 additions and 18 deletions
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2
arch/arm64/kernel/efi-entry.S
View File

@ -62,7 +62,7 @@ ENTRY(entry)
*/
mov x20, x0 // DTB address
ldr x0, [sp, #16] // relocated _text address
movz x21, #:abs_g0:stext_offset
ldr w21, =stext_offset
add x21, x0, x21
/*

32
arch/arm64/kernel/head.S
View File

@ -102,8 +102,6 @@ _head:
#endif
#ifdef CONFIG_EFI
.globl __efistub_stext_offset
.set __efistub_stext_offset, stext - _head
.align 3
pe_header:
.ascii "PE"
@ -123,11 +121,11 @@ optional_header:
.short 0x20b // PE32+ format
.byte 0x02 // MajorLinkerVersion
.byte 0x14 // MinorLinkerVersion
.long _end - stext // SizeOfCode
.long _end - efi_header_end // SizeOfCode
.long 0 // SizeOfInitializedData
.long 0 // SizeOfUninitializedData
.long __efistub_entry - _head // AddressOfEntryPoint
.long __efistub_stext_offset // BaseOfCode
.long efi_header_end - _head // BaseOfCode
extra_header_fields:
.quad 0 // ImageBase
@ -144,7 +142,7 @@ extra_header_fields:
.long _end - _head // SizeOfImage
// Everything before the kernel image is considered part of the header
.long __efistub_stext_offset // SizeOfHeaders
.long efi_header_end - _head // SizeOfHeaders
.long 0 // CheckSum
.short 0xa // Subsystem (EFI application)
.short 0 // DllCharacteristics
@ -188,10 +186,10 @@ section_table:
.byte 0
.byte 0
.byte 0 // end of 0 padding of section name
.long _end - stext // VirtualSize
.long __efistub_stext_offset // VirtualAddress
.long _edata - stext // SizeOfRawData
.long __efistub_stext_offset // PointerToRawData
.long _end - efi_header_end // VirtualSize
.long efi_header_end - _head // VirtualAddress
.long _edata - efi_header_end // SizeOfRawData
.long efi_header_end - _head // PointerToRawData
.long 0 // PointerToRelocations (0 for executables)
.long 0 // PointerToLineNumbers (0 for executables)
@ -200,15 +198,18 @@ section_table:
.long 0xe0500020 // Characteristics (section flags)
/*
* EFI will load stext onwards at the 4k section alignment
* EFI will load .text onwards at the 4k section alignment
* described in the PE/COFF header. To ensure that instruction
* sequences using an adrp and a :lo12: immediate will function
* correctly at this alignment, we must ensure that stext is
* correctly at this alignment, we must ensure that .text is
* placed at a 4k boundary in the Image to begin with.
*/
.align 12
efi_header_end:
#endif
__INIT
ENTRY(stext)
bl preserve_boot_args
bl el2_setup // Drop to EL1, w20=cpu_boot_mode
@ -223,12 +224,12 @@ ENTRY(stext)
* the TCR will have been set.
*/
ldr x27, 0f // address to jump to after
// MMU has been enabled
neg x27, x27 // MMU has been enabled
adr_l lr, __enable_mmu // return (PIC) address
b __cpu_setup // initialise processor
ENDPROC(stext)
.align 3
0: .quad __mmap_switched - (_head - TEXT_OFFSET) + KIMAGE_VADDR
0: .quad (_text - TEXT_OFFSET) - __mmap_switched - KIMAGE_VADDR
/*
* Preserve the arguments passed by the bootloader in x0 .. x3
@ -397,7 +398,7 @@ __create_page_tables:
ldr x5, =KIMAGE_VADDR
add x5, x5, x23 // add KASLR displacement
create_pgd_entry x0, x5, x3, x6
ldr w6, kernel_img_size
ldr w6, =kernel_img_size
add x6, x6, x5
mov x3, x24 // phys offset
create_block_map x0, x7, x3, x5, x6
@ -414,9 +415,6 @@ __create_page_tables:
ret x28
ENDPROC(__create_page_tables)
kernel_img_size:
.long _end - (_head - TEXT_OFFSET)
.ltorg
/*

4
arch/arm64/kernel/image.h
View File

@ -71,8 +71,12 @@
DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET); \
DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);
kernel_img_size = _end - (_text - TEXT_OFFSET);
#ifdef CONFIG_EFI
__efistub_stext_offset = stext - _text;
/*
* Prevent the symbol aliases below from being emitted into the kallsyms
* table, by forcing them to be absolute symbols (which are conveniently