linux-xiaomi-chiron/arch/arm64/kernel/vmlinux.lds.S
Ard Biesheuvel 7eb90f2ff7 arm64: cover the .head.text section in the .text segment mapping
Keeping .head.text out of the .text mapping buys us very little: its actual
payload is only 4 KB, most of which is padding, but the page alignment may
add up to 2 MB (in case of CONFIG_DEBUG_ALIGN_RODATA=y) of additional
padding to the uncompressed kernel Image.

Also, on 4 KB granule kernels, the 4 KB misalignment of .text forces us to
map the adjacent 56 KB of code without the PTE_CONT attribute, and since
this region contains things like the vector table and the GIC interrupt
handling entry point, this region is likely to benefit from the reduced TLB
pressure that results from PTE_CONT mappings.

So remove the alignment between the .head.text and .text sections, and use
the [_text, _etext) rather than the [_stext, _etext) interval for mapping
the .text segment.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-04-14 18:11:43 +01:00

207 lines
4.6 KiB
ArmAsm

/*
* ld script to make ARM Linux kernel
* taken from the i386 version by Russell King
* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
*/
#include <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
#include <asm/kernel-pgtable.h>
#include <asm/thread_info.h>
#include <asm/memory.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include "image.h"
/* .exit.text needed in case of alternative patching */
#define ARM_EXIT_KEEP(x) x
#define ARM_EXIT_DISCARD(x)
OUTPUT_ARCH(aarch64)
ENTRY(_text)
jiffies = jiffies_64;
#define HYPERVISOR_TEXT \
/* \
* Align to 4 KB so that \
* a) the HYP vector table is at its minimum \
* alignment of 2048 bytes \
* b) the HYP init code will not cross a page \
* boundary if its size does not exceed \
* 4 KB (see related ASSERT() below) \
*/ \
. = ALIGN(SZ_4K); \
VMLINUX_SYMBOL(__hyp_idmap_text_start) = .; \
*(.hyp.idmap.text) \
VMLINUX_SYMBOL(__hyp_idmap_text_end) = .; \
VMLINUX_SYMBOL(__hyp_text_start) = .; \
*(.hyp.text) \
VMLINUX_SYMBOL(__hyp_text_end) = .;
#define IDMAP_TEXT \
. = ALIGN(SZ_4K); \
VMLINUX_SYMBOL(__idmap_text_start) = .; \
*(.idmap.text) \
VMLINUX_SYMBOL(__idmap_text_end) = .;
/*
* The size of the PE/COFF section that covers the kernel image, which
* runs from stext to _edata, must be a round multiple of the PE/COFF
* FileAlignment, which we set to its minimum value of 0x200. 'stext'
* itself is 4 KB aligned, so padding out _edata to a 0x200 aligned
* boundary should be sufficient.
*/
PECOFF_FILE_ALIGNMENT = 0x200;
#ifdef CONFIG_EFI
#define PECOFF_EDATA_PADDING \
.pecoff_edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGNMENT); }
#else
#define PECOFF_EDATA_PADDING
#endif
#if defined(CONFIG_DEBUG_ALIGN_RODATA)
#define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT);
#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
#elif defined(CONFIG_DEBUG_RODATA)
#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT);
#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
#else
#define ALIGN_DEBUG_RO
#define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min);
#endif
SECTIONS
{
/*
* XXX: The linker does not define how output sections are
* assigned to input sections when there are multiple statements
* matching the same input section name. There is no documented
* order of matching.
*/
/DISCARD/ : {
ARM_EXIT_DISCARD(EXIT_TEXT)
ARM_EXIT_DISCARD(EXIT_DATA)
EXIT_CALL
*(.discard)
*(.discard.*)
*(.interp .dynamic)
}
. = KIMAGE_VADDR + TEXT_OFFSET;
.head.text : {
_text = .;
HEAD_TEXT
}
.text : { /* Real text segment */
_stext = .; /* Text and read-only data */
__exception_text_start = .;
*(.exception.text)
__exception_text_end = .;
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
HYPERVISOR_TEXT
IDMAP_TEXT
*(.fixup)
*(.gnu.warning)
. = ALIGN(16);
*(.got) /* Global offset table */
}
ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
RO_DATA(PAGE_SIZE) /* everything from this point to */
EXCEPTION_TABLE(8) /* _etext will be marked RO NX */
NOTES
ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
_etext = .; /* End of text and rodata section */
__init_begin = .;
INIT_TEXT_SECTION(8)
.exit.text : {
ARM_EXIT_KEEP(EXIT_TEXT)
}
.init.data : {
INIT_DATA
INIT_SETUP(16)
INIT_CALLS
CON_INITCALL
SECURITY_INITCALL
INIT_RAM_FS
*(.init.rodata.* .init.bss) /* from the EFI stub */
}
.exit.data : {
ARM_EXIT_KEEP(EXIT_DATA)
}
PERCPU_SECTION(L1_CACHE_BYTES)
. = ALIGN(4);
.altinstructions : {
__alt_instructions = .;
*(.altinstructions)
__alt_instructions_end = .;
}
.altinstr_replacement : {
*(.altinstr_replacement)
}
.rela : ALIGN(8) {
__reloc_start = .;
*(.rela .rela*)
__reloc_end = .;
}
.dynsym : ALIGN(8) {
__dynsym_start = .;
*(.dynsym)
}
.dynstr : {
*(.dynstr)
}
.hash : {
*(.hash)
}
. = ALIGN(PAGE_SIZE);
__init_end = .;
_data = .;
_sdata = .;
RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
PECOFF_EDATA_PADDING
_edata = .;
BSS_SECTION(0, 0, 0)
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
swapper_pg_dir = .;
. += SWAPPER_DIR_SIZE;
_end = .;
STABS_DEBUG
HEAD_SYMBOLS
}
/*
* The HYP init code and ID map text can't be longer than a page each,
* and should not cross a page boundary.
*/
ASSERT(__hyp_idmap_text_end - (__hyp_idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
"HYP init code too big or misaligned")
ASSERT(__idmap_text_end - (__idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
"ID map text too big or misaligned")
/*
* If padding is applied before .head.text, virt<->phys conversions will fail.
*/
ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned")