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remarkable-linux/arch/arm64/kernel/vmlinux.lds.S
Steve Capper 0370b31e48 arm64: Extend early page table code to allow for larger kernels 
Currently the early assembler page table code assumes that precisely
1xpgd, 1xpud, 1xpmd are sufficient to represent the early kernel text
mappings.

Unfortunately this is rarely the case when running with a 16KB granule,
and we also run into limits with 4KB granule when building much larger
kernels.

This patch re-writes the early page table logic to compute indices of
mappings for each level of page table, and if multiple indices are
required, the next-level page table is scaled up accordingly.

Also the required size of the swapper_pg_dir is computed at link time
to cover the mapping [KIMAGE_ADDR + VOFFSET, _end]. When KASLR is
enabled, an extra page is set aside for each level that may require extra
entries at runtime.

Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-01-14 18:49:52 +00:00

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ArmAsm
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* 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) = .;
#ifdef CONFIG_HIBERNATION
#define HIBERNATE_TEXT \
. = ALIGN(SZ_4K); \
VMLINUX_SYMBOL(__hibernate_exit_text_start) = .;\
*(.hibernate_exit.text) \
VMLINUX_SYMBOL(__hibernate_exit_text_end) = .;
#else
#define HIBERNATE_TEXT
#endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
#define TRAMP_TEXT \
. = ALIGN(PAGE_SIZE); \
VMLINUX_SYMBOL(__entry_tramp_text_start) = .; \
*(.entry.tramp.text) \
. = ALIGN(PAGE_SIZE); \
VMLINUX_SYMBOL(__entry_tramp_text_end) = .;
#else
#define TRAMP_TEXT
#endif
/*
* 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
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)
*(.dynsym .dynstr .hash)
}
. = 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
ENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
HYPERVISOR_TEXT
IDMAP_TEXT
HIBERNATE_TEXT
TRAMP_TEXT
*(.fixup)
*(.gnu.warning)
. = ALIGN(16);
*(.got) /* Global offset table */
}
. = ALIGN(SEGMENT_ALIGN);
_etext = .; /* End of text section */
RO_DATA(PAGE_SIZE) /* everything from this point to */
EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */
NOTES
. = ALIGN(SEGMENT_ALIGN);
__init_begin = .;
__inittext_begin = .;
INIT_TEXT_SECTION(8)
.exit.text : {
ARM_EXIT_KEEP(EXIT_TEXT)
}
. = ALIGN(4);
.altinstructions : {
__alt_instructions = .;
*(.altinstructions)
__alt_instructions_end = .;
}
.altinstr_replacement : {
*(.altinstr_replacement)
}
. = ALIGN(PAGE_SIZE);
__inittext_end = .;
__initdata_begin = .;
.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)
.rela : ALIGN(8) {
*(.rela .rela*)
}
__rela_offset = ABSOLUTE(ADDR(.rela) - KIMAGE_VADDR);
__rela_size = SIZEOF(.rela);
. = ALIGN(SEGMENT_ALIGN);
__initdata_end = .;
__init_end = .;
_data = .;
_sdata = .;
RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_ALIGN)
/*
* Data written with the MMU off but read with the MMU on requires
* cache lines to be invalidated, discarding up to a Cache Writeback
* Granule (CWG) of data from the cache. Keep the section that
* requires this type of maintenance to be in its own Cache Writeback
* Granule (CWG) area so the cache maintenance operations don't
* interfere with adjacent data.
*/
.mmuoff.data.write : ALIGN(SZ_2K) {
__mmuoff_data_start = .;
*(.mmuoff.data.write)
}
. = ALIGN(SZ_2K);
.mmuoff.data.read : {
*(.mmuoff.data.read)
__mmuoff_data_end = .;
}
PECOFF_EDATA_PADDING
__pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin);
_edata = .;
BSS_SECTION(0, 0, 0)
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
tramp_pg_dir = .;
. += PAGE_SIZE;
#endif
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
reserved_ttbr0 = .;
. += RESERVED_TTBR0_SIZE;
#endif
swapper_pg_dir = .;
. += SWAPPER_DIR_SIZE;
swapper_pg_end = .;
__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
_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")
#ifdef CONFIG_HIBERNATION
ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1))
<= SZ_4K, "Hibernate exit text too big or misaligned")
#endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE,
"Entry trampoline text too big")
#endif
/*
* If padding is applied before .head.text, virt<->phys conversions will fail.
*/
ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned")
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