forked from Minki/linux
2dd0e8d2d2
Add support for basic kernel probes(kprobes) and jump probes (jprobes) for ARM64. Kprobes utilizes software breakpoint and single step debug exceptions supported on ARM v8. A software breakpoint is placed at the probe address to trap the kernel execution into the kprobe handler. ARM v8 supports enabling single stepping before the break exception return (ERET), with next PC in exception return address (ELR_EL1). The kprobe handler prepares an executable memory slot for out-of-line execution with a copy of the original instruction being probed, and enables single stepping. The PC is set to the out-of-line slot address before the ERET. With this scheme, the instruction is executed with the exact same register context except for the PC (and DAIF) registers. Debug mask (PSTATE.D) is enabled only when single stepping a recursive kprobe, e.g.: during kprobes reenter so that probed instruction can be single stepped within the kprobe handler -exception- context. The recursion depth of kprobe is always 2, i.e. upon probe re-entry, any further re-entry is prevented by not calling handlers and the case counted as a missed kprobe). Single stepping from the x-o-l slot has a drawback for PC-relative accesses like branching and symbolic literals access as the offset from the new PC (slot address) may not be ensured to fit in the immediate value of the opcode. Such instructions need simulation, so reject probing them. Instructions generating exceptions or cpu mode change are rejected for probing. Exclusive load/store instructions are rejected too. Additionally, the code is checked to see if it is inside an exclusive load/store sequence (code from Pratyush). System instructions are mostly enabled for stepping, except MSR/MRS accesses to "DAIF" flags in PSTATE, which are not safe for probing. This also changes arch/arm64/include/asm/ptrace.h to use include/asm-generic/ptrace.h. Thanks to Steve Capper and Pratyush Anand for several suggested Changes. Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Signed-off-by: David A. Long <dave.long@linaro.org> Signed-off-by: Pratyush Anand <panand@redhat.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
230 lines
5.2 KiB
ArmAsm
230 lines
5.2 KiB
ArmAsm
/*
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* ld script to make ARM Linux kernel
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* taken from the i386 version by Russell King
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* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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*/
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#include <asm-generic/vmlinux.lds.h>
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#include <asm/cache.h>
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#include <asm/kernel-pgtable.h>
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#include <asm/thread_info.h>
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#include <asm/memory.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include "image.h"
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/* .exit.text needed in case of alternative patching */
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#define ARM_EXIT_KEEP(x) x
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#define ARM_EXIT_DISCARD(x)
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OUTPUT_ARCH(aarch64)
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ENTRY(_text)
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jiffies = jiffies_64;
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#define HYPERVISOR_TEXT \
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/* \
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* Align to 4 KB so that \
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* a) the HYP vector table is at its minimum \
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* alignment of 2048 bytes \
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* b) the HYP init code will not cross a page \
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* boundary if its size does not exceed \
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* 4 KB (see related ASSERT() below) \
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*/ \
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. = ALIGN(SZ_4K); \
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VMLINUX_SYMBOL(__hyp_idmap_text_start) = .; \
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*(.hyp.idmap.text) \
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VMLINUX_SYMBOL(__hyp_idmap_text_end) = .; \
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VMLINUX_SYMBOL(__hyp_text_start) = .; \
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*(.hyp.text) \
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VMLINUX_SYMBOL(__hyp_text_end) = .;
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#define IDMAP_TEXT \
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. = ALIGN(SZ_4K); \
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VMLINUX_SYMBOL(__idmap_text_start) = .; \
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*(.idmap.text) \
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VMLINUX_SYMBOL(__idmap_text_end) = .;
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#ifdef CONFIG_HIBERNATION
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#define HIBERNATE_TEXT \
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. = ALIGN(SZ_4K); \
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VMLINUX_SYMBOL(__hibernate_exit_text_start) = .;\
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*(.hibernate_exit.text) \
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VMLINUX_SYMBOL(__hibernate_exit_text_end) = .;
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#else
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#define HIBERNATE_TEXT
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#endif
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/*
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* The size of the PE/COFF section that covers the kernel image, which
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* runs from stext to _edata, must be a round multiple of the PE/COFF
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* FileAlignment, which we set to its minimum value of 0x200. 'stext'
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* itself is 4 KB aligned, so padding out _edata to a 0x200 aligned
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* boundary should be sufficient.
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*/
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PECOFF_FILE_ALIGNMENT = 0x200;
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#ifdef CONFIG_EFI
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#define PECOFF_EDATA_PADDING \
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.pecoff_edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGNMENT); }
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#else
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#define PECOFF_EDATA_PADDING
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#endif
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#if defined(CONFIG_DEBUG_ALIGN_RODATA)
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/*
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* 4 KB granule: 1 level 2 entry
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* 16 KB granule: 128 level 3 entries, with contiguous bit
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* 64 KB granule: 32 level 3 entries, with contiguous bit
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*/
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#define SEGMENT_ALIGN SZ_2M
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#else
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/*
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* 4 KB granule: 16 level 3 entries, with contiguous bit
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* 16 KB granule: 4 level 3 entries, without contiguous bit
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* 64 KB granule: 1 level 3 entry
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*/
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#define SEGMENT_ALIGN SZ_64K
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#endif
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SECTIONS
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{
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/*
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* XXX: The linker does not define how output sections are
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* assigned to input sections when there are multiple statements
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* matching the same input section name. There is no documented
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* order of matching.
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*/
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/DISCARD/ : {
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ARM_EXIT_DISCARD(EXIT_TEXT)
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ARM_EXIT_DISCARD(EXIT_DATA)
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EXIT_CALL
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*(.discard)
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*(.discard.*)
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*(.interp .dynamic)
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}
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. = KIMAGE_VADDR + TEXT_OFFSET;
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.head.text : {
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_text = .;
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HEAD_TEXT
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}
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.text : { /* Real text segment */
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_stext = .; /* Text and read-only data */
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__exception_text_start = .;
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*(.exception.text)
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__exception_text_end = .;
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IRQENTRY_TEXT
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SOFTIRQENTRY_TEXT
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TEXT_TEXT
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SCHED_TEXT
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LOCK_TEXT
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KPROBES_TEXT
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HYPERVISOR_TEXT
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IDMAP_TEXT
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HIBERNATE_TEXT
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*(.fixup)
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*(.gnu.warning)
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. = ALIGN(16);
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*(.got) /* Global offset table */
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}
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. = ALIGN(SEGMENT_ALIGN);
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RO_DATA(PAGE_SIZE) /* everything from this point to */
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EXCEPTION_TABLE(8) /* _etext will be marked RO NX */
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NOTES
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. = ALIGN(SEGMENT_ALIGN);
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_etext = .; /* End of text and rodata section */
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__init_begin = .;
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INIT_TEXT_SECTION(8)
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.exit.text : {
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ARM_EXIT_KEEP(EXIT_TEXT)
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}
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.init.data : {
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INIT_DATA
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INIT_SETUP(16)
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INIT_CALLS
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CON_INITCALL
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SECURITY_INITCALL
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INIT_RAM_FS
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*(.init.rodata.* .init.bss) /* from the EFI stub */
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}
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.exit.data : {
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ARM_EXIT_KEEP(EXIT_DATA)
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}
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PERCPU_SECTION(L1_CACHE_BYTES)
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. = ALIGN(4);
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.altinstructions : {
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__alt_instructions = .;
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*(.altinstructions)
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__alt_instructions_end = .;
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}
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.altinstr_replacement : {
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*(.altinstr_replacement)
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}
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.rela : ALIGN(8) {
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*(.rela .rela*)
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}
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.dynsym : ALIGN(8) {
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*(.dynsym)
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}
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.dynstr : {
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*(.dynstr)
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}
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.hash : {
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*(.hash)
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}
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__rela_offset = ADDR(.rela) - KIMAGE_VADDR;
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__rela_size = SIZEOF(.rela);
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__dynsym_offset = ADDR(.dynsym) - KIMAGE_VADDR;
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. = ALIGN(SEGMENT_ALIGN);
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__init_end = .;
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_data = .;
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_sdata = .;
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RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
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PECOFF_EDATA_PADDING
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_edata = .;
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BSS_SECTION(0, 0, 0)
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. = ALIGN(PAGE_SIZE);
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idmap_pg_dir = .;
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. += IDMAP_DIR_SIZE;
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swapper_pg_dir = .;
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. += SWAPPER_DIR_SIZE;
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_end = .;
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STABS_DEBUG
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HEAD_SYMBOLS
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}
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/*
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* The HYP init code and ID map text can't be longer than a page each,
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* and should not cross a page boundary.
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*/
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ASSERT(__hyp_idmap_text_end - (__hyp_idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
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"HYP init code too big or misaligned")
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ASSERT(__idmap_text_end - (__idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
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"ID map text too big or misaligned")
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#ifdef CONFIG_HIBERNATION
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ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1))
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<= SZ_4K, "Hibernate exit text too big or misaligned")
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#endif
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/*
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* If padding is applied before .head.text, virt<->phys conversions will fail.
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*/
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ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned")
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