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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Peter Zijlstra](/assets/img/avatar_default.png)
Generic function-alignment infrastructure. Architectures can select FUNCTION_ALIGNMENT_xxB symbols; the FUNCTION_ALIGNMENT symbol is then set to the largest such selected size, 0 otherwise. From this the -falign-functions compiler argument and __ALIGN macro are set. This incorporates the DEBUG_FORCE_FUNCTION_ALIGN_64B knob and future alignment requirements for x86_64 (later in this series) into a single place. NOTE: also removes the 0x90 filler byte from the generic __ALIGN primitive, that value makes no sense outside of x86. NOTE: .balign 0 reverts to a no-op. Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220915111143.719248727@infradead.org
360 lines
9.6 KiB
C
360 lines
9.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_LINKAGE_H
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#define _LINUX_LINKAGE_H
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#include <linux/compiler_types.h>
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#include <linux/stringify.h>
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#include <linux/export.h>
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#include <asm/linkage.h>
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/* Some toolchains use other characters (e.g. '`') to mark new line in macro */
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#ifndef ASM_NL
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#define ASM_NL ;
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#endif
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#ifdef __cplusplus
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#define CPP_ASMLINKAGE extern "C"
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#else
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#define CPP_ASMLINKAGE
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#endif
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#ifndef asmlinkage
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#define asmlinkage CPP_ASMLINKAGE
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#endif
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#ifndef cond_syscall
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#define cond_syscall(x) asm( \
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".weak " __stringify(x) "\n\t" \
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".set " __stringify(x) "," \
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__stringify(sys_ni_syscall))
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#endif
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#ifndef SYSCALL_ALIAS
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#define SYSCALL_ALIAS(alias, name) asm( \
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".globl " __stringify(alias) "\n\t" \
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".set " __stringify(alias) "," \
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__stringify(name))
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#endif
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#define __page_aligned_data __section(".data..page_aligned") __aligned(PAGE_SIZE)
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#define __page_aligned_bss __section(".bss..page_aligned") __aligned(PAGE_SIZE)
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/*
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* For assembly routines.
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*
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* Note when using these that you must specify the appropriate
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* alignment directives yourself
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*/
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#define __PAGE_ALIGNED_DATA .section ".data..page_aligned", "aw"
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#define __PAGE_ALIGNED_BSS .section ".bss..page_aligned", "aw"
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/*
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* This is used by architectures to keep arguments on the stack
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* untouched by the compiler by keeping them live until the end.
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* The argument stack may be owned by the assembly-language
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* caller, not the callee, and gcc doesn't always understand
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* that.
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*
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* We have the return value, and a maximum of six arguments.
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*
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* This should always be followed by a "return ret" for the
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* protection to work (ie no more work that the compiler might
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* end up needing stack temporaries for).
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*/
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/* Assembly files may be compiled with -traditional .. */
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#ifndef __ASSEMBLY__
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#ifndef asmlinkage_protect
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# define asmlinkage_protect(n, ret, args...) do { } while (0)
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#endif
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#endif
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#ifndef __ALIGN
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#define __ALIGN .balign CONFIG_FUNCTION_ALIGNMENT
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#define __ALIGN_STR __stringify(__ALIGN)
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#endif
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#ifdef __ASSEMBLY__
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/* SYM_T_FUNC -- type used by assembler to mark functions */
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#ifndef SYM_T_FUNC
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#define SYM_T_FUNC STT_FUNC
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#endif
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/* SYM_T_OBJECT -- type used by assembler to mark data */
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#ifndef SYM_T_OBJECT
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#define SYM_T_OBJECT STT_OBJECT
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#endif
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/* SYM_T_NONE -- type used by assembler to mark entries of unknown type */
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#ifndef SYM_T_NONE
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#define SYM_T_NONE STT_NOTYPE
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#endif
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/* SYM_A_* -- align the symbol? */
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#define SYM_A_ALIGN ALIGN
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#define SYM_A_NONE /* nothing */
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/* SYM_L_* -- linkage of symbols */
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#define SYM_L_GLOBAL(name) .globl name
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#define SYM_L_WEAK(name) .weak name
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#define SYM_L_LOCAL(name) /* nothing */
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#ifndef LINKER_SCRIPT
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#define ALIGN __ALIGN
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#define ALIGN_STR __ALIGN_STR
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/* === DEPRECATED annotations === */
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#ifndef CONFIG_ARCH_USE_SYM_ANNOTATIONS
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#ifndef GLOBAL
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/* deprecated, use SYM_DATA*, SYM_ENTRY, or similar */
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#define GLOBAL(name) \
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.globl name ASM_NL \
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name:
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#endif
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#ifndef ENTRY
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/* deprecated, use SYM_FUNC_START */
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#define ENTRY(name) \
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SYM_FUNC_START(name)
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#endif
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#endif /* CONFIG_ARCH_USE_SYM_ANNOTATIONS */
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#endif /* LINKER_SCRIPT */
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#ifndef CONFIG_ARCH_USE_SYM_ANNOTATIONS
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#ifndef WEAK
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/* deprecated, use SYM_FUNC_START_WEAK* */
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#define WEAK(name) \
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SYM_FUNC_START_WEAK(name)
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#endif
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#ifndef END
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/* deprecated, use SYM_FUNC_END, SYM_DATA_END, or SYM_END */
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#define END(name) \
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.size name, .-name
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#endif
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/* If symbol 'name' is treated as a subroutine (gets called, and returns)
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* then please use ENDPROC to mark 'name' as STT_FUNC for the benefit of
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* static analysis tools such as stack depth analyzer.
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*/
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#ifndef ENDPROC
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/* deprecated, use SYM_FUNC_END */
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#define ENDPROC(name) \
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SYM_FUNC_END(name)
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#endif
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#endif /* CONFIG_ARCH_USE_SYM_ANNOTATIONS */
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/* === generic annotations === */
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/* SYM_ENTRY -- use only if you have to for non-paired symbols */
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#ifndef SYM_ENTRY
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#define SYM_ENTRY(name, linkage, align...) \
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linkage(name) ASM_NL \
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align ASM_NL \
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name:
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#endif
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/* SYM_START -- use only if you have to */
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#ifndef SYM_START
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#define SYM_START(name, linkage, align...) \
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SYM_ENTRY(name, linkage, align)
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#endif
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/* SYM_END -- use only if you have to */
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#ifndef SYM_END
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#define SYM_END(name, sym_type) \
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.type name sym_type ASM_NL \
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.set .L__sym_size_##name, .-name ASM_NL \
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.size name, .L__sym_size_##name
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#endif
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/* SYM_ALIAS -- use only if you have to */
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#ifndef SYM_ALIAS
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#define SYM_ALIAS(alias, name, linkage) \
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linkage(alias) ASM_NL \
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.set alias, name ASM_NL
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#endif
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/* === code annotations === */
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/*
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* FUNC -- C-like functions (proper stack frame etc.)
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* CODE -- non-C code (e.g. irq handlers with different, special stack etc.)
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*
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* Objtool validates stack for FUNC, but not for CODE.
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* Objtool generates debug info for both FUNC & CODE, but needs special
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* annotations for each CODE's start (to describe the actual stack frame).
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*
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* Objtool requires that all code must be contained in an ELF symbol. Symbol
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* names that have a .L prefix do not emit symbol table entries. .L
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* prefixed symbols can be used within a code region, but should be avoided for
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* denoting a range of code via ``SYM_*_START/END`` annotations.
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*
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* ALIAS -- does not generate debug info -- the aliased function will
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*/
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/* SYM_INNER_LABEL_ALIGN -- only for labels in the middle of code */
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#ifndef SYM_INNER_LABEL_ALIGN
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#define SYM_INNER_LABEL_ALIGN(name, linkage) \
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.type name SYM_T_NONE ASM_NL \
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SYM_ENTRY(name, linkage, SYM_A_ALIGN)
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#endif
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/* SYM_INNER_LABEL -- only for labels in the middle of code */
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#ifndef SYM_INNER_LABEL
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#define SYM_INNER_LABEL(name, linkage) \
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.type name SYM_T_NONE ASM_NL \
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SYM_ENTRY(name, linkage, SYM_A_NONE)
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#endif
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/* SYM_FUNC_START -- use for global functions */
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#ifndef SYM_FUNC_START
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#define SYM_FUNC_START(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)
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#endif
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/* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
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#ifndef SYM_FUNC_START_NOALIGN
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#define SYM_FUNC_START_NOALIGN(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
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#endif
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/* SYM_FUNC_START_LOCAL -- use for local functions */
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#ifndef SYM_FUNC_START_LOCAL
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#define SYM_FUNC_START_LOCAL(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN)
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#endif
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/* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
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#ifndef SYM_FUNC_START_LOCAL_NOALIGN
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#define SYM_FUNC_START_LOCAL_NOALIGN(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
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#endif
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/* SYM_FUNC_START_WEAK -- use for weak functions */
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#ifndef SYM_FUNC_START_WEAK
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#define SYM_FUNC_START_WEAK(name) \
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SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN)
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#endif
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/* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */
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#ifndef SYM_FUNC_START_WEAK_NOALIGN
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#define SYM_FUNC_START_WEAK_NOALIGN(name) \
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SYM_START(name, SYM_L_WEAK, SYM_A_NONE)
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#endif
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/*
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* SYM_FUNC_END -- the end of SYM_FUNC_START_LOCAL, SYM_FUNC_START,
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* SYM_FUNC_START_WEAK, ...
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*/
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#ifndef SYM_FUNC_END
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#define SYM_FUNC_END(name) \
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SYM_END(name, SYM_T_FUNC)
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#endif
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/*
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* SYM_FUNC_ALIAS -- define a global alias for an existing function
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*/
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#ifndef SYM_FUNC_ALIAS
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#define SYM_FUNC_ALIAS(alias, name) \
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SYM_ALIAS(alias, name, SYM_L_GLOBAL)
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#endif
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/*
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* SYM_FUNC_ALIAS_LOCAL -- define a local alias for an existing function
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*/
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#ifndef SYM_FUNC_ALIAS_LOCAL
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#define SYM_FUNC_ALIAS_LOCAL(alias, name) \
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SYM_ALIAS(alias, name, SYM_L_LOCAL)
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#endif
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/*
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* SYM_FUNC_ALIAS_WEAK -- define a weak global alias for an existing function
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*/
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#ifndef SYM_FUNC_ALIAS_WEAK
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#define SYM_FUNC_ALIAS_WEAK(alias, name) \
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SYM_ALIAS(alias, name, SYM_L_WEAK)
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#endif
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/* SYM_CODE_START -- use for non-C (special) functions */
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#ifndef SYM_CODE_START
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#define SYM_CODE_START(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)
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#endif
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/* SYM_CODE_START_NOALIGN -- use for non-C (special) functions, w/o alignment */
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#ifndef SYM_CODE_START_NOALIGN
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#define SYM_CODE_START_NOALIGN(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
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#endif
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/* SYM_CODE_START_LOCAL -- use for local non-C (special) functions */
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#ifndef SYM_CODE_START_LOCAL
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#define SYM_CODE_START_LOCAL(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN)
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#endif
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/*
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* SYM_CODE_START_LOCAL_NOALIGN -- use for local non-C (special) functions,
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* w/o alignment
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*/
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#ifndef SYM_CODE_START_LOCAL_NOALIGN
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#define SYM_CODE_START_LOCAL_NOALIGN(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
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#endif
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/* SYM_CODE_END -- the end of SYM_CODE_START_LOCAL, SYM_CODE_START, ... */
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#ifndef SYM_CODE_END
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#define SYM_CODE_END(name) \
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SYM_END(name, SYM_T_NONE)
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#endif
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/* === data annotations === */
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/* SYM_DATA_START -- global data symbol */
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#ifndef SYM_DATA_START
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#define SYM_DATA_START(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
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#endif
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/* SYM_DATA_START -- local data symbol */
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#ifndef SYM_DATA_START_LOCAL
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#define SYM_DATA_START_LOCAL(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
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#endif
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/* SYM_DATA_END -- the end of SYM_DATA_START symbol */
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#ifndef SYM_DATA_END
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#define SYM_DATA_END(name) \
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SYM_END(name, SYM_T_OBJECT)
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#endif
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/* SYM_DATA_END_LABEL -- the labeled end of SYM_DATA_START symbol */
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#ifndef SYM_DATA_END_LABEL
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#define SYM_DATA_END_LABEL(name, linkage, label) \
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linkage(label) ASM_NL \
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.type label SYM_T_OBJECT ASM_NL \
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label: \
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SYM_END(name, SYM_T_OBJECT)
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#endif
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/* SYM_DATA -- start+end wrapper around simple global data */
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#ifndef SYM_DATA
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#define SYM_DATA(name, data...) \
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SYM_DATA_START(name) ASM_NL \
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data ASM_NL \
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SYM_DATA_END(name)
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#endif
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/* SYM_DATA_LOCAL -- start+end wrapper around simple local data */
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#ifndef SYM_DATA_LOCAL
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#define SYM_DATA_LOCAL(name, data...) \
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SYM_DATA_START_LOCAL(name) ASM_NL \
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data ASM_NL \
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SYM_DATA_END(name)
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#endif
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#endif /* __ASSEMBLY__ */
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#endif /* _LINUX_LINKAGE_H */
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