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RETURN_ADDRESS is used at several places in glibc to mean a valid code address of the call site, but with pac-ret it may contain a pointer authentication code (PAC), so its definition is adjusted. This is gcc PR target/94891: __builtin_return_address should not expose signed pointers to user code where it can cause ABI issues. In glibc RETURN_ADDRESS is only changed if it is built with pac-ret. There is no detection for the specific gcc issue because it is hard to test and the additional xpac does not cause problems. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
219 lines
6.1 KiB
C
219 lines
6.1 KiB
C
/* Copyright (C) 1997-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _AARCH64_SYSDEP_H
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#define _AARCH64_SYSDEP_H
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#include <sysdeps/generic/sysdep.h>
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#ifdef __LP64__
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# define AARCH64_R(NAME) R_AARCH64_ ## NAME
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# define PTR_REG(n) x##n
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# define PTR_LOG_SIZE 3
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# define DELOUSE(n)
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#else
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# define AARCH64_R(NAME) R_AARCH64_P32_ ## NAME
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# define PTR_REG(n) w##n
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# define PTR_LOG_SIZE 2
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# define DELOUSE(n) mov w##n, w##n
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#endif
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#define PTR_SIZE (1<<PTR_LOG_SIZE)
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#ifndef __ASSEMBLER__
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/* Strip pointer authentication code from pointer p. */
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static inline void *
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strip_pac (void *p)
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{
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register void *ra asm ("x30") = (p);
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asm ("hint 7 // xpaclri" : "+r"(ra));
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return ra;
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}
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/* This is needed when glibc is built with -mbranch-protection=pac-ret
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with a gcc that is affected by PR target/94891. */
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# if HAVE_AARCH64_PAC_RET
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# undef RETURN_ADDRESS
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# define RETURN_ADDRESS(n) strip_pac (__builtin_return_address (n))
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# endif
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#endif
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#ifdef __ASSEMBLER__
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/* Syntactic details of assembler. */
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#define ASM_SIZE_DIRECTIVE(name) .size name,.-name
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/* Branch Target Identitication support. */
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#define BTI_C hint 34
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#define BTI_J hint 36
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/* Return address signing support (pac-ret). */
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#define PACIASP hint 25
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#define AUTIASP hint 29
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/* GNU_PROPERTY_AARCH64_* macros from elf.h for use in asm code. */
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#define FEATURE_1_AND 0xc0000000
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#define FEATURE_1_BTI 1
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#define FEATURE_1_PAC 2
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/* Add a NT_GNU_PROPERTY_TYPE_0 note. */
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#define GNU_PROPERTY(type, value) \
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.section .note.gnu.property, "a"; \
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.p2align 3; \
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.word 4; \
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.word 16; \
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.word 5; \
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.asciz "GNU"; \
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.word type; \
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.word 4; \
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.word value; \
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.word 0; \
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.text
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/* Add GNU property note with the supported features to all asm code
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where sysdep.h is included. */
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#if HAVE_AARCH64_BTI && HAVE_AARCH64_PAC_RET
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GNU_PROPERTY (FEATURE_1_AND, FEATURE_1_BTI|FEATURE_1_PAC)
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#elif HAVE_AARCH64_BTI
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GNU_PROPERTY (FEATURE_1_AND, FEATURE_1_BTI)
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#endif
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/* Define an entry point visible from C. */
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#define ENTRY(name) \
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.globl C_SYMBOL_NAME(name); \
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.type C_SYMBOL_NAME(name),%function; \
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.align 4; \
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C_LABEL(name) \
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cfi_startproc; \
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BTI_C; \
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CALL_MCOUNT
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/* Define an entry point visible from C. */
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#define ENTRY_ALIGN(name, align) \
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.globl C_SYMBOL_NAME(name); \
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.type C_SYMBOL_NAME(name),%function; \
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.p2align align; \
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C_LABEL(name) \
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cfi_startproc; \
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BTI_C; \
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CALL_MCOUNT
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/* Define an entry point visible from C with a specified alignment and
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pre-padding with NOPs. This can be used to ensure that a critical
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loop within a function is cache line aligned. Note this version
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does not adjust the padding if CALL_MCOUNT is defined. */
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#define ENTRY_ALIGN_AND_PAD(name, align, padding) \
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.globl C_SYMBOL_NAME(name); \
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.type C_SYMBOL_NAME(name),%function; \
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.p2align align; \
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.rep padding - 1; /* -1 for bti c. */ \
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nop; \
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.endr; \
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C_LABEL(name) \
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cfi_startproc; \
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BTI_C; \
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CALL_MCOUNT
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#undef END
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#define END(name) \
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cfi_endproc; \
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ASM_SIZE_DIRECTIVE(name)
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/* If compiled for profiling, call `mcount' at the start of each function. */
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#ifdef PROF
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# define CALL_MCOUNT \
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str x30, [sp, #-80]!; \
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cfi_adjust_cfa_offset (80); \
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cfi_rel_offset (x30, 0); \
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stp x0, x1, [sp, #16]; \
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cfi_rel_offset (x0, 16); \
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cfi_rel_offset (x1, 24); \
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stp x2, x3, [sp, #32]; \
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cfi_rel_offset (x2, 32); \
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cfi_rel_offset (x3, 40); \
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stp x4, x5, [sp, #48]; \
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cfi_rel_offset (x4, 48); \
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cfi_rel_offset (x5, 56); \
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stp x6, x7, [sp, #64]; \
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cfi_rel_offset (x6, 64); \
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cfi_rel_offset (x7, 72); \
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mov x0, x30; \
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bl mcount; \
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ldp x0, x1, [sp, #16]; \
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cfi_restore (x0); \
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cfi_restore (x1); \
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ldp x2, x3, [sp, #32]; \
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cfi_restore (x2); \
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cfi_restore (x3); \
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ldp x4, x5, [sp, #48]; \
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cfi_restore (x4); \
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cfi_restore (x5); \
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ldp x6, x7, [sp, #64]; \
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cfi_restore (x6); \
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cfi_restore (x7); \
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ldr x30, [sp], #80; \
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cfi_adjust_cfa_offset (-80); \
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cfi_restore (x30);
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#else
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# define CALL_MCOUNT /* Do nothing. */
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#endif
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/* Local label name for asm code. */
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#ifndef L
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# define L(name) .L##name
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#endif
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/* Load or store to/from a pc-relative EXPR into/from R, using T.
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Note R and T are register numbers and not register names. */
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#define LDST_PCREL(OP, R, T, EXPR) \
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adrp x##T, EXPR; \
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OP PTR_REG (R), [x##T, #:lo12:EXPR]; \
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/* Load or store to/from a got-relative EXPR into/from R, using T.
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Note R and T are register numbers and not register names. */
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#define LDST_GLOBAL(OP, R, T, EXPR) \
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adrp x##T, :got:EXPR; \
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ldr PTR_REG (T), [x##T, #:got_lo12:EXPR]; \
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OP PTR_REG (R), [x##T];
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/* Load an immediate into R.
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Note R is a register number and not a register name. */
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#ifdef __LP64__
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# define MOVL(R, NAME) \
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movz PTR_REG (R), #:abs_g3:NAME; \
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movk PTR_REG (R), #:abs_g2_nc:NAME; \
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movk PTR_REG (R), #:abs_g1_nc:NAME; \
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movk PTR_REG (R), #:abs_g0_nc:NAME;
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#else
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# define MOVL(R, NAME) \
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movz PTR_REG (R), #:abs_g1:NAME; \
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movk PTR_REG (R), #:abs_g0_nc:NAME;
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#endif
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/* Since C identifiers are not normally prefixed with an underscore
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on this system, the asm identifier `syscall_error' intrudes on the
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C name space. Make sure we use an innocuous name. */
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#define syscall_error __syscall_error
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#define mcount _mcount
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#endif /* __ASSEMBLER__ */
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#endif /* _AARCH64_SYSDEP_H */
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