227 lines
6.8 KiB
C
227 lines
6.8 KiB
C
/* Copyright (C) 2001,02 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
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License as published by the Free Software Foundation; either
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version 2.1 of the 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#ifndef _LINUX_X86_64_SYSDEP_H
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#define _LINUX_X86_64_SYSDEP_H 1
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/* There is some commonality. */
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#include <sysdeps/unix/x86_64/sysdep.h>
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#include <bp-sym.h>
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#include <bp-asm.h>
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#ifdef IS_IN_rtld
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# include <dl-sysdep.h> /* Defines RTLD_PRIVATE_ERRNO. */
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#endif
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/* For Linux we can use the system call table in the header file
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/usr/include/asm/unistd.h
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of the kernel. But these symbols do not follow the SYS_* syntax
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so we have to redefine the `SYS_ify' macro here. */
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#undef SYS_ify
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#define SYS_ify(syscall_name) __NR_##syscall_name
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/* This is a kludge to make syscalls.list find these under the names
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pread and pwrite, since some kernel headers define those names
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and some define the *64 names for the same system calls. */
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#if !defined __NR_pread && defined __NR_pread64
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# define __NR_pread __NR_pread64
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#endif
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#if !defined __NR_pwrite && defined __NR_pwrite64
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# define __NR_pwrite __NR_pwrite64
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#endif
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#ifdef __ASSEMBLER__
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/* Linux uses a negative return value to indicate syscall errors,
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unlike most Unices, which use the condition codes' carry flag.
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Since version 2.1 the return value of a system call might be
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negative even if the call succeeded. E.g., the `lseek' system call
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might return a large offset. Therefore we must not anymore test
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for < 0, but test for a real error by making sure the value in %eax
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is a real error number. Linus said he will make sure the no syscall
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returns a value in -1 .. -4095 as a valid result so we can savely
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test with -4095. */
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/* We don't want the label for the error handle to be global when we define
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it here. */
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#ifdef PIC
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# define SYSCALL_ERROR_LABEL 0f
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#else
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# define SYSCALL_ERROR_LABEL syscall_error
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#endif
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#undef PSEUDO
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#define PSEUDO(name, syscall_name, args) \
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.text; \
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ENTRY (name) \
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DO_CALL (syscall_name, args); \
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cmpq $-4095, %rax; \
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jae SYSCALL_ERROR_LABEL; \
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L(pseudo_end):
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#undef PSEUDO_END
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#define PSEUDO_END(name) \
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SYSCALL_ERROR_HANDLER \
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END (name)
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#ifndef PIC
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#define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
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#elif USE___THREAD
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# define SYSCALL_ERROR_HANDLER \
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movq errno@GOTTPOFF(%rip), %rcx; \
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xorq %rdx, %rdx; \
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subq %rax, %rdx; \
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movl %eax, %fs:0(%rcx)
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#elif RTLD_PRIVATE_ERRNO
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# define SYSCALL_ERROR_HANDLER \
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leaq errno(%rip), %rcx; \
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xorq %rdx, %rdx; \
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subq %rax, %rdx; \
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movl %eax, (%rcx)
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#elif defined _LIBC_REENTRANT
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/* Store (- %rax) into errno through the GOT.
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Note that errno occupies only 4 bytes. */
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# define SYSCALL_ERROR_HANDLER \
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0: \
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xorq %rdx, %rdx; \
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subq %rax, %rdx; \
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pushq %rdx \
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PUSH_ERRNO_LOCATION_RETURN; \
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call BP_SYM (__errno_location)@PLT; \
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POP_ERRNO_LOCATION_RETURN; \
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popq %rdx; \
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movl %edx, (%rax); \
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orq $-1, %rax; \
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jmp L(pseudo_end);
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/* A quick note: it is assumed that the call to `__errno_location' does
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not modify the stack! */
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#else /* Not _LIBC_REENTRANT. */
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# define SYSCALL_ERROR_HANDLER \
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0:movq errno@GOTPCREL(%RIP), %rcx; \
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xorq %rdx, %rdx; \
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subq %rax, %rdx; \
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movl %edx, (%rcx); \
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orq $-1, %rax; \
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jmp L(pseudo_end);
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#endif /* PIC */
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/* Linux/x86-64 takes system call arguments in registers:
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Register setup:
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system call number rax
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arg 1 rdi
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arg 2 rsi
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arg 3 rdx
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arg 4 rcx
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arg 5 r8
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arg 6 r9
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return address from
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syscall rcx
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additionally clobered: r12-r15,rbx,rbp
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eflags from syscall r11
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The compiler is going to form a call by coming here, through PSEUDO, with arguments:
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syscall number in the DO_CALL macro
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arg 1 rdi
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arg 2 rsi
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arg 3 rdx
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arg 4 r10
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arg 5 r8
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arg 6 r9
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We have to take care that the stack is alignedto 16 bytes. When
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called the stack is not aligned since the return address has just
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been pushed.
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Syscalls of more than 6 arguments are not supported. */
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#undef DO_CALL
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#define DO_CALL(syscall_name, args) \
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DOARGS_##args \
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movq $SYS_ify (syscall_name), %rax; \
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syscall;
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#define DOARGS_0 /* nothing */
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#define DOARGS_1 /* nothing */
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#define DOARGS_2 /* nothing */
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#define DOARGS_3 /* nothing */
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#define DOARGS_4 movq %rcx, %r10;
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#define DOARGS_5 DOARGS_4
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#define DOARGS_6 DOARGS_5
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#else /* !__ASSEMBLER__ */
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/* Define a macro which expands inline into the wrapper code for a system
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call. */
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#undef INLINE_SYSCALL
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#define INLINE_SYSCALL(name, nr, args...) \
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({ \
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unsigned long resultvar; \
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LOAD_ARGS_##nr (args) \
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asm volatile ( \
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"movq %1, %%rax\n\t" \
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"syscall\n\t" \
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: "=a" (resultvar) \
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: "i" (__NR_##name) ASM_ARGS_##nr : "memory", "cc", "r11", "cx"); \
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if (resultvar >= (unsigned long) -4095) \
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{ \
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__set_errno (-resultvar); \
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resultvar = (unsigned long) -1; \
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} \
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(long) resultvar; })
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#define LOAD_ARGS_0()
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#define ASM_ARGS_0
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#define LOAD_ARGS_1(a1) \
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register long int _a1 asm ("rdi") = (long) (a1); \
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LOAD_ARGS_0 ()
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#define ASM_ARGS_1 ASM_ARGS_0, "r" (_a1)
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#define LOAD_ARGS_2(a1, a2) \
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register long int _a2 asm ("rsi") = (long) (a2); \
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LOAD_ARGS_1 (a1)
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#define ASM_ARGS_2 ASM_ARGS_1, "r" (_a2)
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#define LOAD_ARGS_3(a1, a2, a3) \
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register long int _a3 asm ("rdx") = (long) (a3); \
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LOAD_ARGS_2 (a1, a2)
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#define ASM_ARGS_3 ASM_ARGS_2, "r" (_a3)
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#define LOAD_ARGS_4(a1, a2, a3, a4) \
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register long int _a4 asm ("r10") = (long) (a4); \
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LOAD_ARGS_3 (a1, a2, a3)
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#define ASM_ARGS_4 ASM_ARGS_3, "r" (_a4)
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#define LOAD_ARGS_5(a1, a2, a3, a4, a5) \
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register long int _a5 asm ("r8") = (long) (a5); \
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LOAD_ARGS_4 (a1, a2, a3, a4)
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#define ASM_ARGS_5 ASM_ARGS_4, "r" (_a5)
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#define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6) \
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register long int _a6 asm ("r9") = (long) (a6); \
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LOAD_ARGS_5 (a1, a2, a3, a4, a5)
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#define ASM_ARGS_6 ASM_ARGS_5, "r" (_a6)
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#endif /* __ASSEMBLER__ */
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#endif /* linux/x86_64/sysdep.h */
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