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glibc/sysdeps/unix/sysv/linux/x86_64/sysdep.h
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/* Copyright (C) 2001,02 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#ifndef _LINUX_X86_64_SYSDEP_H | |
#define _LINUX_X86_64_SYSDEP_H 1 | |
/* There is some commonality. */ | |
#include <sysdeps/unix/x86_64/sysdep.h> | |
#include <bp-sym.h> | |
#include <bp-asm.h> | |
/* For Linux we can use the system call table in the header file | |
/usr/include/asm/unistd.h | |
of the kernel. But these symbols do not follow the SYS_* syntax | |
so we have to redefine the `SYS_ify' macro here. */ | |
#undef SYS_ify | |
#define SYS_ify(syscall_name) __NR_##syscall_name | |
/* This is a kludge to make syscalls.list find these under the names | |
pread and pwrite, since some kernel headers define those names | |
and some define the *64 names for the same system calls. */ | |
#if !defined __NR_pread && defined __NR_pread64 | |
# define __NR_pread __NR_pread64 | |
#endif | |
#if !defined __NR_pwrite && defined __NR_pwrite64 | |
# define __NR_pwrite __NR_pwrite64 | |
#endif | |
#ifdef __ASSEMBLER__ | |
/* Linux uses a negative return value to indicate syscall errors, | |
unlike most Unices, which use the condition codes' carry flag. | |
Since version 2.1 the return value of a system call might be | |
negative even if the call succeeded. E.g., the `lseek' system call | |
might return a large offset. Therefore we must not anymore test | |
for < 0, but test for a real error by making sure the value in %eax | |
is a real error number. Linus said he will make sure the no syscall | |
returns a value in -1 .. -4095 as a valid result so we can savely | |
test with -4095. */ | |
/* We don't want the label for the error handle to be global when we define | |
it here. */ | |
#ifdef PIC | |
# define SYSCALL_ERROR_LABEL 0f | |
#else | |
# define SYSCALL_ERROR_LABEL syscall_error | |
#endif | |
#undef PSEUDO | |
#define PSEUDO(name, syscall_name, args) \ | |
.text; \ | |
ENTRY (name) \ | |
DO_CALL (syscall_name, args); \ | |
cmpq $-4095, %rax; \ | |
jae SYSCALL_ERROR_LABEL; \ | |
L(pseudo_end): | |
#undef PSEUDO_END | |
#define PSEUDO_END(name) \ | |
SYSCALL_ERROR_HANDLER \ | |
END (name) | |
#ifndef PIC | |
#define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */ | |
#elif USE_TLS && HAVE___THREAD | |
# define SYSCALL_ERROR_HANDLER \ | |
movq errno@GOTTPOFF(%rip), %rcx; \ | |
xorq %rdx, %rdx; \ | |
subq %rax, %rdx; \ | |
movl %eax, %fs:0(%rcx) | |
#elif defined _LIBC_REENTRANT | |
/* Store (- %rax) into errno through the GOT. | |
Note that errno occupies only 4 bytes. */ | |
# define SYSCALL_ERROR_HANDLER \ | |
0: \ | |
xorq %rdx, %rdx; \ | |
subq %rax, %rdx; \ | |
pushq %rdx \ | |
PUSH_ERRNO_LOCATION_RETURN; \ | |
call BP_SYM (__errno_location)@PLT; \ | |
POP_ERRNO_LOCATION_RETURN; \ | |
popq %rdx; \ | |
movl %edx, (%rax); \ | |
orq $-1, %rax; \ | |
jmp L(pseudo_end); | |
/* A quick note: it is assumed that the call to `__errno_location' does | |
not modify the stack! */ | |
#else /* Not _LIBC_REENTRANT. */ | |
# define SYSCALL_ERROR_HANDLER \ | |
0:movq errno@GOTPCREL(%RIP), %rcx; \ | |
xorq %rdx, %rdx; \ | |
subq %rax, %rdx; \ | |
movl %edx, (%rcx); \ | |
orq $-1, %rax; \ | |
jmp L(pseudo_end); | |
#endif /* PIC */ | |
/* Linux/x86-64 takes system call arguments in registers: | |
Register setup: | |
system call number rax | |
arg 1 rdi | |
arg 2 rsi | |
arg 3 rdx | |
arg 4 rcx | |
arg 5 r8 | |
arg 6 r9 | |
return address from | |
syscall rcx | |
additionally clobered: r12-r15,rbx,rbp | |
eflags from syscall r11 | |
The compiler is going to form a call by coming here, through PSEUDO, with arguments: | |
syscall number in the DO_CALL macro | |
arg 1 rdi | |
arg 2 rsi | |
arg 3 rdx | |
arg 4 r10 | |
arg 5 r8 | |
arg 6 r9 | |
We have to take care that the stack is alignedto 16 bytes. When | |
called the stack is not aligned since the return address has just | |
been pushed. | |
Syscalls of more than 6 arguments are not supported. */ | |
#undef DO_CALL | |
#define DO_CALL(syscall_name, args) \ | |
DOARGS_##args \ | |
movq $SYS_ify (syscall_name), %rax; \ | |
syscall; | |
#define DOARGS_0 /* nothing */ | |
#define DOARGS_1 /* nothing */ | |
#define DOARGS_2 /* nothing */ | |
#define DOARGS_3 /* nothing */ | |
#define DOARGS_4 movq %rcx, %r10; | |
#define DOARGS_5 DOARGS_4 | |
#define DOARGS_6 DOARGS_5 | |
#else /* !__ASSEMBLER__ */ | |
/* Define a macro which expands inline into the wrapper code for a system | |
call. */ | |
#undef INLINE_SYSCALL | |
#define INLINE_SYSCALL(name, nr, args...) \ | |
({ \ | |
unsigned long resultvar; \ | |
LOAD_ARGS_##nr (args) \ | |
asm volatile ( \ | |
"movq %1, %%rax\n\t" \ | |
"syscall\n\t" \ | |
: "=a" (resultvar) \ | |
: "i" (__NR_##name) ASM_ARGS_##nr : "memory", "cc", "r11", "cx"); \ | |
if (resultvar >= (unsigned long) -4095) \ | |
{ \ | |
__set_errno (-resultvar); \ | |
resultvar = (unsigned long) -1; \ | |
} \ | |
(long) resultvar; }) | |
#define LOAD_ARGS_0() | |
#define ASM_ARGS_0 | |
#define LOAD_ARGS_1(a1) \ | |
register long int _a1 asm ("rdi") = (long) (a1); \ | |
LOAD_ARGS_0 () | |
#define ASM_ARGS_1 ASM_ARGS_0, "r" (_a1) | |
#define LOAD_ARGS_2(a1, a2) \ | |
register long int _a2 asm ("rsi") = (long) (a2); \ | |
LOAD_ARGS_1 (a1) | |
#define ASM_ARGS_2 ASM_ARGS_1, "r" (_a2) | |
#define LOAD_ARGS_3(a1, a2, a3) \ | |
register long int _a3 asm ("rdx") = (long) (a3); \ | |
LOAD_ARGS_2 (a1, a2) | |
#define ASM_ARGS_3 ASM_ARGS_2, "r" (_a3) | |
#define LOAD_ARGS_4(a1, a2, a3, a4) \ | |
register long int _a4 asm ("r10") = (long) (a4); \ | |
LOAD_ARGS_3 (a1, a2, a3) | |
#define ASM_ARGS_4 ASM_ARGS_3, "r" (_a4) | |
#define LOAD_ARGS_5(a1, a2, a3, a4, a5) \ | |
register long int _a5 asm ("r8") = (long) (a5); \ | |
LOAD_ARGS_4 (a1, a2, a3, a4) | |
#define ASM_ARGS_5 ASM_ARGS_4, "r" (_a5) | |
#define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6) \ | |
register long int _a6 asm ("r9") = (long) (a6); \ | |
LOAD_ARGS_5 (a1, a2, a3, a4, a5) | |
#define ASM_ARGS_6 ASM_ARGS_5, "r" (_a6) | |
#endif /* __ASSEMBLER__ */ | |
#endif /* linux/x86_64/sysdep.h */ |