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/* Copyright (C) 2001,02,03 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>
#include <tls.h>
#ifdef IS_IN_rtld
# include <dl-sysdep.h> /* Defines RTLD_PRIVATE_ERRNO. */
#endif
/* 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 RTLD_PRIVATE_ERRNO
# define SYSCALL_ERROR_HANDLER \
0: \
leaq errno(%rip), %rcx; \
xorq %rdx, %rdx; \
subq %rax, %rdx; \
movl %edx, (%rcx); \
orq $-1, %rax; \
jmp L(pseudo_end);
#elif USE___THREAD
# ifndef NOT_IN_libc
# define SYSCALL_ERROR_ERRNO __libc_errno
# else
# define SYSCALL_ERROR_ERRNO errno
# endif
# define SYSCALL_ERROR_HANDLER \
0: \
movq SYSCALL_ERROR_ERRNO@GOTTPOFF(%rip), %rcx;\
xorq %rdx, %rdx; \
subq %rax, %rdx; \
movl %edx, %fs:(%rcx); \
orq $-1, %rax; \
jmp L(pseudo_end);
#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 = INTERNAL_SYSCALL (name, , nr, args); \
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (resultvar, ), 0)) \
{ \
__set_errno (INTERNAL_SYSCALL_ERRNO (resultvar, )); \
resultvar = (unsigned long) -1; \
} \
(long) resultvar; })
#undef INTERNAL_SYSCALL_DECL
#define INTERNAL_SYSCALL_DECL(err) do { } while (0)
#undef INTERNAL_SYSCALL
#define INTERNAL_SYSCALL(name, err, 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"); \
(long) resultvar; })
#undef INTERNAL_SYSCALL_ERROR_P
#define INTERNAL_SYSCALL_ERROR_P(val, err) \
((unsigned long) (val) >= -4095L)
#undef INTERNAL_SYSCALL_ERRNO
#define INTERNAL_SYSCALL_ERRNO(val, err) (-(val))
#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 */
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