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Diffstat (limited to 'libc/sysdeps/linux/x86_64/sysdep.h')
| -rw-r--r-- | libc/sysdeps/linux/x86_64/sysdep.h | 349 |
1 files changed, 349 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/x86_64/sysdep.h b/libc/sysdeps/linux/x86_64/sysdep.h new file mode 100644 index 000000000..09bb9268b --- /dev/null +++ b/libc/sysdeps/linux/x86_64/sysdep.h @@ -0,0 +1,349 @@ +/* Copyright (C) 2001-2005, 2007 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 <sys/syscall.h> +#include <common/sysdep.h> + +#ifdef __ASSEMBLER__ + +/* Syntactic details of assembler. */ + +#ifdef HAVE_ELF + +/* ELF uses byte-counts for .align, most others use log2 of count of bytes. */ +#define ALIGNARG(log2) 1<<log2 +/* For ELF we need the `.type' directive to make shared libs work right. */ +#define ASM_TYPE_DIRECTIVE(name,typearg) .type name,typearg; +#define ASM_SIZE_DIRECTIVE(name) .size name,.-name; + +/* In ELF C symbols are asm symbols. */ +#undef NO_UNDERSCORES +#define NO_UNDERSCORES + +#else + +#define ALIGNARG(log2) log2 +#define ASM_TYPE_DIRECTIVE(name,type) /* Nothing is specified. */ +#define ASM_SIZE_DIRECTIVE(name) /* Nothing is specified. */ + +#endif + + +/* Define an entry point visible from C. */ +#define ENTRY(name) \ + ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name); \ + ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function) \ + .align ALIGNARG(4); \ + C_LABEL(name) \ + cfi_startproc; \ + CALL_MCOUNT + +#undef END +#define END(name) \ + cfi_endproc; \ + ASM_SIZE_DIRECTIVE(name) + +/* If compiled for profiling, call `mcount' at the start of each function. */ +#ifdef PROF +/* The mcount code relies on a normal frame pointer being on the stack + to locate our caller, so push one just for its benefit. */ +#define CALL_MCOUNT \ + pushq %rbp; \ + cfi_adjust_cfa_offset(8); \ + movq %rsp, %rbp; \ + cfi_def_cfa_register(%rbp); \ + call JUMPTARGET(mcount); \ + popq %rbp; \ + cfi_def_cfa(rsp,8); +#else +#define CALL_MCOUNT /* Do nothing. */ +#endif + +#ifdef NO_UNDERSCORES +/* Since C identifiers are not normally prefixed with an underscore + on this system, the asm identifier `syscall_error' intrudes on the + C name space. Make sure we use an innocuous name. */ +#define syscall_error __syscall_error +#define mcount _mcount +#endif + +#define PSEUDO(name, syscall_name, args) \ +lose: \ + jmp JUMPTARGET(syscall_error) \ + .globl syscall_error; \ + ENTRY (name) \ + DO_CALL (syscall_name, args); \ + jb lose + +#undef PSEUDO_END +#define PSEUDO_END(name) \ + END (name) + +#undef JUMPTARGET +#ifdef __PIC__ +#define JUMPTARGET(name) name##@PLT +#else +#define JUMPTARGET(name) name +#endif + +/* Local label name for asm code. */ +#ifndef L +# ifdef HAVE_ELF +/* ELF-like local names start with `.L'. */ +# define L(name) .L##name +# else +# define L(name) name +# endif +#endif + +#endif /* __ASSEMBLER__ */ + +/* 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 + +/* This is to help the old kernel headers where __NR_semtimedop is not + available. */ +#ifndef __NR_semtimedop +# define __NR_semtimedop 220 +#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) + +# undef PSEUDO_NOERRNO +# define PSEUDO_NOERRNO(name, syscall_name, args) \ + .text; \ + ENTRY (name) \ + DO_CALL (syscall_name, args) + +# undef PSEUDO_END_NOERRNO +# define PSEUDO_END_NOERRNO(name) \ + END (name) + +# define ret_NOERRNO ret + +# undef PSEUDO_ERRVAL +# define PSEUDO_ERRVAL(name, syscall_name, args) \ + .text; \ + ENTRY (name) \ + DO_CALL (syscall_name, args); \ + negq %rax + +# undef PSEUDO_END_ERRVAL +# define PSEUDO_END_ERRVAL(name) \ + END (name) + +# define ret_ERRVAL ret + +# ifndef __PIC__ +# define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */ +# elif defined(RTLD_PRIVATE_ERRNO) +# define SYSCALL_ERROR_HANDLER \ +0: \ + leaq rtld_errno(%rip), %rcx; \ + xorl %edx, %edx; \ + 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;\ + xorl %edx, %edx; \ + 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: \ + xorl %edx, %edx; \ + subq %rax, %rdx; \ + pushq %rdx; \ + cfi_adjust_cfa_offset(8); \ + call __errno_location@PLT; \ + popq %rdx; \ + cfi_adjust_cfa_offset(-8); \ + 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; \ + xorl %edx, %edx; \ + subq %rax, %rdx; \ + movl %edx, (%rcx); \ + orq $-1, %rax; \ + jmp L(pseudo_end); +# endif /* __PIC__ */ + +/* The Linux/x86-64 kernel expects the system call parameters in + registers according to the following table: + + syscall number rax + arg 1 rdi + arg 2 rsi + arg 3 rdx + arg 4 r10 + arg 5 r8 + arg 6 r9 + + The Linux kernel uses and destroys internally these registers: + return address from + syscall rcx + eflags from syscall r11 + + Normal function call, including calls to the system call stub + functions in the libc, get the first six parameters passed in + registers and the seventh parameter and later on the stack. The + register use is as follows: + + system call number in the DO_CALL macro + arg 1 rdi + arg 2 rsi + arg 3 rdx + arg 4 rcx + arg 5 r8 + arg 6 r9 + + We have to take care that the stack is aligned to 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 \ + movl $SYS_ify (syscall_name), %eax; \ + 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 + +#endif /* __ASSEMBLER__ */ + + +/* Pointer mangling support. */ +#if defined NOT_IN_libc && defined IS_IN_rtld +/* We cannot use the thread descriptor because in ld.so we use setjmp + earlier than the descriptor is initialized. */ +# ifdef __ASSEMBLER__ +# define PTR_MANGLE(reg) xorq __pointer_chk_guard_local(%rip), reg; \ + rolq $17, reg +# define PTR_DEMANGLE(reg) rorq $17, reg; \ + xorq __pointer_chk_guard_local(%rip), reg +# else +# define PTR_MANGLE(reg) __asm__ ("xorq __pointer_chk_guard_local(%%rip), %0\n" \ + "rolq $17, %0" \ + : "=r" (reg) : "0" (reg)) +# define PTR_DEMANGLE(reg) __asm__ ("rorq $17, %0\n" \ + "xorq __pointer_chk_guard_local(%%rip), %0" \ + : "=r" (reg) : "0" (reg)) +# endif +#else +# ifdef __ASSEMBLER__ +# define PTR_MANGLE(reg) xorq %fs:POINTER_GUARD, reg; \ + rolq $17, reg +# define PTR_DEMANGLE(reg) rorq $17, reg; \ + xorq %fs:POINTER_GUARD, reg +# else +# define PTR_MANGLE(var) __asm__ ("xorq %%fs:%c2, %0\n" \ + "rolq $17, %0" \ + : "=r" (var) \ + : "0" (var), \ + "i" (offsetof (tcbhead_t, \ + pointer_guard))) +# define PTR_DEMANGLE(var) __asm__ ("rorq $17, %0\n" \ + "xorq %%fs:%c2, %0" \ + : "=r" (var) \ + : "0" (var), \ + "i" (offsetof (tcbhead_t, \ + pointer_guard))) +# endif +#endif + +#endif /* linux/x86_64/sysdep.h */ |