diff options
Diffstat (limited to 'libc/sysdeps/linux')
| -rw-r--r-- | libc/sysdeps/linux/i386/sysdep.h | 336 |
1 files changed, 336 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/i386/sysdep.h b/libc/sysdeps/linux/i386/sysdep.h new file mode 100644 index 000000000..ffbde7d96 --- /dev/null +++ b/libc/sysdeps/linux/i386/sysdep.h @@ -0,0 +1,336 @@ +/* Copyright (C) 1992,1993,1995-2000,2002-2006,2007 + Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper, <drepper@gnu.org>, August 1995. + + 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_I386_SYSDEP_H +#define _LINUX_I386_SYSDEP_H 1 + +#include <sys/syscall.h> +#include <sysdeps/i386/sysdep.h> + +#ifndef offsetof +# define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) +#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 + +#if defined USE_DL_SYSINFO \ + && (!defined NOT_IN_libc || defined IS_IN_libpthread) +# define I386_USE_SYSENTER 1 +#else +# undef I386_USE_SYSENTER +#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); \ + cmpl $-4095, %eax; \ + 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 + +/* The function has to return the error code. */ +#undef PSEUDO_ERRVAL +#define PSEUDO_ERRVAL(name, syscall_name, args) \ + .text; \ + ENTRY (name) \ + DO_CALL (syscall_name, args); \ + negl %eax + +#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. */ +#else + +# ifdef RTLD_PRIVATE_ERRNO +# define SYSCALL_ERROR_HANDLER \ +0:SETUP_PIC_REG(cx); \ + addl $_GLOBAL_OFFSET_TABLE_, %ecx; \ + xorl %edx, %edx; \ + subl %eax, %edx; \ + movl %edx, rtld_errno@GOTOFF(%ecx); \ + orl $-1, %eax; \ + jmp L(pseudo_end); + +# elif defined _LIBC_REENTRANT + +# if USE___THREAD +# ifndef NOT_IN_libc +# define SYSCALL_ERROR_ERRNO __libc_errno +# else +# define SYSCALL_ERROR_ERRNO errno +# endif +# define SYSCALL_ERROR_HANDLER \ +0:SETUP_PIC_REG (cx); \ + addl $_GLOBAL_OFFSET_TABLE_, %ecx; \ + movl SYSCALL_ERROR_ERRNO@GOTNTPOFF(%ecx), %ecx; \ + xorl %edx, %edx; \ + subl %eax, %edx; \ + SYSCALL_ERROR_HANDLER_TLS_STORE (%edx, %ecx); \ + orl $-1, %eax; \ + jmp L(pseudo_end); +# ifndef NO_TLS_DIRECT_SEG_REFS +# define SYSCALL_ERROR_HANDLER_TLS_STORE(src, destoff) \ + movl src, %gs:(destoff) +# else +# define SYSCALL_ERROR_HANDLER_TLS_STORE(src, destoff) \ + addl %gs:0, destoff; \ + movl src, (destoff) +# endif +# else +# define SYSCALL_ERROR_HANDLER \ +0:pushl %ebx; \ + cfi_adjust_cfa_offset (4); \ + cfi_rel_offset (ebx, 0); \ + SETUP_PIC_REG (bx); \ + addl $_GLOBAL_OFFSET_TABLE_, %ebx; \ + xorl %edx, %edx; \ + subl %eax, %edx; \ + pushl %edx; \ + cfi_adjust_cfa_offset (4); \ + call __errno_location@PLT; \ + popl %ecx; \ + cfi_adjust_cfa_offset (-4); \ + popl %ebx; \ + cfi_adjust_cfa_offset (-4); \ + cfi_restore (ebx); \ + movl %ecx, (%eax); \ + orl $-1, %eax; \ + jmp L(pseudo_end); +/* A quick note: it is assumed that the call to `__errno_location' does + not modify the stack! */ +# endif +# else +/* Store (- %eax) into errno through the GOT. */ +# define SYSCALL_ERROR_HANDLER \ +0:SETUP_PIC_REG(cx); \ + addl $_GLOBAL_OFFSET_TABLE_, %ecx; \ + xorl %edx, %edx; \ + subl %eax, %edx; \ + movl errno@GOT(%ecx), %ecx; \ + movl %edx, (%ecx); \ + orl $-1, %eax; \ + jmp L(pseudo_end); +# endif /* _LIBC_REENTRANT */ +#endif /* __PIC__ */ + + +/* The original calling convention for system calls on Linux/i386 is + to use int $0x80. */ +#ifdef I386_USE_SYSENTER +# ifdef SHARED +# define ENTER_KERNEL call *%gs:SYSINFO_OFFSET +# else +# define ENTER_KERNEL call *_dl_sysinfo +# endif +#else +# define ENTER_KERNEL int $0x80 +#endif + +/* Linux takes system call arguments in registers: + + syscall number %eax call-clobbered + arg 1 %ebx call-saved + arg 2 %ecx call-clobbered + arg 3 %edx call-clobbered + arg 4 %esi call-saved + arg 5 %edi call-saved + arg 6 %ebp call-saved + + The stack layout upon entering the function is: + + 24(%esp) Arg# 6 + 20(%esp) Arg# 5 + 16(%esp) Arg# 4 + 12(%esp) Arg# 3 + 8(%esp) Arg# 2 + 4(%esp) Arg# 1 + (%esp) Return address + + (Of course a function with say 3 arguments does not have entries for + arguments 4, 5, and 6.) + + The following code tries hard to be optimal. A general assumption + (which is true according to the data books I have) is that + + 2 * xchg is more expensive than pushl + movl + popl + + Beside this a neat trick is used. The calling conventions for Linux + tell that among the registers used for parameters %ecx and %edx need + not be saved. Beside this we may clobber this registers even when + they are not used for parameter passing. + + As a result one can see below that we save the content of the %ebx + register in the %edx register when we have less than 3 arguments + (2 * movl is less expensive than pushl + popl). + + Second unlike for the other registers we don't save the content of + %ecx and %edx when we have more than 1 and 2 registers resp. + + The code below might look a bit long but we have to take care for + the pipelined processors (i586). Here the `pushl' and `popl' + instructions are marked as NP (not pairable) but the exception is + two consecutive of these instruction. This gives no penalty on + other processors though. */ + +#undef DO_CALL +#define DO_CALL(syscall_name, args) \ + PUSHARGS_##args \ + DOARGS_##args \ + movl $SYS_ify (syscall_name), %eax; \ + ENTER_KERNEL \ + POPARGS_##args + +#define PUSHARGS_0 /* No arguments to push. */ +#define DOARGS_0 /* No arguments to frob. */ +#define POPARGS_0 /* No arguments to pop. */ +#define _PUSHARGS_0 /* No arguments to push. */ +#define _DOARGS_0(n) /* No arguments to frob. */ +#define _POPARGS_0 /* No arguments to pop. */ + +#define PUSHARGS_1 movl %ebx, %edx; L(SAVEBX1): PUSHARGS_0 +#define DOARGS_1 _DOARGS_1 (4) +#define POPARGS_1 POPARGS_0; movl %edx, %ebx; L(RESTBX1): +#define _PUSHARGS_1 pushl %ebx; cfi_adjust_cfa_offset (4); \ + cfi_rel_offset (ebx, 0); L(PUSHBX1): _PUSHARGS_0 +#define _DOARGS_1(n) movl n(%esp), %ebx; _DOARGS_0(n-4) +#define _POPARGS_1 _POPARGS_0; popl %ebx; cfi_adjust_cfa_offset (-4); \ + cfi_restore (ebx); L(POPBX1): + +#define PUSHARGS_2 PUSHARGS_1 +#define DOARGS_2 _DOARGS_2 (8) +#define POPARGS_2 POPARGS_1 +#define _PUSHARGS_2 _PUSHARGS_1 +#define _DOARGS_2(n) movl n(%esp), %ecx; _DOARGS_1 (n-4) +#define _POPARGS_2 _POPARGS_1 + +#define PUSHARGS_3 _PUSHARGS_2 +#define DOARGS_3 _DOARGS_3 (16) +#define POPARGS_3 _POPARGS_3 +#define _PUSHARGS_3 _PUSHARGS_2 +#define _DOARGS_3(n) movl n(%esp), %edx; _DOARGS_2 (n-4) +#define _POPARGS_3 _POPARGS_2 + +#define PUSHARGS_4 _PUSHARGS_4 +#define DOARGS_4 _DOARGS_4 (24) +#define POPARGS_4 _POPARGS_4 +#define _PUSHARGS_4 pushl %esi; cfi_adjust_cfa_offset (4); \ + cfi_rel_offset (esi, 0); L(PUSHSI1): _PUSHARGS_3 +#define _DOARGS_4(n) movl n(%esp), %esi; _DOARGS_3 (n-4) +#define _POPARGS_4 _POPARGS_3; popl %esi; cfi_adjust_cfa_offset (-4); \ + cfi_restore (esi); L(POPSI1): + +#define PUSHARGS_5 _PUSHARGS_5 +#define DOARGS_5 _DOARGS_5 (32) +#define POPARGS_5 _POPARGS_5 +#define _PUSHARGS_5 pushl %edi; cfi_adjust_cfa_offset (4); \ + cfi_rel_offset (edi, 0); L(PUSHDI1): _PUSHARGS_4 +#define _DOARGS_5(n) movl n(%esp), %edi; _DOARGS_4 (n-4) +#define _POPARGS_5 _POPARGS_4; popl %edi; cfi_adjust_cfa_offset (-4); \ + cfi_restore (edi); L(POPDI1): + +#define PUSHARGS_6 _PUSHARGS_6 +#define DOARGS_6 _DOARGS_6 (40) +#define POPARGS_6 _POPARGS_6 +#define _PUSHARGS_6 pushl %ebp; cfi_adjust_cfa_offset (4); \ + cfi_rel_offset (ebp, 0); L(PUSHBP1): _PUSHARGS_5 +#define _DOARGS_6(n) movl n(%esp), %ebp; _DOARGS_5 (n-4) +#define _POPARGS_6 _POPARGS_5; popl %ebp; cfi_adjust_cfa_offset (-4); \ + cfi_restore (ebp); L(POPBP1): + +#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. Using a global variable + is too complicated here since we have no PC-relative addressing mode. */ +#else +# ifdef __ASSEMBLER__ +# define PTR_MANGLE(reg) xorl %gs:POINTER_GUARD, reg; \ + roll $9, reg +# define PTR_DEMANGLE(reg) rorl $9, reg; \ + xorl %gs:POINTER_GUARD, reg +# else +# define PTR_MANGLE(var) __asm__ ("xorl %%gs:%c2, %0\n" \ + "roll $9, %0" \ + : "=r" (var) \ + : "0" (var), \ + "i" (offsetof (tcbhead_t, \ + pointer_guard))) +# define PTR_DEMANGLE(var) __asm__ ("rorl $9, %0\n" \ + "xorl %%gs:%c2, %0" \ + : "=r" (var) \ + : "0" (var), \ + "i" (offsetof (tcbhead_t, \ + pointer_guard))) +# endif +#endif + +#endif /* linux/i386/sysdep.h */ |