| /* 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 <common/sysdep.h> |
| |
| #ifdef __ASSEMBLER__ |
| |
| /* Syntactic details of assembler. */ |
| |
| /* 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 |
| |
| /* Define an entry point visible from C. |
| |
| There is currently a bug in gdb which prevents us from specifying |
| incomplete stabs information. Fake some entries here which specify |
| the current source file. */ |
| #define ENTRY(name) \ |
| STABS_CURRENT_FILE1("") \ |
| STABS_CURRENT_FILE(name) \ |
| ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name); \ |
| ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function) \ |
| .align ALIGNARG(4); \ |
| STABS_FUN(name) \ |
| C_LABEL(name) \ |
| cfi_startproc; \ |
| CALL_MCOUNT |
| |
| #undef END |
| #define END(name) \ |
| cfi_endproc; \ |
| ASM_SIZE_DIRECTIVE(name) \ |
| STABS_FUN_END(name) |
| |
| #ifdef HAVE_CPP_ASM_DEBUGINFO |
| /* Disable that goop, because we just pass -g through to the assembler |
| and it generates proper line number information directly. */ |
| # define STABS_CURRENT_FILE1(name) |
| # define STABS_CURRENT_FILE(name) |
| # define STABS_FUN(name) |
| # define STABS_FUN_END(name) |
| #else |
| /* Remove the following two lines once the gdb bug is fixed. */ |
| #define STABS_CURRENT_FILE(name) \ |
| STABS_CURRENT_FILE1 (#name) |
| #define STABS_CURRENT_FILE1(name) \ |
| 1: .stabs name,100,0,0,1b; |
| /* Emit stabs definition lines. We use F(0,1) and define t(0,1) as `int', |
| the same way gcc does it. */ |
| #define STABS_FUN(name) STABS_FUN2(name, name##:F(0,1)) |
| #define STABS_FUN2(name, namestr) \ |
| .stabs "int:t(0,1)=r(0,1);-2147483648;2147483647;",128,0,0,0; \ |
| .stabs #namestr,36,0,0,name; |
| #define STABS_FUN_END(name) \ |
| 1: .stabs "",36,0,0,1b-name; |
| #endif |
| |
| /* 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 \ |
| pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \ |
| cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \ |
| popl %ebp; cfi_def_cfa (esp, 4); |
| #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 |
| |
| #undef JUMPTARGET |
| #ifdef __PIC__ |
| #define JUMPTARGET(name) name##@PLT |
| #define SYSCALL_PIC_SETUP \ |
| pushl %ebx; \ |
| cfi_adjust_cfa_offset (4); \ |
| call 0f; \ |
| 0: popl %ebx; \ |
| cfi_adjust_cfa_offset (-4); \ |
| addl $_GLOBAL_OFFSET_TABLE+[.-0b], %ebx; |
| |
| |
| # define SETUP_PIC_REG(reg) \ |
| .ifndef __x86.get_pc_thunk.reg; \ |
| .section .gnu.linkonce.t.__x86.get_pc_thunk.reg,"ax",@progbits; \ |
| .globl __x86.get_pc_thunk.reg; \ |
| .hidden __x86.get_pc_thunk.reg; \ |
| .type __x86.get_pc_thunk.reg,@function; \ |
| __x86.get_pc_thunk.reg: \ |
| movl (%esp), %e##reg; \ |
| ret; \ |
| .size __x86.get_pc_thunk.reg, . - __x86.get_pc_thunk.reg; \ |
| .previous; \ |
| .endif; \ |
| call __x86.get_pc_thunk.reg |
| |
| # define LOAD_PIC_REG(reg) \ |
| SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg |
| |
| #else |
| #define JUMPTARGET(name) name |
| #define SYSCALL_PIC_SETUP /* Nothing. */ |
| #endif |
| |
| /* Local label name for asm code. */ |
| #ifndef L |
| #ifdef HAVE_ELF |
| #define L(name) .L##name |
| #else |
| #define L(name) name |
| #endif |
| #endif |
| |
| /* Avoid conflics with thunk section */ |
| #undef __i686 |
| #endif /* __ASSEMBLER__ */ |
| |
| #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 defined 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 */ |