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- /* 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 */
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