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3a370de88f
2003-06-06 Ulrich Drepper <drepper@redhat.com> * sysdeps/unix/sysv/linux/i386/sysdep.h (ASMFMT_2): Only allow %edx for first parameter. This means no pushl and therefore the unwind info isn't screwed up.
435 lines
14 KiB
C
435 lines
14 KiB
C
/* Copyright (C) 1992,1993,1995-2000,2002,2003 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper, <drepper@gnu.org>, August 1995.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#ifndef _LINUX_I386_SYSDEP_H
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#define _LINUX_I386_SYSDEP_H 1
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/* There is some commonality. */
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#include <sysdeps/unix/i386/sysdep.h>
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#include <bp-sym.h>
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#include <bp-asm.h>
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/* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO. */
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#include <dl-sysdep.h>
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#include <tls.h>
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/* For Linux we can use the system call table in the header file
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/usr/include/asm/unistd.h
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of the kernel. But these symbols do not follow the SYS_* syntax
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so we have to redefine the `SYS_ify' macro here. */
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#undef SYS_ify
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#define SYS_ify(syscall_name) __NR_##syscall_name
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#if defined USE_DL_SYSINFO \
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&& (!defined NOT_IN_libc || defined IS_IN_libpthread)
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# define I386_USE_SYSENTER 1
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#else
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# undef I386_USE_SYSENTER
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#endif
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#ifdef __ASSEMBLER__
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/* Linux uses a negative return value to indicate syscall errors,
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unlike most Unices, which use the condition codes' carry flag.
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Since version 2.1 the return value of a system call might be
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negative even if the call succeeded. E.g., the `lseek' system call
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might return a large offset. Therefore we must not anymore test
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for < 0, but test for a real error by making sure the value in %eax
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is a real error number. Linus said he will make sure the no syscall
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returns a value in -1 .. -4095 as a valid result so we can savely
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test with -4095. */
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/* We don't want the label for the error handle to be global when we define
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it here. */
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#ifdef PIC
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# define SYSCALL_ERROR_LABEL 0f
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#else
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# define SYSCALL_ERROR_LABEL syscall_error
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#endif
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#undef PSEUDO
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#define PSEUDO(name, syscall_name, args) \
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.text; \
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ENTRY (name) \
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DO_CALL (syscall_name, args); \
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cmpl $-4095, %eax; \
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jae SYSCALL_ERROR_LABEL; \
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L(pseudo_end):
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#undef PSEUDO_END
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#define PSEUDO_END(name) \
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SYSCALL_ERROR_HANDLER \
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END (name)
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#undef PSEUDO_NOERRNO
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#define PSEUDO_NOERRNO(name, syscall_name, args) \
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.text; \
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ENTRY (name) \
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DO_CALL (syscall_name, args)
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#undef PSEUDO_END_NOERRNO
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#define PSEUDO_END_NOERRNO(name) \
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END (name)
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#define ret_NOERRNO ret
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#ifndef PIC
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# define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
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#else
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# ifndef HAVE_HIDDEN
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# define SETUP_PIC_REG(reg) \
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call 1f; \
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.subsection 1; \
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1:movl (%esp), %e##reg; \
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ret; \
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.previous
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# else
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# define SETUP_PIC_REG(reg) \
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.section .gnu.linkonce.t.__i686.get_pc_thunk.reg,"ax",@progbits; \
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.globl __i686.get_pc_thunk.reg; \
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.hidden __i686.get_pc_thunk.reg; \
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.type __i686.get_pc_thunk.reg,@function; \
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__i686.get_pc_thunk.reg: \
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movl (%esp), %e##reg; \
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ret; \
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.size __i686.get_pc_thunk.reg, . - __i686.get_pc_thunk.reg; \
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.previous; \
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call __i686.get_pc_thunk.reg
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# endif
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# if RTLD_PRIVATE_ERRNO
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# define SYSCALL_ERROR_HANDLER \
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0:SETUP_PIC_REG(cx); \
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addl $_GLOBAL_OFFSET_TABLE_, %ecx; \
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xorl %edx, %edx; \
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subl %eax, %edx; \
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movl %edx, errno@GOTOFF(%ecx); \
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orl $-1, %eax; \
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jmp L(pseudo_end);
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# elif defined _LIBC_REENTRANT
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# if USE___THREAD
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# ifndef NOT_IN_libc
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# define SYSCALL_ERROR_ERRNO __libc_errno
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# else
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# define SYSCALL_ERROR_ERRNO errno
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# endif
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# define SYSCALL_ERROR_HANDLER \
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0:SETUP_PIC_REG (cx); \
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addl $_GLOBAL_OFFSET_TABLE_, %ecx; \
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movl SYSCALL_ERROR_ERRNO@GOTNTPOFF(%ecx), %ecx; \
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xorl %edx, %edx; \
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subl %eax, %edx; \
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movl %edx, %gs:0(%ecx); \
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orl $-1, %eax; \
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jmp L(pseudo_end);
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# else
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# define SYSCALL_ERROR_HANDLER \
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0:pushl %ebx; \
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SETUP_PIC_REG (bx); \
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addl $_GLOBAL_OFFSET_TABLE_, %ebx; \
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xorl %edx, %edx; \
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subl %eax, %edx; \
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pushl %edx; \
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PUSH_ERRNO_LOCATION_RETURN; \
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call BP_SYM (__errno_location)@PLT; \
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POP_ERRNO_LOCATION_RETURN; \
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popl %ecx; \
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popl %ebx; \
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movl %ecx, (%eax); \
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orl $-1, %eax; \
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jmp L(pseudo_end);
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/* A quick note: it is assumed that the call to `__errno_location' does
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not modify the stack! */
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# endif
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# else
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/* Store (- %eax) into errno through the GOT. */
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# define SYSCALL_ERROR_HANDLER \
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0:SETUP_PIC_REG(cx); \
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addl $_GLOBAL_OFFSET_TABLE_, %ecx; \
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xorl %edx, %edx; \
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subl %eax, %edx; \
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movl errno@GOT(%ecx), %ecx; \
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movl %edx, (%ecx); \
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orl $-1, %eax; \
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jmp L(pseudo_end);
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# endif /* _LIBC_REENTRANT */
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#endif /* PIC */
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/* The original calling convention for system calls on Linux/i386 is
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to use int $0x80. */
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#ifdef I386_USE_SYSENTER
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# ifdef SHARED
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# define ENTER_KERNEL call *%gs:SYSINFO_OFFSET
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# else
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# define ENTER_KERNEL call *_dl_sysinfo
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# endif
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#else
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# define ENTER_KERNEL int $0x80
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#endif
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/* Linux takes system call arguments in registers:
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syscall number %eax call-clobbered
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arg 1 %ebx call-saved
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arg 2 %ecx call-clobbered
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arg 3 %edx call-clobbered
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arg 4 %esi call-saved
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arg 5 %edi call-saved
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The stack layout upon entering the function is:
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20(%esp) Arg# 5
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16(%esp) Arg# 4
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12(%esp) Arg# 3
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8(%esp) Arg# 2
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4(%esp) Arg# 1
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(%esp) Return address
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(Of course a function with say 3 arguments does not have entries for
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arguments 4 and 5.)
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The following code tries hard to be optimal. A general assumption
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(which is true according to the data books I have) is that
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2 * xchg is more expensive than pushl + movl + popl
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Beside this a neat trick is used. The calling conventions for Linux
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tell that among the registers used for parameters %ecx and %edx need
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not be saved. Beside this we may clobber this registers even when
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they are not used for parameter passing.
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As a result one can see below that we save the content of the %ebx
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register in the %edx register when we have less than 3 arguments
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(2 * movl is less expensive than pushl + popl).
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Second unlike for the other registers we don't save the content of
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%ecx and %edx when we have more than 1 and 2 registers resp.
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The code below might look a bit long but we have to take care for
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the pipelined processors (i586). Here the `pushl' and `popl'
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instructions are marked as NP (not pairable) but the exception is
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two consecutive of these instruction. This gives no penalty on
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other processors though. */
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#undef DO_CALL
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#define DO_CALL(syscall_name, args) \
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PUSHARGS_##args \
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DOARGS_##args \
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movl $SYS_ify (syscall_name), %eax; \
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ENTER_KERNEL \
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POPARGS_##args
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#define PUSHARGS_0 /* No arguments to push. */
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#define DOARGS_0 /* No arguments to frob. */
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#define POPARGS_0 /* No arguments to pop. */
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#define _PUSHARGS_0 /* No arguments to push. */
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#define _DOARGS_0(n) /* No arguments to frob. */
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#define _POPARGS_0 /* No arguments to pop. */
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#define PUSHARGS_1 movl %ebx, %edx; L(SAVEBX1): PUSHARGS_0
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#define DOARGS_1 _DOARGS_1 (4)
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#define POPARGS_1 POPARGS_0; movl %edx, %ebx; L(RESTBX1):
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#define _PUSHARGS_1 pushl %ebx; L(PUSHBX1): _PUSHARGS_0
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#define _DOARGS_1(n) movl n(%esp), %ebx; _DOARGS_0(n-4)
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#define _POPARGS_1 _POPARGS_0; popl %ebx; L(POPBX1):
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#define PUSHARGS_2 PUSHARGS_1
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#define DOARGS_2 _DOARGS_2 (8)
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#define POPARGS_2 POPARGS_1
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#define _PUSHARGS_2 _PUSHARGS_1
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#define _DOARGS_2(n) movl n(%esp), %ecx; _DOARGS_1 (n-4)
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#define _POPARGS_2 _POPARGS_1
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#define PUSHARGS_3 _PUSHARGS_2
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#define DOARGS_3 _DOARGS_3 (16)
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#define POPARGS_3 _POPARGS_3
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#define _PUSHARGS_3 _PUSHARGS_2
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#define _DOARGS_3(n) movl n(%esp), %edx; _DOARGS_2 (n-4)
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#define _POPARGS_3 _POPARGS_2
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#define PUSHARGS_4 _PUSHARGS_4
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#define DOARGS_4 _DOARGS_4 (24)
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#define POPARGS_4 _POPARGS_4
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#define _PUSHARGS_4 pushl %esi; L(PUSHSI1): _PUSHARGS_3
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#define _DOARGS_4(n) movl n(%esp), %esi; _DOARGS_3 (n-4)
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#define _POPARGS_4 _POPARGS_3; popl %esi; L(POPSI1):
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#define PUSHARGS_5 _PUSHARGS_5
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#define DOARGS_5 _DOARGS_5 (32)
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#define POPARGS_5 _POPARGS_5
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#define _PUSHARGS_5 pushl %edi; L(PUSHDI1): _PUSHARGS_4
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#define _DOARGS_5(n) movl n(%esp), %edi; _DOARGS_4 (n-4)
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#define _POPARGS_5 _POPARGS_4; popl %edi; L(POPDI1):
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#else /* !__ASSEMBLER__ */
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/* We need some help from the assembler to generate optimal code. We
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define some macros here which later will be used. */
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asm (".L__X'%ebx = 1\n\t"
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".L__X'%ecx = 2\n\t"
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".L__X'%edx = 2\n\t"
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".L__X'%eax = 3\n\t"
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".L__X'%esi = 3\n\t"
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".L__X'%edi = 3\n\t"
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".L__X'%ebp = 3\n\t"
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".L__X'%esp = 3\n\t"
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".macro bpushl name reg\n\t"
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".if 1 - \\name\n\t"
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".if 2 - \\name\n\t"
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"pushl %ebx\n\t"
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".else\n\t"
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"xchgl \\reg, %ebx\n\t"
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".endif\n\t"
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".endif\n\t"
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".endm\n\t"
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".macro bpopl name reg\n\t"
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".if 1 - \\name\n\t"
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".if 2 - \\name\n\t"
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"popl %ebx\n\t"
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".else\n\t"
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"xchgl \\reg, %ebx\n\t"
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".endif\n\t"
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".endif\n\t"
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".endm\n\t"
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".macro bmovl name reg\n\t"
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".if 1 - \\name\n\t"
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".if 2 - \\name\n\t"
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"movl \\reg, %ebx\n\t"
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".endif\n\t"
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".endif\n\t"
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".endm\n\t");
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/* Define a macro which expands inline into the wrapper code for a system
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call. */
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#undef INLINE_SYSCALL
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#define INLINE_SYSCALL(name, nr, args...) \
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({ \
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unsigned int resultvar = INTERNAL_SYSCALL (name, , nr, args); \
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if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (resultvar, ), 0)) \
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{ \
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__set_errno (INTERNAL_SYSCALL_ERRNO (resultvar, )); \
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resultvar = 0xffffffff; \
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} \
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(int) resultvar; })
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/* Define a macro which expands inline into the wrapper code for a system
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call. This use is for internal calls that do not need to handle errors
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normally. It will never touch errno. This returns just what the kernel
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gave back. */
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#undef INTERNAL_SYSCALL
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#ifdef I386_USE_SYSENTER
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# ifdef SHARED
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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({ \
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unsigned int resultvar; \
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asm volatile ( \
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LOADARGS_##nr \
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"movl %1, %%eax\n\t" \
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"call *%%gs:%P2\n\t" \
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RESTOREARGS_##nr \
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: "=a" (resultvar) \
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: "i" (__NR_##name), "i" (offsetof (tcbhead_t, sysinfo)) \
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ASMFMT_##nr(args) : "memory", "cc"); \
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(int) resultvar; })
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# else
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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({ \
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unsigned int resultvar; \
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asm volatile ( \
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LOADARGS_##nr \
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"movl %1, %%eax\n\t" \
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"call *_dl_sysinfo\n\t" \
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RESTOREARGS_##nr \
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: "=a" (resultvar) \
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: "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc"); \
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(int) resultvar; })
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# endif
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#else
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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({ \
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unsigned int resultvar; \
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asm volatile ( \
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LOADARGS_##nr \
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"movl %1, %%eax\n\t" \
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"int $0x80\n\t" \
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RESTOREARGS_##nr \
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: "=a" (resultvar) \
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: "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc"); \
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(int) resultvar; })
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#endif
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#undef INTERNAL_SYSCALL_DECL
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#define INTERNAL_SYSCALL_DECL(err) do { } while (0)
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#undef INTERNAL_SYSCALL_ERROR_P
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#define INTERNAL_SYSCALL_ERROR_P(val, err) \
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((unsigned int) (val) >= 0xfffff001u)
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#undef INTERNAL_SYSCALL_ERRNO
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#define INTERNAL_SYSCALL_ERRNO(val, err) (-(val))
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#define LOADARGS_0
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#if defined I386_USE_SYSENTER && defined SHARED
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# define LOADARGS_1 \
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"bpushl .L__X'%k3, %k3\n\t" \
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"bmovl .L__X'%k3, %k3\n\t"
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#else
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# define LOADARGS_1 \
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"bpushl .L__X'%k2, %k2\n\t" \
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"bmovl .L__X'%k2, %k2\n\t"
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#endif
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#define LOADARGS_2 LOADARGS_1
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#define LOADARGS_3 LOADARGS_1
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#define LOADARGS_4 LOADARGS_1
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#define LOADARGS_5 LOADARGS_1
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#define RESTOREARGS_0
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#if defined I386_USE_SYSENTER && defined SHARED
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# define RESTOREARGS_1 \
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"bpopl .L__X'%k3, %k3\n\t"
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#else
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# define RESTOREARGS_1 \
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"bpopl .L__X'%k2, %k2\n\t"
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#endif
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#define RESTOREARGS_2 RESTOREARGS_1
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#define RESTOREARGS_3 RESTOREARGS_1
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#define RESTOREARGS_4 RESTOREARGS_1
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#define RESTOREARGS_5 RESTOREARGS_1
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#define ASMFMT_0()
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#define ASMFMT_1(arg1) \
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, "acdSD" (arg1)
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#define ASMFMT_2(arg1, arg2) \
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, "d" (arg1), "c" (arg2)
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#define ASMFMT_3(arg1, arg2, arg3) \
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, "aSD" (arg1), "c" (arg2), "d" (arg3)
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#define ASMFMT_4(arg1, arg2, arg3, arg4) \
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, "aD" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
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#define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
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, "a" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
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#endif /* __ASSEMBLER__ */
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#endif /* linux/i386/sysdep.h */
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