sysdeps/unix/sysv/linux/i386/socket.S

   1 /* Copyright (C) 1995-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sysdep-cancel.h>
  19 #include <socketcall.h>
  20 #include <tls.h>
  21
  22 #define P(a, b) P2(a, b)
  23 #define P2(a, b) a##b
  24
  25         .text
  26 /* The socket-oriented system calls are handled unusally in Linux/i386.
  27    They are all gated through the single `socketcall' system call number.
  28    `socketcall' takes two arguments: the first is the subcode, specifying
  29    which socket function is being called; and the second is a pointer to
  30    the arguments to the specific function.
  31
  32    The .S files for the other calls just #define socket and #include this.  */
  33
  34 #ifndef __socket
  35 # ifndef NO_WEAK_ALIAS
  36 #  define __socket P(__,socket)
  37 # else
  38 #  define __socket socket
  39 # endif
  40 #endif
  41
  42 .globl __socket
  43 ENTRY (__socket)
  44 #if defined NEED_CANCELLATION && defined CENABLE
  45         SINGLE_THREAD_P
  46         jne 1f
  47 #endif
  48
  49         /* Save registers.  */
  50         movl %ebx, %edx
  51         cfi_register (3, 2)
  52
  53         movl $SYS_ify(socketcall), %eax /* System call number in %eax.  */
  54
  55         /* Use ## so `socket' is a separate token that might be #define'd.  */
  56         movl $P(SOCKOP_,socket), %ebx   /* Subcode is first arg to syscall.  */
  57         lea 4(%esp), %ecx               /* Address of args is 2nd arg.  */
  58
  59         /* Do the system call trap.  */
  60         ENTER_KERNEL
  61
  62         /* Restore registers.  */
  63         movl %edx, %ebx
  64         cfi_restore (3)
  65
  66         /* %eax is < 0 if there was an error.  */
  67         cmpl $-125, %eax
  68         jae SYSCALL_ERROR_LABEL
  69
  70         /* Successful; return the syscall's value.  */
  71         ret
  72
  73
  74 #if defined NEED_CANCELLATION && defined CENABLE
  75         /* We need one more register.  */
  76 1:      pushl %esi
  77         cfi_adjust_cfa_offset(4)
  78
  79         /* Enable asynchronous cancellation.  */
  80         CENABLE
  81         movl %eax, %esi
  82         cfi_offset(6, -8)               /* %esi */
  83
  84         /* Save registers.  */
  85         movl %ebx, %edx
  86         cfi_register (3, 2)
  87
  88         movl $SYS_ify(socketcall), %eax /* System call number in %eax.  */
  89
  90         /* Use ## so `socket' is a separate token that might be #define'd.  */
  91         movl $P(SOCKOP_,socket), %ebx   /* Subcode is first arg to syscall.  */
  92         lea 8(%esp), %ecx               /* Address of args is 2nd arg.  */
  93
  94         /* Do the system call trap.  */
  95         ENTER_KERNEL
  96
  97         /* Restore registers.  */
  98         movl %edx, %ebx
  99         cfi_restore (3)
 100
 101         /* Restore the cancellation.  */
 102         xchgl %esi, %eax
 103         CDISABLE
 104
 105         /* Restore registers.  */
 106         movl %esi, %eax
 107         popl %esi
 108         cfi_restore (6)
 109         cfi_adjust_cfa_offset(-4)
 110
 111         /* %eax is < 0 if there was an error.  */
 112         cmpl $-125, %eax
 113         jae SYSCALL_ERROR_LABEL
 114
 115         /* Successful; return the syscall's value.  */
 116         ret
 117 #endif
 118 PSEUDO_END (__socket)
 119
 120 #ifndef NO_WEAK_ALIAS
 121 weak_alias (__socket, socket)
 122 #endif