sysdeps/unix/sysv/linux/mips/clone.S

   1 /* Copyright (C) 1996-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ralf Bächle <ralf@linux-mips.org>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* clone() is even more special than fork() as it mucks with stacks
  20    and invokes a function in the right context after its all over.  */
  21
  22 #include <sys/asm.h>
  23 #include <sysdep.h>
  24 #define _ERRNO_H        1
  25 #include <bits/errno.h>
  26 #include <tls.h>
  27
  28 /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
  29              void *parent_tidptr, void *tls, void *child_tidptr) */
  30
  31         .text
  32         .set            nomips16
  33 #if _MIPS_SIM == _ABIO32
  34 # define EXTRA_LOCALS 1
  35 #else
  36 # define EXTRA_LOCALS 0
  37 #endif
  38 LOCALSZ= 4
  39 FRAMESZ= (((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK
  40 GPOFF= FRAMESZ-(1*SZREG)
  41 NESTED(__clone,4*SZREG,sp)
  42 #ifdef __PIC__
  43         SETUP_GP
  44 #endif
  45         PTR_SUBU sp, FRAMESZ
  46         cfi_adjust_cfa_offset (FRAMESZ)
  47         SETUP_GP64_STACK (GPOFF, __clone)
  48 #ifdef __PIC__
  49         SAVE_GP (GPOFF)
  50 #endif
  51 #ifdef PROF
  52         .set            noat
  53         move            $1,ra
  54         jal             _mcount
  55         .set            at
  56 #endif
  57
  58
  59         /* Sanity check arguments.  */
  60         li              v0,EINVAL
  61         beqz            a0,L(error)     /* No NULL function pointers.  */
  62         beqz            a1,L(error)     /* No NULL stack pointers.  */
  63
  64         PTR_SUBU        a1,32           /* Reserve argument save space.  */
  65         PTR_S           a0,0(a1)        /* Save function pointer.  */
  66         PTR_S           a3,PTRSIZE(a1)  /* Save argument pointer.  */
  67         LONG_S          a2,(PTRSIZE*2)(a1)      /* Save clone flags.  */
  68
  69         move            a0,a2
  70
  71         /* Shuffle in the last three arguments - arguments 5, 6, and 7 to
  72            this function, but arguments 3, 4, and 5 to the syscall.  */
  73 #if _MIPS_SIM == _ABIO32
  74         PTR_L           a2,(FRAMESZ+PTRSIZE+PTRSIZE+16)(sp)
  75         PTR_S           a2,16(sp)
  76         PTR_L           a2,(FRAMESZ+16)(sp)
  77         PTR_L           a3,(FRAMESZ+PTRSIZE+16)(sp)
  78 #else
  79         move            a2,a4
  80         move            a3,a5
  81         move            a4,a6
  82 #endif
  83
  84         /* Do the system call */
  85         li              v0,__NR_clone
  86         cfi_endproc
  87         syscall
  88
  89         bnez            a3,L(error)
  90         beqz            v0,L(thread_start)
  91
  92         /* Successful return from the parent */
  93         cfi_startproc
  94         cfi_adjust_cfa_offset (FRAMESZ)
  95         SETUP_GP64_STACK_CFI (GPOFF)
  96         cfi_remember_state
  97         RESTORE_GP64_STACK
  98         PTR_ADDU        sp, FRAMESZ
  99         cfi_adjust_cfa_offset (-FRAMESZ)
 100         ret
 101
 102         /* Something bad happened -- no child created */
 103 L(error):
 104         cfi_restore_state
 105 #ifdef __PIC__
 106         PTR_LA          t9,__syscall_error
 107         RESTORE_GP64_STACK
 108         PTR_ADDU        sp, FRAMESZ
 109         cfi_adjust_cfa_offset (-FRAMESZ)
 110         jr              t9
 111 #else
 112         RESTORE_GP64_STACK
 113         PTR_ADDU        sp, FRAMESZ
 114         cfi_adjust_cfa_offset (-FRAMESZ)
 115         j               __syscall_error
 116 #endif
 117         END(__clone)
 118
 119 /* Load up the arguments to the function.  Put this block of code in
 120    its own function so that we can terminate the stack trace with our
 121    debug info.  */
 122
 123 ENTRY(__thread_start)
 124 L(thread_start):
 125         cfi_undefined ($31)
 126         /* cp is already loaded.  */
 127         SAVE_GP (GPOFF)
 128         /* The stackframe has been created on entry of clone().  */
 129
 130         /* Restore the arg for user's function.  */
 131         PTR_L           t9,0(sp)        /* Function pointer.  */
 132         PTR_L           a0,PTRSIZE(sp)  /* Argument pointer.  */
 133
 134         /* Call the user's function.  */
 135         jal             t9
 136
 137         move            a0,v0
 138         li              v0,__NR_exit
 139         syscall
 140
 141         END(__thread_start)
 142
 143 libc_hidden_def (__clone)
 144 weak_alias (__clone, clone)