| /* Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| 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. */ |
| |
| /* clone() is even more special than fork() as it mucks with stacks |
| and invokes a function in the right context after its all over. */ |
| |
| #include <sysdep.h> |
| #define _ERRNO_H 1 |
| #include <bits/errno.h> |
| #include <asm-syntax.h> |
| #include <bp-sym.h> |
| #include <bp-asm.h> |
| |
| #define CLONE_VM 0x00000100 |
| #define CLONE_THREAD 0x00010000 |
| |
| /* The userland implementation is: |
| int clone (int (*fn)(void *arg), void *child_stack, int flags, void *arg), |
| the kernel entry is: |
| int clone (long flags, void *child_stack). |
| |
| The parameters are passed in register and on the stack from userland: |
| rdi: fn |
| rsi: child_stack |
| rdx: flags |
| rcx: arg |
| r8d: TID field in parent |
| r9d: thread pointer |
| %esp+8: TID field in child |
| |
| The kernel expects: |
| rax: system call number |
| rdi: flags |
| rsi: child_stack |
| rdx: TID field in parent |
| r10: TID field in child |
| r8: thread pointer */ |
| |
| |
| .text |
| ENTRY (BP_SYM (__clone)) |
| /* Sanity check arguments. */ |
| movq $-EINVAL,%rax |
| testq %rdi,%rdi /* no NULL function pointers */ |
| jz SYSCALL_ERROR_LABEL |
| testq %rsi,%rsi /* no NULL stack pointers */ |
| jz SYSCALL_ERROR_LABEL |
| |
| /* Insert the argument onto the new stack. */ |
| subq $16,%rsi |
| movq %rcx,8(%rsi) |
| |
| /* Save the function pointer. It will be popped off in the |
| child in the ebx frobbing below. */ |
| movq %rdi,0(%rsi) |
| |
| /* Do the system call. */ |
| movq %rdx, %rdi |
| movq %r8, %rdx |
| movq %r9, %r8 |
| movq 8(%rsp), %r10 |
| movl $SYS_ify(clone),%eax |
| |
| /* End FDE now, because in the child the unwind info will be |
| wrong. */ |
| cfi_endproc; |
| syscall |
| |
| testq %rax,%rax |
| jl SYSCALL_ERROR_LABEL |
| jz L(thread_start) |
| |
| L(pseudo_end): |
| ret |
| |
| L(thread_start): |
| cfi_startproc; |
| /* Clearing frame pointer is insufficient, use CFI. */ |
| cfi_undefined (rip); |
| /* Clear the frame pointer. The ABI suggests this be done, to mark |
| the outermost frame obviously. */ |
| xorl %ebp, %ebp |
| |
| #ifdef RESET_PID |
| testq $CLONE_THREAD, %rdi |
| jne 1f |
| testq $CLONE_VM, %rdi |
| movl $-1, %eax |
| jne 2f |
| movl $SYS_ify(getpid), %eax |
| syscall |
| 2: movl %eax, %fs:PID |
| movl %eax, %fs:TID |
| 1: |
| #endif |
| |
| /* Set up arguments for the function call. */ |
| popq %rax /* Function to call. */ |
| popq %rdi /* Argument. */ |
| call *%rax |
| /* Call exit with return value from function call. */ |
| movq %rax, %rdi |
| call HIDDEN_JUMPTARGET (_exit) |
| cfi_endproc; |
| |
| cfi_startproc; |
| PSEUDO_END (BP_SYM (__clone)) |
| |
| weak_alias (BP_SYM (__clone), BP_SYM (clone)) |
