* If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * Copyright 2010 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. * syscall trap: forksys(2, flags) * syscall trap: forksys(2, 0) * %edx == 0 in parent process, %edx = 1 in child process. * %eax == pid of child in parent, %eax == pid of parent in child. * The child gets a zero return value. * The parent gets the pid of the child. * The child of vfork() will execute in the parent's address space, * thereby changing the stack before the parent runs again. * Therefore we have to be careful how we return from vfork(). * Pity the poor debugger developer who has to deal with this kludge. * We block all blockable signals while performing the vfork() system call * trap. This enables us to set curthread->ul_vfork safely, so that we * don't end up in a signal handler with curthread->ul_vfork set wrong. popq %
r9 /* save return %rip in %r9 */ pushq %
r8 /* save the flags on the stack */ popq %
rsi /* fetch flags from the stack */ /* reconstruct stack before jumping to __cerror */ movq %
rax, %
r9 /* save the vfork() error number */ movq %
r9, %
rax /* restore the vfork() error number */ * To determine if we are (still) a child of vfork(), the child * increments curthread->ul_vfork by one and the parent decrements * it by one. If the result is zero, then we are not a child of * vfork(), else we are. We do this to deal with the case of * a vfork() child calling vfork(). cmpl $0, %
edx /* don't let it go negative */ subl $
1, %
edx /* curthread->ul_vfork--; */ xorl %
eax, %
eax /* zero the return value in the child */ addl $
1, %
edx /* curthread->ul_vfork++; */ * Clear the schedctl interface in both parent and child. * (The child might have modified the parent.) pushq %
rax /* save the vfork() return value */ popq %
rax /* restore the vfork() return value */ jmp *%
r9 /* jump back to the caller */