/* Save current context and install the given one. Copyright (C) 2001-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@redhat.com>, 2001. 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, see <http://www.gnu.org/licenses/>. */ #include <sysdep.h> #include "ucontext_i.h" ENTRY(__swapcontext) /* Load address of the context data structure we save in. */ movl 4(%esp), %eax /* Return value of swapcontext. EAX is the only register whose value is not preserved. */ movl $0, oEAX(%eax) /* Save the 32-bit register values and the return address. */ movl %ecx, oECX(%eax) movl %edx, oEDX(%eax) movl %edi, oEDI(%eax) movl %esi, oESI(%eax) movl %ebp, oEBP(%eax) movl (%esp), %ecx movl %ecx, oEIP(%eax) leal 4(%esp), %ecx movl %ecx, oESP(%eax) movl %ebx, oEBX(%eax) /* Save the FS segment register. */ xorl %edx, %edx movw %fs, %dx movl %edx, oFS(%eax) /* We have separate floating-point register content memory on the stack. We use the __fpregs_mem block in the context. Set the links up correctly. */ leal oFPREGSMEM(%eax), %ecx movl %ecx, oFPREGS(%eax) /* Save the floating-point context. */ fnstenv (%ecx) /* Load address of the context data structure we have to load. */ movl 8(%esp), %ecx /* Save the current signal mask and install the new one. */ pushl %ebx leal oSIGMASK(%eax), %edx leal oSIGMASK(%ecx), %ecx movl $SIG_SETMASK, %ebx movl $__NR_sigprocmask, %eax ENTER_KERNEL popl %ebx cmpl $-4095, %eax /* Check %eax for error. */ jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */ /* EAX was modified, reload it. */ movl 8(%esp), %eax /* Restore the floating-point context. Not the registers, only the rest. */ movl oFPREGS(%eax), %ecx fldenv (%ecx) /* Restore the FS segment register. We don't touch the GS register since it is used for threads. */ movl oFS(%eax), %edx movw %dx, %fs /* Fetch the address to return to. */ movl oEIP(%eax), %ecx /* Load the new stack pointer. */ movl oESP(%eax), %esp /* Push the return address on the new stack so we can return there. */ pushl %ecx /* Load the values of all the 32-bit registers (except ESP). Since we are loading from EAX, it must be last. */ movl oEDI(%eax), %edi movl oESI(%eax), %esi movl oEBP(%eax), %ebp movl oEBX(%eax), %ebx movl oEDX(%eax), %edx movl oECX(%eax), %ecx movl oEAX(%eax), %eax /* The following 'ret' will pop the address of the code and jump to it. */ L(pseudo_end): ret PSEUDO_END(__swapcontext) weak_alias (__swapcontext, swapcontext)