/* Save current context and install the given one. Copyright (C) 2002-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Andreas Jaeger <aj@suse.de>, 2002. 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" /* int __swapcontext (ucontext_t *oucp, const ucontext_t *ucp); Saves the machine context in oucp such that when it is activated, it appears as if __swapcontextt() returned again, restores the machine context in ucp and thereby resumes execution in that context. This implementation is intended to be used for *synchronous* context switches only. Therefore, it does not have to save anything other than the PRESERVED state. */ ENTRY(__swapcontext) /* Save the preserved registers, the registers used for passing args, and the return address. */ movq %rbx, oRBX(%rdi) movq %rbp, oRBP(%rdi) movq %r12, oR12(%rdi) movq %r13, oR13(%rdi) movq %r14, oR14(%rdi) movq %r15, oR15(%rdi) movq %rdi, oRDI(%rdi) movq %rsi, oRSI(%rdi) movq %rdx, oRDX(%rdi) movq %rcx, oRCX(%rdi) movq %r8, oR8(%rdi) movq %r9, oR9(%rdi) movq (%rsp), %rcx movq %rcx, oRIP(%rdi) leaq 8(%rsp), %rcx /* Exclude the return address. */ movq %rcx, oRSP(%rdi) /* 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. */ leaq oFPREGSMEM(%rdi), %rcx movq %rcx, oFPREGS(%rdi) /* Save the floating-point environment. */ fnstenv (%rcx) stmxcsr oMXCSR(%rdi) /* The syscall destroys some registers, save them. */ movq %rsi, %r12 /* Save the current signal mask and install the new one with rt_sigprocmask (SIG_BLOCK, newset, oldset,_NSIG/8). */ leaq oSIGMASK(%rdi), %rdx leaq oSIGMASK(%rsi), %rsi movl $SIG_SETMASK, %edi movl $_NSIG8,%r10d movl $__NR_rt_sigprocmask, %eax syscall cmpq $-4095, %rax /* Check %rax for error. */ jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */ /* Restore destroyed registers. */ movq %r12, %rsi /* Restore the floating-point context. Not the registers, only the rest. */ movq oFPREGS(%rsi), %rcx fldenv (%rcx) ldmxcsr oMXCSR(%rsi) /* Load the new stack pointer and the preserved registers. */ movq oRSP(%rsi), %rsp movq oRBX(%rsi), %rbx movq oRBP(%rsi), %rbp movq oR12(%rsi), %r12 movq oR13(%rsi), %r13 movq oR14(%rsi), %r14 movq oR15(%rsi), %r15 /* The following ret should return to the address set with getcontext. Therefore push the address on the stack. */ movq oRIP(%rsi), %rcx pushq %rcx /* Setup registers used for passing args. */ movq oRDI(%rsi), %rdi movq oRDX(%rsi), %rdx movq oRCX(%rsi), %rcx movq oR8(%rsi), %r8 movq oR9(%rsi), %r9 /* Setup finally %rsi. */ movq oRSI(%rsi), %rsi /* Clear rax to indicate success. */ xorl %eax, %eax L(pseudo_end): ret PSEUDO_END(__swapcontext) weak_alias (__swapcontext, swapcontext)