diff options
Diffstat (limited to 'libc/sysdeps/linux/x86_64/setcontext.S')
| -rw-r--r-- | libc/sysdeps/linux/x86_64/setcontext.S | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/x86_64/setcontext.S b/libc/sysdeps/linux/x86_64/setcontext.S new file mode 100644 index 000000000..561ab9f75 --- /dev/null +++ b/libc/sysdeps/linux/x86_64/setcontext.S @@ -0,0 +1,103 @@ +/* Install given context. + 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 __setcontext (const ucontext_t *ucp) + + 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 restore anything + other than the PRESERVED state. */ + +ENTRY(__setcontext) + /* Save argument since syscall will destroy it. */ + pushq %rdi + cfi_adjust_cfa_offset(8) + + /* Set the signal mask with + rt_sigprocmask (SIG_SETMASK, mask, NULL, _NSIG/8). */ + leaq oSIGMASK(%rdi), %rsi + xorl %edx, %edx + movl $SIG_SETMASK, %edi + movl $_NSIG8,%r10d + movl $__NR_rt_sigprocmask, %eax + syscall + popq %rdi /* Reload %rdi, adjust stack. */ + cfi_adjust_cfa_offset(-8) + cmpq $-4095, %rax /* Check %rax for error. */ + jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */ + + /* Restore the floating-point context. Not the registers, only the + rest. */ + movq oFPREGS(%rdi), %rcx + fldenv (%rcx) + ldmxcsr oMXCSR(%rdi) + + + /* Load the new stack pointer, the preserved registers and + registers used for passing args. */ + cfi_def_cfa(%rdi, 0) + cfi_offset(%rbx,oRBX) + cfi_offset(%rbp,oRBP) + cfi_offset(%r12,oR12) + cfi_offset(%r13,oR13) + cfi_offset(%r14,oR14) + cfi_offset(%r15,oR15) + cfi_offset(%rsp,oRSP) + cfi_offset(%rip,oRIP) + + movq oRSP(%rdi), %rsp + movq oRBX(%rdi), %rbx + movq oRBP(%rdi), %rbp + movq oR12(%rdi), %r12 + movq oR13(%rdi), %r13 + movq oR14(%rdi), %r14 + movq oR15(%rdi), %r15 + + /* The following ret should return to the address set with + getcontext. Therefore push the address on the stack. */ + movq oRIP(%rdi), %rcx + pushq %rcx + + movq oRSI(%rdi), %rsi + movq oRDX(%rdi), %rdx + movq oRCX(%rdi), %rcx + movq oR8(%rdi), %r8 + movq oR9(%rdi), %r9 + + /* Setup finally %rdi. */ + movq oRDI(%rdi), %rdi + + /* End FDE here, we fall into another context. */ + cfi_endproc + cfi_startproc + + /* Clear rax to indicate success. */ + xorl %eax, %eax +L(pseudo_end): + ret +PSEUDO_END(__setcontext) + +weak_alias (__setcontext, setcontext) |