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-rw-r--r--libc/sysdeps/linux/x86_64/setcontext.S103
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)