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Diffstat (limited to 'libc/sysdeps/linux/i386/swapcontext.S')
-rw-r--r--libc/sysdeps/linux/i386/swapcontext.S110
1 files changed, 110 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/i386/swapcontext.S b/libc/sysdeps/linux/i386/swapcontext.S
new file mode 100644
index 000000000..ee5d0e4d5
--- /dev/null
+++ b/libc/sysdeps/linux/i386/swapcontext.S
@@ -0,0 +1,110 @@
+/* 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)