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/* Save current context and install the given one.
Copyright (C) 2001-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://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)
leal oFPREGS(%eax), %ecx
/* 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. */
subl $12, %esp
cfi_adjust_cfa_offset (12)
leal oSIGMASK(%eax), %eax
movl %eax, 8(%esp)
leal oSIGMASK(%ecx), %eax
movl %eax, 4(%esp)
movl $SIG_SETMASK, (%esp)
call HIDDEN_JUMPTARGET (__sigprocmask)
addl $12, %esp
cfi_adjust_cfa_offset (-12)
testl %eax, %eax
jne L(pseudo_end)
/* EAX was modified, reload it. */
movl 8(%esp), %eax
/* Restore the floating-point context. Not the registers, only the
rest. */
leal 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)
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