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121 lines
3.7 KiB
ArmAsm
121 lines
3.7 KiB
ArmAsm
/* Create new context.
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Copyright (C) 2001-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include "ucontext_i.h"
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ENTRY(__makecontext)
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movl 4(%esp), %eax
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/* Load the address of the function we are supposed to run. */
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movl 8(%esp), %ecx
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/* Compute the address of the stack. The information comes from
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to us_stack element. */
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movl oSS_SP(%eax), %edx
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movl %ecx, oEIP(%eax)
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addl oSS_SIZE(%eax), %edx
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/* Remember the number of parameters for the exit handler since
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it has to remove them. We store the number in the EBX register
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which the function we will call must preserve. */
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movl 12(%esp), %ecx
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movl %ecx, oEBX(%eax)
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/* Make room on the new stack for the parameters.
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Room for the arguments, return address (== L(exitcode)) and
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oLINK pointer is needed. One of the pointer sizes is subtracted
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after aligning the stack. */
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negl %ecx
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leal -4(%edx,%ecx,4), %edx
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negl %ecx
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/* Align the stack. */
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andl $0xfffffff0, %edx
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subl $4, %edx
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/* Store the future stack pointer. */
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movl %edx, oESP(%eax)
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/* Put the next context on the new stack (from the uc_link
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element). */
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movl oLINK(%eax), %eax
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movl %eax, 4(%edx,%ecx,4)
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/* Copy all the parameters. */
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jecxz 2f
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1: movl 12(%esp,%ecx,4), %eax
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movl %eax, (%edx,%ecx,4)
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decl %ecx
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jnz 1b
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2:
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/* If the function we call returns we must continue with the
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context which is given in the uc_link element. To do this
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set the return address for the function the user provides
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to a little bit of helper code which does the magic (see
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below). */
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#ifdef PIC
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call 1f
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cfi_adjust_cfa_offset (4)
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1: popl %ecx
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cfi_adjust_cfa_offset (-4)
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addl $L(exitcode)-1b, %ecx
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movl %ecx, (%edx)
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#else
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movl $L(exitcode), (%edx)
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#endif
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/* We need to terminate the FDE here instead of after ret because
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the unwinder looks at ra-1 for unwind information. */
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cfi_endproc
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/* 'makecontext' returns no value. */
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ret
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/* This is the helper code which gets called if a function which
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is registered with 'makecontext' returns. In this case we
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have to install the context listed in the uc_link element of
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the context 'makecontext' manipulated at the time of the
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'makecontext' call. If the pointer is NULL the process must
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terminate. */
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L(exitcode):
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/* This removes the parameters passed to the function given to
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'makecontext' from the stack. EBX contains the number of
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parameters (see above). */
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leal (%esp,%ebx,4), %esp
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cmpl $0, (%esp) /* Check the next context. */
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je 2f /* If it is zero exit. */
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call HIDDEN_JUMPTARGET(__setcontext)
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/* If this returns (which can happen if the syscall fails) we'll
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exit the program with the return error value (-1). */
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movl %eax, (%esp)
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2: call HIDDEN_JUMPTARGET(exit)
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/* The 'exit' call should never return. In case it does cause
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the process to terminate. */
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hlt
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cfi_startproc
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END(__makecontext)
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weak_alias (__makecontext, makecontext)
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