libucontext/arch/x86/startcontext.S

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/*
* Copyright (c) 2018 Ariadne Conill <ariadne@dereferenced.org>
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*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
.globl __start_context;
__start_context:
/* get the proper context into position and test for NULL */
leal (%esp,%ebx,4), %esp
cmpl $0, (%esp)
/* restore global offset table, exit@plt and __setcontext@plt need this */
call __i686.get_pc_thunk.bx
addl $_GLOBAL_OFFSET_TABLE_, %ebx
/* if we have no linked context, lets get out of here */
je no_linked_context
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/* call setcontext to switch to the linked context */
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call __setcontext@plt
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movl %eax, (%esp)
no_linked_context:
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/* we are returning into a null context, it seems, so maybe we should exit */
call exit@plt
/* something is really hosed, call hlt to force termination */
hlt
__i686.get_pc_thunk.bx:
mov (%esp), %ebx
ret