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x86_64: add common trampoline code written in C, port to it

pull/23/head
Ariadne Conill 2020-12-11 23:04:47 -07:00
parent 71cbb6a3d3
commit 2d51d7bfa4
4 changed files with 33 additions and 34 deletions
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28
arch/common/common-trampoline.c Normal file
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@ -0,0 +1,28 @@
/*
* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
*
* 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.
*/
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
void
libucontext_trampoline(void)
{
libucontext_ucontext_t *uc_link;
FETCH_LINKPTR(uc_link);
if (uc_link == NULL)
exit(0);
libucontext_setcontext(uc_link);
}

3
arch/x86_64/defs.h
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@ -31,6 +31,9 @@
#define REG_SZ (8) #define REG_SZ (8)
#define FETCH_LINKPTR(dest) \
asm("movq (%%rbx), %0" : "=rm" ((dest)));
#include "common-defs.h" #include "common-defs.h"
#endif #endif

34
arch/x86_64/startcontext.S
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@ -1,34 +0,0 @@
/*
* Copyright (c) 2018, 2020 Ariadne Conill <ariadne@dereferenced.org>
*
* 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.
*/
#include "defs.h"
FUNC(libucontext_trampoline)
/* get the proper context into position and test for NULL */
movq %rbx, %rsp
movq (%rsp), %rdi
testq %rdi, %rdi
/* if we have no linked context, lets get out of here */
je no_linked_context
/* call setcontext to switch to the linked context */
call libucontext_setcontext@plt
movq %rax, %rdi
no_linked_context:
/* 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
END(libucontext_trampoline)

2
arch/x86_64/trampoline.c Normal file
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#include "defs.h"
#include "common-trampoline.c"