1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
/* Copyright (C) 2022 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.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file. (The GNU Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)
Note that people who make modified versions of this file are not
obligated to grant this special exception for their modified
versions; it is their choice whether to do so. The GNU Lesser
General Public License gives permission to release a modified
version without this exception; this exception also makes it
possible to release a modified version which carries forward this
exception.
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 <ldsodefs.h>
#include <cheri-rel.h>
/* This is the canonical entry point, usually the first thing in the text
segment.
Note that in case of dynamic linked exe the code in the .init section
has already been run. This includes _init and _libc_init.
At this entry point, most registers' values are unspecified, except:
x0 argc
c1 argv
c2 envp
c3 auxv
c4 Contains a function pointer to be registered with `atexit'.
This is how the dynamic linker arranges to have DT_FINI
functions called for shared libraries that have been loaded
before this code runs. It is unspecified in a static linked
executable.
csp The stack pointer.
*/
asm(""
".global _start\n"
".type _start, %function\n"
"_start:\n"
" .cfi_startproc\n"
" .cfi_undefined c30\n"
" mov c29, czr\n"
" mov c30, czr\n"
" mov c5, csp\n"
" b __real_start\n"
" .cfi_endproc\n"
" .size _start, .-_start\n");
#ifndef SHARED
static int
is_static_linked (void)
{
unsigned long x;
asm (""
".weak __rela_dyn_start\n"
".hidden __rela_dyn_start\n"
"movz %0, #:abs_g3:__rela_dyn_start\n"
"movk %0, #:abs_g2_nc:__rela_dyn_start\n"
"movk %0, #:abs_g1_nc:__rela_dyn_start\n"
"movk %0, #:abs_g0_nc:__rela_dyn_start\n" : "=r"(x));
return x != 0;
}
static uintptr_t
get_rela_dyn_start (void)
{
uintptr_t p;
asm (""
".weak __rela_dyn_start\n"
".hidden __rela_dyn_start\n"
"adrp %0, __rela_dyn_start\n"
"add %0, %0, :lo12:__rela_dyn_start\n" : "=r"(p));
return p;
}
static uintptr_t
get_rela_dyn_end (void)
{
uintptr_t p;
asm (""
".weak __rela_dyn_end\n"
".hidden __rela_dyn_end\n"
"adrp %0, __rela_dyn_end\n"
"add %0, %0, :lo12:__rela_dyn_end\n" : "=r"(p));
return p;
}
static void
get_caps (uintptr_t *cap_rx, uintptr_t *cap_rw, const uintptr_t *auxv)
{
for (;;)
{
switch ((unsigned long)auxv[0])
{
case AT_NULL:
return;
case AT_CHERI_EXEC_RX_CAP:
*cap_rx = auxv[1];
*cap_rx = __builtin_cheri_perms_and (*cap_rx, CAP_PERM_MASK_RX);
break;
case AT_CHERI_EXEC_RW_CAP:
*cap_rw = auxv[1];
*cap_rw = __builtin_cheri_perms_and (*cap_rw, CAP_PERM_MASK_RW);
break;
}
auxv += 2;
}
}
static void
apply_rel (uintptr_t cap_rx, uintptr_t cap_rw, uintptr_t start, uintptr_t end)
{
const ElfW(Rela) *r;
for (r = (const ElfW(Rela) *)start; r != (void *)end; r++)
{
uintptr_t *reloc_addr =
(uintptr_t *) __builtin_cheri_address_set (cap_rw, r->r_offset);
uintptr_t value = morello_relative (0, cap_rx, cap_rw, r, reloc_addr);
*reloc_addr = value;
}
}
#endif /* !SHARED */
int main (int argc, char **argv, char **envp, void *auxv);
void __libc_start_main (int main (int, char **, char **, void *),
int argc, char **argv, char **envp, void *auxv,
void rtld_fini (void), void *sp);
void
__real_start (int argc, char **argv, char **envp, void *auxv,
void (*rtld_fini) (void), uintptr_t *sp)
{
#ifndef SHARED
if (is_static_linked ())
{
uintptr_t start = get_rela_dyn_start ();
uintptr_t end = get_rela_dyn_end ();
uintptr_t cap_rx = 0;
uintptr_t cap_rw = 0;
get_caps (&cap_rx, &cap_rw, auxv);
apply_rel (cap_rx, cap_rw, start, end);
rtld_fini = 0;
}
/* Compiler barrier after relocs are processed. */
asm volatile ("" ::: "memory");
#endif
__libc_start_main (main, argc, argv, envp, auxv, rtld_fini, sp);
__builtin_trap ();
}
int __data_start = 1;
weak_alias (__data_start, data_start);
|
