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
|
/* longjmp for i386.
Copyright (C) 1995-2021 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 <jmpbuf-offsets.h>
#include <jmp_buf-ssp.h>
#include <asm-syntax.h>
#include <stap-probe.h>
/* Don't restore shadow stack register if
1. Shadow stack isn't enabled. Or
2. __longjmp is defined for __longjmp_cancel.
*/
#if !SHSTK_ENABLED || defined __longjmp
# undef SHADOW_STACK_POINTER_OFFSET
#endif
.text
ENTRY (__longjmp)
#ifdef PTR_DEMANGLE
movl 4(%esp), %eax /* User's jmp_buf in %eax. */
# ifdef SHADOW_STACK_POINTER_OFFSET
# if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET
/* Check if Shadow Stack is enabled. */
testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET
jz L(skip_ssp)
# else
xorl %edx, %edx
# endif
/* Check and adjust the Shadow-Stack-Pointer. */
rdsspd %edx
/* And compare it with the saved ssp value. */
subl SHADOW_STACK_POINTER_OFFSET(%eax), %edx
je L(skip_ssp)
/* Count the number of frames to adjust and adjust it
with incssp instruction. The instruction can adjust
the ssp by [0..255] value only thus use a loop if
the number of frames is bigger than 255. */
negl %edx
shrl $2, %edx
/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
restoring Shadow-Stack-Pointer of setjmp's caller, we
need to unwind shadow stack by one more frame. */
addl $1, %edx
movl $255, %ebx
L(loop):
cmpl %ebx, %edx
cmovb %edx, %ebx
incsspd %ebx
subl %ebx, %edx
ja L(loop)
L(skip_ssp):
# endif
/* Save the return address now. */
movl (JB_PC*4)(%eax), %edx
/* Get the stack pointer. */
movl (JB_SP*4)(%eax), %ecx
PTR_DEMANGLE (%edx)
PTR_DEMANGLE (%ecx)
LIBC_PROBE (longjmp, 3, 4@%eax, -4@8(%esp), 4@%edx)
cfi_def_cfa(%eax, 0)
cfi_register(%eip, %edx)
cfi_register(%esp, %ecx)
cfi_offset(%ebx, JB_BX*4)
cfi_offset(%esi, JB_SI*4)
cfi_offset(%edi, JB_DI*4)
cfi_offset(%ebp, JB_BP*4)
/* Restore registers. */
movl (JB_BX*4)(%eax), %ebx
movl (JB_SI*4)(%eax), %esi
movl (JB_DI*4)(%eax), %edi
movl (JB_BP*4)(%eax), %ebp
cfi_restore(%ebx)
cfi_restore(%esi)
cfi_restore(%edi)
cfi_restore(%ebp)
LIBC_PROBE (longjmp_target, 3, 4@%eax, -4@8(%esp), 4@%edx)
movl 8(%esp), %eax /* Second argument is return value. */
movl %ecx, %esp
#else
movl 4(%esp), %ecx /* User's jmp_buf in %ecx. */
movl 8(%esp), %eax /* Second argument is return value. */
# ifdef SHADOW_STACK_POINTER_OFFSET
# if IS_IN (libc) && defined SHARED
/* Check if Shadow Stack is enabled. */
testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET
jz L(skip_ssp)
# endif
/* Check and adjust the Shadow-Stack-Pointer. */
xorl %edx, %edx
/* Get the current ssp. */
rdsspd %edx
/* And compare it with the saved ssp value. */
subl SHADOW_STACK_POINTER_OFFSET(%ecx), %edx
je L(skip_ssp)
/* Count the number of frames to adjust and adjust it
with incssp instruction. The instruction can adjust
the ssp by [0..255] value only thus use a loop if
the number of frames is bigger than 255. */
negl %edx
shrl $2, %edx
/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
restoring Shadow-Stack-Pointer of setjmp's caller, we
need to unwind shadow stack by one more frame. */
addl $1, %edx
movl $255, %ebx
L(loop):
cmpl %ebx, %edx
cmovb %edx, %ebx
incsspd %ebx
subl %ebx, %edx
ja L(loop)
L(skip_ssp):
# endif
/* Save the return address now. */
movl (JB_PC*4)(%ecx), %edx
LIBC_PROBE (longjmp, 3, 4@%ecx, -4@%eax, 4@%edx)
/* Restore registers. */
movl (JB_BX*4)(%ecx), %ebx
movl (JB_SI*4)(%ecx), %esi
movl (JB_DI*4)(%ecx), %edi
movl (JB_BP*4)(%ecx), %ebp
movl (JB_SP*4)(%ecx), %esp
LIBC_PROBE (longjmp_target, 3, 4@%ecx, -4@%ecx, 4@%edx)
#endif
/* Jump to saved PC. */
jmp *%edx
END (__longjmp)
|
