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
182
183
184
185
186
187
188
189
190
|
/* Thread-local storage handling in the ELF dynamic linker. i386 version.
Copyright (C) 2004-2025 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/>. */
#undef REGISTER_SAVE_AREA
#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
# error STATE_SAVE_ALIGNMENT must be multiple of 16
#endif
#if DL_RUNTIME_RESOLVE_REALIGN_STACK
# ifdef USE_FNSAVE
# error USE_FNSAVE shouldn't be defined
# endif
# ifdef USE_FXSAVE
/* Use fxsave to save all registers. */
# define REGISTER_SAVE_AREA 512
# endif
#else
# ifdef USE_FNSAVE
/* Use fnsave to save x87 FPU stack registers. */
# define REGISTER_SAVE_AREA 108
# else
# ifndef USE_FXSAVE
# error USE_FXSAVE must be defined
# endif
/* Use fxsave to save all registers. Add 12 bytes to align the stack
to 16 bytes. */
# define REGISTER_SAVE_AREA (512 + 12)
# endif
#endif
.hidden _dl_tlsdesc_dynamic
.global _dl_tlsdesc_dynamic
.type _dl_tlsdesc_dynamic,@function
/* This function is used for symbols that need dynamic TLS.
%eax points to the TLS descriptor, such that 0(%eax) points to
_dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
tlsdesc_dynamic_arg object. It must return in %eax the offset
between the thread pointer and the object denoted by the
argument, without clobbering any registers.
The assembly code that follows is a rendition of the following
C code, hand-optimized a little bit.
ptrdiff_t
__attribute__ ((__regparm__ (1)))
_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
{
struct tlsdesc_dynamic_arg *td = tdp->arg;
dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
if (__builtin_expect (td->gen_count <= dtv[0].counter
&& (dtv[td->tlsinfo.ti_module].pointer.val
!= TLS_DTV_UNALLOCATED),
1))
return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
- __thread_pointer;
return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
}
*/
cfi_startproc
.align 16
_dl_tlsdesc_dynamic:
/* Like all TLS resolvers, preserve call-clobbered registers.
We need two scratch regs anyway. */
subl $32, %esp
cfi_adjust_cfa_offset (32)
movl %ecx, 20(%esp)
movl %edx, 24(%esp)
movl TLSDESC_ARG(%eax), %eax
movl %gs:DTV_OFFSET, %edx
movl TLSDESC_GEN_COUNT(%eax), %ecx
cmpl (%edx), %ecx
ja 2f
movl TLSDESC_MODID(%eax), %ecx
movl (%edx,%ecx,8), %edx
cmpl $-1, %edx
je 2f
movl TLSDESC_MODOFF(%eax), %eax
addl %edx, %eax
1:
movl 20(%esp), %ecx
subl %gs:0, %eax
movl 24(%esp), %edx
addl $32, %esp
cfi_adjust_cfa_offset (-32)
ret
.p2align 4,,7
2:
cfi_adjust_cfa_offset (32)
#if DL_RUNTIME_RESOLVE_REALIGN_STACK
movl %ebx, -28(%esp)
movl %esp, %ebx
cfi_def_cfa_register(%ebx)
and $-STATE_SAVE_ALIGNMENT, %esp
#endif
#ifdef REGISTER_SAVE_AREA
subl $REGISTER_SAVE_AREA, %esp
# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
# endif
#else
# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
# error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
# endif
/* Allocate stack space of the required size to save the state. */
LOAD_PIC_REG (cx)
subl RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
#endif
#ifdef USE_FNSAVE
fnsave (%esp)
#elif defined USE_FXSAVE
fxsave (%esp)
#else
/* Save the argument for ___tls_get_addr in EAX. */
movl %eax, %ecx
movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
xorl %edx, %edx
/* Clear the XSAVE Header. */
# ifdef USE_XSAVE
movl %edx, (512)(%esp)
movl %edx, (512 + 4 * 1)(%esp)
movl %edx, (512 + 4 * 2)(%esp)
movl %edx, (512 + 4 * 3)(%esp)
# endif
movl %edx, (512 + 4 * 4)(%esp)
movl %edx, (512 + 4 * 5)(%esp)
movl %edx, (512 + 4 * 6)(%esp)
movl %edx, (512 + 4 * 7)(%esp)
movl %edx, (512 + 4 * 8)(%esp)
movl %edx, (512 + 4 * 9)(%esp)
movl %edx, (512 + 4 * 10)(%esp)
movl %edx, (512 + 4 * 11)(%esp)
movl %edx, (512 + 4 * 12)(%esp)
movl %edx, (512 + 4 * 13)(%esp)
movl %edx, (512 + 4 * 14)(%esp)
movl %edx, (512 + 4 * 15)(%esp)
# ifdef USE_XSAVE
xsave (%esp)
# else
xsavec (%esp)
# endif
/* Restore the argument for ___tls_get_addr in EAX. */
movl %ecx, %eax
#endif
call HIDDEN_JUMPTARGET (___tls_get_addr)
/* Get register content back. */
#ifdef USE_FNSAVE
frstor (%esp)
#elif defined USE_FXSAVE
fxrstor (%esp)
#else
/* Save and retore ___tls_get_addr return value stored in EAX. */
movl %eax, %ecx
movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
xorl %edx, %edx
xrstor (%esp)
movl %ecx, %eax
#endif
#if DL_RUNTIME_RESOLVE_REALIGN_STACK
mov %ebx, %esp
cfi_def_cfa_register(%esp)
movl -28(%esp), %ebx
cfi_restore(%ebx)
#else
addl $REGISTER_SAVE_AREA, %esp
cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
#endif
jmp 1b
cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
#undef STATE_SAVE_ALIGNMENT
|
