1/* Thread-local storage handling in the ELF dynamic linker.
2 AArch64 version.
3 Copyright (C) 2011-2022 Free Software Foundation, Inc.
4
5 This file is part of the GNU C Library.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <https://www.gnu.org/licenses/>. */
20
21#include <sysdep.h>
22#include <tls.h>
23#include "tlsdesc.h"
24
25#define NSAVEDQREGPAIRS 16
26#define SAVE_Q_REGISTERS \
27 stp q0, q1, [sp, #-32*NSAVEDQREGPAIRS]!; \
28 cfi_adjust_cfa_offset (32*NSAVEDQREGPAIRS); \
29 stp q2, q3, [sp, #32*1]; \
30 stp q4, q5, [sp, #32*2]; \
31 stp q6, q7, [sp, #32*3]; \
32 stp q8, q9, [sp, #32*4]; \
33 stp q10, q11, [sp, #32*5]; \
34 stp q12, q13, [sp, #32*6]; \
35 stp q14, q15, [sp, #32*7]; \
36 stp q16, q17, [sp, #32*8]; \
37 stp q18, q19, [sp, #32*9]; \
38 stp q20, q21, [sp, #32*10]; \
39 stp q22, q23, [sp, #32*11]; \
40 stp q24, q25, [sp, #32*12]; \
41 stp q26, q27, [sp, #32*13]; \
42 stp q28, q29, [sp, #32*14]; \
43 stp q30, q31, [sp, #32*15];
44
45#define RESTORE_Q_REGISTERS \
46 ldp q2, q3, [sp, #32*1]; \
47 ldp q4, q5, [sp, #32*2]; \
48 ldp q6, q7, [sp, #32*3]; \
49 ldp q8, q9, [sp, #32*4]; \
50 ldp q10, q11, [sp, #32*5]; \
51 ldp q12, q13, [sp, #32*6]; \
52 ldp q14, q15, [sp, #32*7]; \
53 ldp q16, q17, [sp, #32*8]; \
54 ldp q18, q19, [sp, #32*9]; \
55 ldp q20, q21, [sp, #32*10]; \
56 ldp q22, q23, [sp, #32*11]; \
57 ldp q24, q25, [sp, #32*12]; \
58 ldp q26, q27, [sp, #32*13]; \
59 ldp q28, q29, [sp, #32*14]; \
60 ldp q30, q31, [sp, #32*15]; \
61 ldp q0, q1, [sp], #32*NSAVEDQREGPAIRS; \
62 cfi_adjust_cfa_offset (-32*NSAVEDQREGPAIRS);
63
64 .text
65
66 /* Compute the thread pointer offset for symbols in the static
67 TLS block. The offset is the same for all threads.
68 Prototype:
69 _dl_tlsdesc_return (tlsdesc *) ;
70 */
71 .hidden _dl_tlsdesc_return
72 .global _dl_tlsdesc_return
73 .type _dl_tlsdesc_return,%function
74 cfi_startproc
75 .align 2
76_dl_tlsdesc_return:
77 BTI_C
78 PTR_ARG (0)
79 ldr PTR_REG (0), [x0, #PTR_SIZE]
80 RET
81 cfi_endproc
82 .size _dl_tlsdesc_return, .-_dl_tlsdesc_return
83
84 /* Handler for undefined weak TLS symbols.
85 Prototype:
86 _dl_tlsdesc_undefweak (tlsdesc *);
87
88 The second word of the descriptor contains the addend.
89 Return the addend minus the thread pointer. This ensures
90 that when the caller adds on the thread pointer it gets back
91 the addend. */
92
93 .hidden _dl_tlsdesc_undefweak
94 .global _dl_tlsdesc_undefweak
95 .type _dl_tlsdesc_undefweak,%function
96 cfi_startproc
97 .align 2
98_dl_tlsdesc_undefweak:
99 BTI_C
100 str x1, [sp, #-16]!
101 cfi_adjust_cfa_offset (16)
102 PTR_ARG (0)
103 ldr PTR_REG (0), [x0, #PTR_SIZE]
104 mrs x1, tpidr_el0
105 sub PTR_REG (0), PTR_REG (0), PTR_REG (1)
106 ldr x1, [sp], #16
107 cfi_adjust_cfa_offset (-16)
108 RET
109 cfi_endproc
110 .size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
111
112#ifdef SHARED
113 /* Handler for dynamic TLS symbols.
114 Prototype:
115 _dl_tlsdesc_dynamic (tlsdesc *) ;
116
117 The second word of the descriptor points to a
118 tlsdesc_dynamic_arg structure.
119
120 Returns the offset between the thread pointer and the
121 object referenced by the argument.
122
123 ptrdiff_t
124 __attribute__ ((__regparm__ (1)))
125 _dl_tlsdesc_dynamic (struct tlsdesc *tdp)
126 {
127 struct tlsdesc_dynamic_arg *td = tdp->arg;
128 dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + TCBHEAD_DTV);
129 if (__builtin_expect (td->gen_count <= dtv[0].counter
130 && (dtv[td->tlsinfo.ti_module].pointer.val
131 != TLS_DTV_UNALLOCATED),
132 1))
133 return dtv[td->tlsinfo.ti_module].pointer.val
134 + td->tlsinfo.ti_offset
135 - __thread_pointer;
136
137 return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
138 }
139 */
140
141 .hidden _dl_tlsdesc_dynamic
142 .global _dl_tlsdesc_dynamic
143 .type _dl_tlsdesc_dynamic,%function
144 cfi_startproc
145 .align 2
146_dl_tlsdesc_dynamic:
147 BTI_C
148 PTR_ARG (0)
149
150 /* Save just enough registers to support fast path, if we fall
151 into slow path we will save additional registers. */
152 stp x1, x2, [sp, #-32]!
153 cfi_adjust_cfa_offset (32)
154 stp x3, x4, [sp, #16]
155 cfi_rel_offset (x1, 0)
156 cfi_rel_offset (x2, 8)
157 cfi_rel_offset (x3, 16)
158 cfi_rel_offset (x4, 24)
159
160 mrs x4, tpidr_el0
161 ldr PTR_REG (1), [x0,#TLSDESC_ARG]
162 ldr PTR_REG (0), [x4,#TCBHEAD_DTV]
163 ldr PTR_REG (3), [x1,#TLSDESC_GEN_COUNT]
164 ldr PTR_REG (2), [x0,#DTV_COUNTER]
165 cmp PTR_REG (3), PTR_REG (2)
166 b.hi 2f
167 /* Load r2 = td->tlsinfo.ti_module and r3 = td->tlsinfo.ti_offset. */
168 ldp PTR_REG (2), PTR_REG (3), [x1,#TLSDESC_MODID]
169 add PTR_REG (0), PTR_REG (0), PTR_REG (2), lsl #(PTR_LOG_SIZE + 1)
170 ldr PTR_REG (0), [x0] /* Load val member of DTV entry. */
171 cmp PTR_REG (0), #TLS_DTV_UNALLOCATED
172 b.eq 2f
173 cfi_remember_state
174 sub PTR_REG (3), PTR_REG (3), PTR_REG (4)
175 add PTR_REG (0), PTR_REG (0), PTR_REG (3)
1761:
177 ldp x3, x4, [sp, #16]
178 ldp x1, x2, [sp], #32
179 cfi_adjust_cfa_offset (-32)
180 RET
1812:
182 /* This is the slow path. We need to call __tls_get_addr() which
183 means we need to save and restore all the register that the
184 callee will trash. */
185
186 /* Save the remaining registers that we must treat as caller save. */
187 cfi_restore_state
188# if HAVE_AARCH64_PAC_RET
189 PACIASP
190 cfi_window_save
191# endif
192# define NSAVEXREGPAIRS 8
193 stp x29, x30, [sp,#-16*NSAVEXREGPAIRS]!
194 cfi_adjust_cfa_offset (16*NSAVEXREGPAIRS)
195 cfi_rel_offset (x29, 0)
196 cfi_rel_offset (x30, 8)
197 mov x29, sp
198 stp x5, x6, [sp, #16*1]
199 stp x7, x8, [sp, #16*2]
200 stp x9, x10, [sp, #16*3]
201 stp x11, x12, [sp, #16*4]
202 stp x13, x14, [sp, #16*5]
203 stp x15, x16, [sp, #16*6]
204 stp x17, x18, [sp, #16*7]
205 cfi_rel_offset (x5, 16*1)
206 cfi_rel_offset (x6, 16*1+8)
207 cfi_rel_offset (x7, 16*2)
208 cfi_rel_offset (x8, 16*2+8)
209 cfi_rel_offset (x9, 16*3)
210 cfi_rel_offset (x10, 16*3+8)
211 cfi_rel_offset (x11, 16*4)
212 cfi_rel_offset (x12, 16*4+8)
213 cfi_rel_offset (x13, 16*5)
214 cfi_rel_offset (x14, 16*5+8)
215 cfi_rel_offset (x15, 16*6)
216 cfi_rel_offset (x16, 16*6+8)
217 cfi_rel_offset (x17, 16*7)
218 cfi_rel_offset (x18, 16*7+8)
219
220 SAVE_Q_REGISTERS
221
222 mov x0, x1
223 bl __tls_get_addr
224
225 mrs x1, tpidr_el0
226 sub PTR_REG (0), PTR_REG (0), PTR_REG (1)
227
228 RESTORE_Q_REGISTERS
229
230 ldp x5, x6, [sp, #16*1]
231 ldp x7, x8, [sp, #16*2]
232 ldp x9, x10, [sp, #16*3]
233 ldp x11, x12, [sp, #16*4]
234 ldp x13, x14, [sp, #16*5]
235 ldp x15, x16, [sp, #16*6]
236 ldp x17, x18, [sp, #16*7]
237
238 ldp x29, x30, [sp], #16*NSAVEXREGPAIRS
239 cfi_adjust_cfa_offset (-16*NSAVEXREGPAIRS)
240 cfi_restore (x29)
241 cfi_restore (x30)
242# if HAVE_AARCH64_PAC_RET
243 AUTIASP
244 cfi_window_save
245# endif
246 b 1b
247 cfi_endproc
248 .size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
249# undef NSAVEXREGPAIRS
250#endif
251

source code of glibc/sysdeps/aarch64/dl-tlsdesc.S