1 | #include <elf.h>
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2 | #include <limits.h>
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3 | #include <sys/mman.h>
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4 | #include <string.h>
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5 | #include <stddef.h>
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6 | #include "pthread_impl.h"
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7 | #include "libc.h"
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8 | #include "atomic.h"
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9 | #include "syscall.h"
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10 |
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11 | int __init_tp(void *p)
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12 | {
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13 | pthread_t td = p;
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14 | td->self = td;
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15 | int r = __set_thread_area(TP_ADJ(p));
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16 | if (r < 0) return -1;
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17 | if (!r) libc.can_do_threads = 1;
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18 | td->tid = __syscall(SYS_set_tid_address, &td->tid);
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19 | td->locale = &libc.global_locale;
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20 | td->robust_list.head = &td->robust_list.head;
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21 | return 0;
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22 | }
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23 |
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24 | static struct builtin_tls {
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25 | char c;
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26 | struct pthread pt;
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27 | void *space[16];
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28 | } builtin_tls[1];
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29 | #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
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30 |
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31 | static struct tls_module main_tls;
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32 |
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33 | void *__copy_tls(unsigned char *mem)
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34 | {
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35 | pthread_t td;
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36 | struct tls_module *p;
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37 | size_t i;
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38 | void **dtv;
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39 |
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40 | #ifdef TLS_ABOVE_TP
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41 | dtv = (void **)(mem + libc.tls_size) - (libc.tls_cnt + 1);
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42 |
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43 | mem += -((uintptr_t)mem + sizeof(struct pthread)) & (libc.tls_align-1);
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44 | td = (pthread_t)mem;
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45 | mem += sizeof(struct pthread);
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46 |
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47 | for (i=1, p=libc.tls_head; p; i++, p=p->next) {
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48 | dtv[i] = mem + p->offset;
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49 | memcpy(dtv[i], p->image, p->len);
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50 | }
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51 | #else
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52 | dtv = (void **)mem;
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53 |
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54 | mem += libc.tls_size - sizeof(struct pthread);
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55 | mem -= (uintptr_t)mem & (libc.tls_align-1);
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56 | td = (pthread_t)mem;
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57 |
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58 | for (i=1, p=libc.tls_head; p; i++, p=p->next) {
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59 | dtv[i] = mem - p->offset;
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60 | memcpy(dtv[i], p->image, p->len);
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61 | }
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62 | #endif
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63 | dtv[0] = (void *)libc.tls_cnt;
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64 | td->dtv = td->dtv_copy = dtv;
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65 | return td;
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66 | }
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67 |
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68 | #if ULONG_MAX == 0xffffffff
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69 | typedef Elf32_Phdr Phdr;
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70 | #else
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71 | typedef Elf64_Phdr Phdr;
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72 | #endif
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73 |
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74 | __attribute__((__weak__, __visibility__("hidden")))
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75 | extern const size_t _DYNAMIC[];
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76 |
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77 | static void static_init_tls(size_t *aux)
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78 | {
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79 | unsigned char *p;
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80 | size_t n;
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81 | Phdr *phdr, *tls_phdr=0;
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82 | size_t base = 0;
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83 | void *mem;
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84 |
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85 | for (p=(void *)aux[AT_PHDR],n=aux[AT_PHNUM]; n; n--,p+=aux[AT_PHENT]) {
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86 | phdr = (void *)p;
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87 | if (phdr->p_type == PT_PHDR)
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88 | base = aux[AT_PHDR] - phdr->p_vaddr;
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89 | if (phdr->p_type == PT_DYNAMIC && _DYNAMIC)
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90 | base = (size_t)_DYNAMIC - phdr->p_vaddr;
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91 | if (phdr->p_type == PT_TLS)
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92 | tls_phdr = phdr;
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93 | }
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94 |
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95 | if (tls_phdr) {
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96 | main_tls.image = (void *)(base + tls_phdr->p_vaddr);
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97 | main_tls.len = tls_phdr->p_filesz;
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98 | main_tls.size = tls_phdr->p_memsz;
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99 | main_tls.align = tls_phdr->p_align;
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100 | libc.tls_cnt = 1;
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101 | libc.tls_head = &main_tls;
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102 | }
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103 |
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104 | main_tls.size += (-main_tls.size - (uintptr_t)main_tls.image)
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105 | & (main_tls.align-1);
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106 | if (main_tls.align < MIN_TLS_ALIGN) main_tls.align = MIN_TLS_ALIGN;
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107 | #ifndef TLS_ABOVE_TP
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108 | main_tls.offset = main_tls.size;
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109 | #endif
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110 |
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111 | libc.tls_align = main_tls.align;
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112 | libc.tls_size = 2*sizeof(void *) + sizeof(struct pthread)
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113 | + main_tls.size + main_tls.align
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114 | + MIN_TLS_ALIGN-1 & -MIN_TLS_ALIGN;
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115 |
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116 | if (libc.tls_size > sizeof builtin_tls) {
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117 | #ifndef SYS_mmap2
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118 | #define SYS_mmap2 SYS_mmap
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119 | #endif
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120 | mem = (void *)__syscall(
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121 | SYS_mmap2,
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122 | 0, libc.tls_size, PROT_READ|PROT_WRITE,
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123 | MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
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124 | /* -4095...-1 cast to void * will crash on dereference anyway,
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125 | * so don't bloat the init code checking for error codes and
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126 | * explicitly calling a_crash(). */
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127 | } else {
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128 | mem = builtin_tls;
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129 | }
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130 |
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131 | /* Failure to initialize thread pointer is always fatal. */
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132 | if (__init_tp(__copy_tls(mem)) < 0)
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133 | a_crash();
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134 | }
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135 |
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136 | weak_alias(static_init_tls, __init_tls);
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