nsz Git - musl/blob - src/env/__init_tls.c

   1 #include <elf.h>
   2 #include <limits.h>
   3 #include <sys/mman.h>
   4 #include <string.h>
   5 #include <stddef.h>
   6 #include "pthread_impl.h"
   7 #include "libc.h"
   8 #include "atomic.h"
   9 #include "syscall.h"
  10
  11 int __init_tp(void *p)
  12 {
  13         pthread_t td = p;
  14         td->self = td;
  15         int r = __set_thread_area(TP_ADJ(p));
  16         if (r < 0) return -1;
  17         if (!r) libc.can_do_threads = 1;
  18         td->detach_state = DT_JOINABLE;
  19         td->tid = __syscall(SYS_set_tid_address, &td->detach_state);
  20         td->locale = &libc.global_locale;
  21         td->robust_list.head = &td->robust_list.head;
  22         return 0;
  23 }
  24
  25 static struct builtin_tls {
  26         char c;
  27         struct pthread pt;
  28         void *space[16];
  29 } builtin_tls[1];
  30 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
  31
  32 static struct tls_module main_tls;
  33
  34 void *__copy_tls(unsigned char *mem)
  35 {
  36         pthread_t td;
  37         struct tls_module *p;
  38         size_t i;
  39         uintptr_t *dtv;
  40
  41 #ifdef TLS_ABOVE_TP
  42         dtv = (uintptr_t*)(mem + libc.tls_size) - (libc.tls_cnt + 1);
  43
  44         mem += -((uintptr_t)mem + sizeof(struct pthread)) & (libc.tls_align-1);
  45         td = (pthread_t)mem;
  46         mem += sizeof(struct pthread);
  47
  48         for (i=1, p=libc.tls_head; p; i++, p=p->next) {
  49                 dtv[i] = (uintptr_t)(mem + p->offset) + DTP_OFFSET;
  50                 memcpy(mem + p->offset, p->image, p->len);
  51         }
  52 #else
  53         dtv = (uintptr_t *)mem;
  54
  55         mem += libc.tls_size - sizeof(struct pthread);
  56         mem -= (uintptr_t)mem & (libc.tls_align-1);
  57         td = (pthread_t)mem;
  58
  59         for (i=1, p=libc.tls_head; p; i++, p=p->next) {
  60                 dtv[i] = (uintptr_t)(mem - p->offset) + DTP_OFFSET;
  61                 memcpy(mem - p->offset, p->image, p->len);
  62         }
  63 #endif
  64         dtv[0] = libc.tls_cnt;
  65         td->dtv = td->dtv_copy = dtv;
  66         return td;
  67 }
  68
  69 #if ULONG_MAX == 0xffffffff
  70 typedef Elf32_Phdr Phdr;
  71 #else
  72 typedef Elf64_Phdr Phdr;
  73 #endif
  74
  75 extern weak hidden const size_t _DYNAMIC[];
  76
  77 static void static_init_tls(size_t *aux)
  78 {
  79         unsigned char *p;
  80         size_t n;
  81         Phdr *phdr, *tls_phdr=0;
  82         size_t base = 0;
  83         void *mem;
  84
  85         for (p=(void *)aux[AT_PHDR],n=aux[AT_PHNUM]; n; n--,p+=aux[AT_PHENT]) {
  86                 phdr = (void *)p;
  87                 if (phdr->p_type == PT_PHDR)
  88                         base = aux[AT_PHDR] - phdr->p_vaddr;
  89                 if (phdr->p_type == PT_DYNAMIC && _DYNAMIC)
  90                         base = (size_t)_DYNAMIC - phdr->p_vaddr;
  91                 if (phdr->p_type == PT_TLS)
  92                         tls_phdr = phdr;
  93                 if (phdr->p_type == PT_GNU_STACK &&
  94                     phdr->p_memsz > __default_stacksize)
  95                         __default_stacksize =
  96                                 phdr->p_memsz < DEFAULT_STACK_MAX ?
  97                                 phdr->p_memsz : DEFAULT_STACK_MAX;
  98         }
  99
 100         if (tls_phdr) {
 101                 main_tls.image = (void *)(base + tls_phdr->p_vaddr);
 102                 main_tls.len = tls_phdr->p_filesz;
 103                 main_tls.size = tls_phdr->p_memsz;
 104                 main_tls.align = tls_phdr->p_align;
 105                 libc.tls_cnt = 1;
 106                 libc.tls_head = &main_tls;
 107         }
 108
 109         main_tls.size += (-main_tls.size - (uintptr_t)main_tls.image)
 110                 & (main_tls.align-1);
 111 #ifdef TLS_ABOVE_TP
 112         main_tls.offset = GAP_ABOVE_TP;
 113         main_tls.offset += -GAP_ABOVE_TP & (main_tls.align-1);
 114 #else
 115         main_tls.offset = main_tls.size;
 116 #endif
 117         if (main_tls.align < MIN_TLS_ALIGN) main_tls.align = MIN_TLS_ALIGN;
 118
 119         libc.tls_align = main_tls.align;
 120         libc.tls_size = 2*sizeof(void *) + sizeof(struct pthread)
 121 #ifdef TLS_ABOVE_TP
 122                 + main_tls.offset
 123 #endif
 124                 + main_tls.size + main_tls.align
 125                 + MIN_TLS_ALIGN-1 & -MIN_TLS_ALIGN;
 126
 127         if (libc.tls_size > sizeof builtin_tls) {
 128 #ifndef SYS_mmap2
 129 #define SYS_mmap2 SYS_mmap
 130 #endif
 131                 mem = (void *)__syscall(
 132                         SYS_mmap2,
 133                         0, libc.tls_size, PROT_READ|PROT_WRITE,
 134                         MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
 135                 /* -4095...-1 cast to void * will crash on dereference anyway,
 136                  * so don't bloat the init code checking for error codes and
 137                  * explicitly calling a_crash(). */
 138         } else {
 139                 mem = builtin_tls;
 140         }
 141
 142         /* Failure to initialize thread pointer is always fatal. */
 143         if (__init_tp(__copy_tls(mem)) < 0)
 144                 a_crash();
 145 }
 146
 147 weak_alias(static_init_tls, __init_tls);