src/env/__init_tls.c

   1 #define SYSCALL_NO_TLS 1
   2 #include <elf.h>
   3 #include <limits.h>
   4 #include <sys/mman.h>
   5 #include <string.h>
   6 #include <stddef.h>
   7 #include "pthread_impl.h"
   8 #include "libc.h"
   9 #include "atomic.h"
  10 #include "syscall.h"
  11
  12 volatile int __thread_list_lock;
  13
  14 int __init_tp(void *p)
  15 {
  16         pthread_t td = p;
  17         td->self = td;
  18         int r = __set_thread_area(TP_ADJ(p));
  19         if (r < 0) return -1;
  20         if (!r) libc.can_do_threads = 1;
  21         td->detach_state = DT_JOINABLE;
  22         td->tid = __syscall(SYS_set_tid_address, &__thread_list_lock);
  23         td->locale = &libc.global_locale;
  24         td->robust_list.head = &td->robust_list.head;
  25         td->sysinfo = __sysinfo;
  26         td->next = td->prev = td;
  27         return 0;
  28 }
  29
  30 static struct builtin_tls {
  31         char c;
  32         struct pthread pt;
  33         void *space[16];
  34 } builtin_tls[1];
  35 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
  36
  37 static struct tls_module main_tls;
  38
  39 void *__copy_tls(unsigned char *mem)
  40 {
  41         pthread_t td;
  42         struct tls_module *p;
  43         size_t i;
  44         uintptr_t *dtv;
  45
  46 #ifdef TLS_ABOVE_TP
  47         dtv = (uintptr_t*)(mem + libc.tls_size) - (libc.tls_cnt + 1);
  48
  49         mem += -((uintptr_t)mem + sizeof(struct pthread)) & (libc.tls_align-1);
  50         td = (pthread_t)mem;
  51         mem += sizeof(struct pthread);
  52
  53         for (i=1, p=libc.tls_head; p; i++, p=p->next) {
  54                 dtv[i] = (uintptr_t)(mem + p->offset) + DTP_OFFSET;
  55                 memcpy(mem + p->offset, p->image, p->len);
  56         }
  57 #else
  58         dtv = (uintptr_t *)mem;
  59
  60         mem += libc.tls_size - sizeof(struct pthread);
  61         mem -= (uintptr_t)mem & (libc.tls_align-1);
  62         td = (pthread_t)mem;
  63
  64         for (i=1, p=libc.tls_head; p; i++, p=p->next) {
  65                 dtv[i] = (uintptr_t)(mem - p->offset) + DTP_OFFSET;
  66                 memcpy(mem - p->offset, p->image, p->len);
  67         }
  68 #endif
  69         dtv[0] = libc.tls_cnt;
  70         td->dtv = td->dtv_copy = dtv;
  71         return td;
  72 }
  73
  74 #if ULONG_MAX == 0xffffffff
  75 typedef Elf32_Phdr Phdr;
  76 #else
  77 typedef Elf64_Phdr Phdr;
  78 #endif
  79
  80 extern weak hidden const size_t _DYNAMIC[];
  81
  82 static void static_init_tls(size_t *aux)
  83 {
  84         unsigned char *p;
  85         size_t n;
  86         Phdr *phdr, *tls_phdr=0;
  87         size_t base = 0;
  88         void *mem;
  89
  90         for (p=(void *)aux[AT_PHDR],n=aux[AT_PHNUM]; n; n--,p+=aux[AT_PHENT]) {
  91                 phdr = (void *)p;
  92                 if (phdr->p_type == PT_PHDR)
  93                         base = aux[AT_PHDR] - phdr->p_vaddr;
  94                 if (phdr->p_type == PT_DYNAMIC && _DYNAMIC)
  95                         base = (size_t)_DYNAMIC - phdr->p_vaddr;
  96                 if (phdr->p_type == PT_TLS)
  97                         tls_phdr = phdr;
  98                 if (phdr->p_type == PT_GNU_STACK &&
  99                     phdr->p_memsz > __default_stacksize)
 100                         __default_stacksize =
 101                                 phdr->p_memsz < DEFAULT_STACK_MAX ?
 102                                 phdr->p_memsz : DEFAULT_STACK_MAX;
 103         }
 104
 105         if (tls_phdr) {
 106                 main_tls.image = (void *)(base + tls_phdr->p_vaddr);
 107                 main_tls.len = tls_phdr->p_filesz;
 108                 main_tls.size = tls_phdr->p_memsz;
 109                 main_tls.align = tls_phdr->p_align;
 110                 libc.tls_cnt = 1;
 111                 libc.tls_head = &main_tls;
 112         }
 113
 114         main_tls.size += (-main_tls.size - (uintptr_t)main_tls.image)
 115                 & (main_tls.align-1);
 116 #ifdef TLS_ABOVE_TP
 117         main_tls.offset = GAP_ABOVE_TP;
 118         main_tls.offset += (-GAP_ABOVE_TP + (uintptr_t)main_tls.image)
 119                 & (main_tls.align-1);
 120 #else
 121         main_tls.offset = main_tls.size;
 122 #endif
 123         if (main_tls.align < MIN_TLS_ALIGN) main_tls.align = MIN_TLS_ALIGN;
 124
 125         libc.tls_align = main_tls.align;
 126         libc.tls_size = 2*sizeof(void *) + sizeof(struct pthread)
 127 #ifdef TLS_ABOVE_TP
 128                 + main_tls.offset
 129 #endif
 130                 + main_tls.size + main_tls.align
 131                 + MIN_TLS_ALIGN-1 & -MIN_TLS_ALIGN;
 132
 133         if (libc.tls_size > sizeof builtin_tls) {
 134 #ifndef SYS_mmap2
 135 #define SYS_mmap2 SYS_mmap
 136 #endif
 137                 mem = (void *)__syscall(
 138                         SYS_mmap2,
 139                         0, libc.tls_size, PROT_READ|PROT_WRITE,
 140                         MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
 141                 /* -4095...-1 cast to void * will crash on dereference anyway,
 142                  * so don't bloat the init code checking for error codes and
 143                  * explicitly calling a_crash(). */
 144         } else {
 145                 mem = builtin_tls;
 146         }
 147
 148         /* Failure to initialize thread pointer is always fatal. */
 149         if (__init_tp(__copy_tls(mem)) < 0)
 150                 a_crash();
 151 }
 152
 153 weak_alias(static_init_tls, __init_tls);