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- /* Initialization code for TLS in statically linked application.
- Copyright (C) 2002, 2003, 2004, 2005 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
- <http://www.gnu.org/licenses/>. */
- #include <errno.h>
- #include <ldsodefs.h>
- #include <tls.h>
- #include <unistd.h>
- #include <stdio.h>
- #include <sys/param.h>
- #include <elf.h>
- #include <link.h>
- #include <string.h>
- #include <stdlib.h>
- #include <sys/mman.h>
- #ifdef SHARED
- #error makefile bug, this file is for static only
- #endif
- #if USE_TLS
- extern ElfW(Phdr) *_dl_phdr;
- extern size_t _dl_phnum;
- #ifdef __FDPIC__
- /* phdr->p_vaddr is not valid in FDPIC mode. To find tdata start we
- use the linker script defined symbol __tdata_start. */
- extern int __tdata_start;
- #endif
- #ifdef SHARED
- static
- #endif
- dtv_t static_dtv[2 + TLS_SLOTINFO_SURPLUS];
- static struct
- {
- struct dtv_slotinfo_list si;
- /* The dtv_slotinfo_list data structure does not include the actual
- information since it is defined as an array of size zero. We define
- here the necessary entries. Note that it is not important whether
- there is padding or not since we will always access the information
- through the 'si' element. */
- struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS];
- } static_slotinfo;
- /* Fake link map for the application. */
- static struct link_map static_map;
- /* Highest dtv index currently needed. */
- size_t _dl_tls_max_dtv_idx;
- /* Flag signalling whether there are gaps in the module ID allocation. */
- bool _dl_tls_dtv_gaps;
- /* Information about the dtv slots. */
- struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;
- /* Number of modules in the static TLS block. */
- size_t _dl_tls_static_nelem;
- /* Size of the static TLS block. */
- size_t _dl_tls_static_size;
- /* Size actually allocated in the static TLS block. */
- size_t _dl_tls_static_used;
- /* Alignment requirement of the static TLS block. */
- size_t _dl_tls_static_align;
- /* Generation counter for the dtv. */
- size_t _dl_tls_generation;
- /* Additional definitions needed by TLS initialization. */
- #ifdef TLS_INIT_HELPER
- TLS_INIT_HELPER
- #endif
- static inline void
- init_slotinfo (void)
- {
- /* Create the slotinfo list. */
- static_slotinfo.si.len = (((char *) (&static_slotinfo + 1)
- - (char *) &static_slotinfo.si.slotinfo[0])
- / sizeof static_slotinfo.si.slotinfo[0]);
- // static_slotinfo.si.next = NULL; already zero
- /* The slotinfo list. Will be extended by the code doing dynamic
- linking. */
- GL(dl_tls_max_dtv_idx) = 1;
- GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si;
- }
- static inline void
- init_static_tls (size_t memsz, size_t align)
- {
- /* That is the size of the TLS memory for this object. The initialized
- value of _dl_tls_static_size is provided by dl-open.c to request some
- surplus that permits dynamic loading of modules with IE-model TLS. */
- GL(dl_tls_static_size) = roundup (memsz + GL(dl_tls_static_size),
- TLS_TCB_ALIGN);
- GL(dl_tls_static_used) = memsz;
- /* The alignment requirement for the static TLS block. */
- GL(dl_tls_static_align) = align;
- /* Number of elements in the static TLS block. */
- GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx);
- }
- void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
- void
- __libc_setup_tls (size_t tcbsize, size_t tcbalign)
- {
- void *tlsblock;
- size_t memsz = 0;
- size_t filesz = 0;
- void *initimage = NULL;
- size_t align = 0;
- size_t max_align = tcbalign;
- size_t tcb_offset;
- ElfW(Phdr) *phdr;
- /* Look through the TLS segment if there is any. */
- if (_dl_phdr != NULL)
- for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)
- if (phdr->p_type == PT_TLS)
- {
- /* Remember the values we need. */
- memsz = phdr->p_memsz;
- filesz = phdr->p_filesz;
- #ifdef __FDPIC__
- initimage = (void *) &__tdata_start;
- #else
- initimage = (void *) phdr->p_vaddr;
- #endif
- align = phdr->p_align;
- if (phdr->p_align > max_align)
- max_align = phdr->p_align;
- break;
- }
- /* We have to set up the TCB block which also (possibly) contains
- 'errno'. Therefore we avoid 'malloc' which might touch 'errno'.
- Instead we use 'sbrk' which would only uses 'errno' if it fails.
- In this case we are right away out of memory and the user gets
- what she/he deserves.
- The initialized value of _dl_tls_static_size is provided by dl-open.c
- to request some surplus that permits dynamic loading of modules with
- IE-model TLS. */
- /* Use mmap instead of sbrk since this commit disables sbrk area
- for FDPIC MMU-less platforms:
- fs/binfmt_elf_fdpic.c: fix brk area overlap with stack on NOMMU
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/fs/binfmt_elf_fdpic.c?id=4ac313111018cb44ecc250445de5ccb93026a980
- */
- # if defined(TLS_TCB_AT_TP)
- tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign);
- # if defined(__FDPIC__)
- tlsblock = mmap (NULL, tcb_offset + tcbsize + max_align,
- PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- # else
- tlsblock = sbrk (tcb_offset + tcbsize + max_align);
- # endif
- # elif defined(TLS_DTV_AT_TP)
- tcb_offset = roundup (tcbsize, align ?: 1);
- # if defined(__FDPIC__)
- tlsblock = mmap (NULL, tcb_offset + memsz + max_align + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size),
- PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- # else
- tlsblock = sbrk (tcb_offset + memsz + max_align
- + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
- # endif
- memset(tlsblock, '\0', tcb_offset + memsz + max_align + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
- tlsblock += TLS_PRE_TCB_SIZE;
- # else
- /* In case a model with a different layout for the TCB and DTV
- is defined add another #elif here and in the following #ifs. */
- # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
- # endif
- /* Align the TLS block. */
- tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
- & ~(max_align - 1));
- /* Initialize the dtv. [0] is the length, [1] the generation counter. */
- static_dtv[0].counter = (sizeof (static_dtv) / sizeof (static_dtv[0])) - 2;
- // static_dtv[1].counter = 0; would be needed if not already done
- /* Initialize the TLS block. */
- # if defined(TLS_TCB_AT_TP)
- static_dtv[2].pointer.val = ((char *) tlsblock + tcb_offset
- - roundup (memsz, align ?: 1));
- static_map.l_tls_offset = roundup (memsz, align ?: 1);
- # elif defined(TLS_DTV_AT_TP)
- static_dtv[2].pointer.val = (char *) tlsblock + tcb_offset;
- static_map.l_tls_offset = tcb_offset;
- # else
- # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
- # endif
- static_dtv[2].pointer.is_static = true;
- /* sbrk gives us zero'd memory, so we don't need to clear the remainder. */
- memcpy (static_dtv[2].pointer.val, initimage, filesz);
- /* Install the pointer to the dtv. */
- /* Initialize the thread pointer. */
- # if defined(TLS_TCB_AT_TP)
- INSTALL_DTV ((char *) tlsblock + tcb_offset, static_dtv);
- const char *lossage = TLS_INIT_TP ((char *) tlsblock + tcb_offset, 0);
- # elif defined(TLS_DTV_AT_TP)
- INSTALL_DTV (tlsblock, static_dtv);
- const char *lossage = (char *)TLS_INIT_TP (tlsblock, 0);
- # else
- # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
- # endif
- if (__builtin_expect (lossage != NULL, 0))
- abort();
- /* We have to create a fake link map which normally would be created
- by the dynamic linker. It just has to have enough information to
- make the TLS routines happy. */
- static_map.l_tls_align = align;
- static_map.l_tls_blocksize = memsz;
- static_map.l_tls_initimage = initimage;
- static_map.l_tls_initimage_size = filesz;
- static_map.l_tls_modid = 1;
- init_slotinfo ();
- // static_slotinfo.si.slotinfo[1].gen = 0; already zero
- static_slotinfo.si.slotinfo[1].map = &static_map;
- memsz = roundup (memsz, align ?: 1);
- # if defined(TLS_TCB_AT_TP)
- memsz += tcbsize;
- # elif defined(TLS_DTV_AT_TP)
- memsz += tcb_offset;
- # endif
- init_static_tls (memsz, MAX (TLS_TCB_ALIGN, max_align));
- }
- /* This is called only when the data structure setup was skipped at startup,
- when there was no need for it then. Now we have dynamically loaded
- something needing TLS, or libpthread needs it. */
- int
- internal_function
- _dl_tls_setup (void)
- {
- init_slotinfo ();
- init_static_tls (
- # if defined(TLS_TCB_AT_TP)
- TLS_TCB_SIZE,
- # else
- 0,
- # endif
- TLS_TCB_ALIGN);
- return 0;
- }
- extern void __pthread_initialize_minimal(void) __attribute__((weak));
- /* This is the minimal initialization function used when libpthread is
- not used. */
- void
- __attribute__ ((weak))
- __pthread_initialize_minimal (void)
- {
- __libc_setup_tls (TLS_INIT_TCB_SIZE, TLS_INIT_TCB_ALIGN);
- }
- #endif
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