cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
#endif /* SHARED */
-
- /* This function is a wrapper for a lazy resolver for TLS_DESC
- REL relocations that reference the *ABS* segment in their own
- link maps. %ebx points to the caller's GOT. %eax points to a
- TLS descriptor, such that 0(%eax) holds the address of the
- resolver wrapper itself (unless some other thread beat us to
- it) and 4(%eax) holds the addend in the relocation.
-
- When the actual resolver returns, it will have adjusted the
- TLS descriptor such that we can tail-call it for it to return
- the TP offset of the symbol. */
-
- .hidden _dl_tlsdesc_resolve_abs_plus_addend
- .global _dl_tlsdesc_resolve_abs_plus_addend
- .type _dl_tlsdesc_resolve_abs_plus_addend,@function
- cfi_startproc
- .align 16
-_dl_tlsdesc_resolve_abs_plus_addend:
-0:
- _CET_ENDBR
- pushl %eax
- cfi_adjust_cfa_offset (4)
- pushl %ecx
- cfi_adjust_cfa_offset (4)
- pushl %edx
- cfi_adjust_cfa_offset (4)
- movl $1f - 0b, %ecx
- movl 4(%ebx), %edx
- call _dl_tlsdesc_resolve_abs_plus_addend_fixup
-1:
- popl %edx
- cfi_adjust_cfa_offset (-4)
- popl %ecx
- cfi_adjust_cfa_offset (-4)
- popl %eax
- cfi_adjust_cfa_offset (-4)
- jmp *(%eax)
- cfi_endproc
- .size _dl_tlsdesc_resolve_abs_plus_addend, .-_dl_tlsdesc_resolve_abs_plus_addend
-
- /* This function is a wrapper for a lazy resolver for TLS_DESC
- REL relocations that had zero addends. %ebx points to the
- caller's GOT. %eax points to a TLS descriptor, such that
- 0(%eax) holds the address of the resolver wrapper itself
- (unless some other thread beat us to it) and 4(%eax) holds a
- pointer to the relocation.
-
- When the actual resolver returns, it will have adjusted the
- TLS descriptor such that we can tail-call it for it to return
- the TP offset of the symbol. */
-
- .hidden _dl_tlsdesc_resolve_rel
- .global _dl_tlsdesc_resolve_rel
- .type _dl_tlsdesc_resolve_rel,@function
- cfi_startproc
- .align 16
-_dl_tlsdesc_resolve_rel:
-0:
- _CET_ENDBR
- pushl %eax
- cfi_adjust_cfa_offset (4)
- pushl %ecx
- cfi_adjust_cfa_offset (4)
- pushl %edx
- cfi_adjust_cfa_offset (4)
- movl $1f - 0b, %ecx
- movl 4(%ebx), %edx
- call _dl_tlsdesc_resolve_rel_fixup
-1:
- popl %edx
- cfi_adjust_cfa_offset (-4)
- popl %ecx
- cfi_adjust_cfa_offset (-4)
- popl %eax
- cfi_adjust_cfa_offset (-4)
- jmp *(%eax)
- cfi_endproc
- .size _dl_tlsdesc_resolve_rel, .-_dl_tlsdesc_resolve_rel
-
- /* This function is a wrapper for a lazy resolver for TLS_DESC
- RELA relocations. %ebx points to the caller's GOT. %eax
- points to a TLS descriptor, such that 0(%eax) holds the
- address of the resolver wrapper itself (unless some other
- thread beat us to it) and 4(%eax) holds a pointer to the
- relocation.
-
- When the actual resolver returns, it will have adjusted the
- TLS descriptor such that we can tail-call it for it to return
- the TP offset of the symbol. */
-
- .hidden _dl_tlsdesc_resolve_rela
- .global _dl_tlsdesc_resolve_rela
- .type _dl_tlsdesc_resolve_rela,@function
- cfi_startproc
- .align 16
-_dl_tlsdesc_resolve_rela:
-0:
- _CET_ENDBR
- pushl %eax
- cfi_adjust_cfa_offset (4)
- pushl %ecx
- cfi_adjust_cfa_offset (4)
- pushl %edx
- cfi_adjust_cfa_offset (4)
- movl $1f - 0b, %ecx
- movl 4(%ebx), %edx
- call _dl_tlsdesc_resolve_rela_fixup
-1:
- popl %edx
- cfi_adjust_cfa_offset (-4)
- popl %ecx
- cfi_adjust_cfa_offset (-4)
- popl %eax
- cfi_adjust_cfa_offset (-4)
- jmp *(%eax)
- cfi_endproc
- .size _dl_tlsdesc_resolve_rela, .-_dl_tlsdesc_resolve_rela
-
- /* This function is a placeholder for lazy resolving of TLS
- relocations. Once some thread starts resolving a TLS
- relocation, it sets up the TLS descriptor to use this
- resolver, such that other threads that would attempt to
- resolve it concurrently may skip the call to the original lazy
- resolver and go straight to a condition wait.
-
- When the actual resolver returns, it will have adjusted the
- TLS descriptor such that we can tail-call it for it to return
- the TP offset of the symbol. */
-
- .hidden _dl_tlsdesc_resolve_hold
- .global _dl_tlsdesc_resolve_hold
- .type _dl_tlsdesc_resolve_hold,@function
- cfi_startproc
- .align 16
-_dl_tlsdesc_resolve_hold:
-0:
- _CET_ENDBR
- pushl %eax
- cfi_adjust_cfa_offset (4)
- pushl %ecx
- cfi_adjust_cfa_offset (4)
- pushl %edx
- cfi_adjust_cfa_offset (4)
- movl $1f - 0b, %ecx
- movl 4(%ebx), %edx
- call _dl_tlsdesc_resolve_hold_fixup
-1:
- popl %edx
- cfi_adjust_cfa_offset (-4)
- popl %ecx
- cfi_adjust_cfa_offset (-4)
- popl %eax
- cfi_adjust_cfa_offset (-4)
- jmp *(%eax)
- cfi_endproc
- .size _dl_tlsdesc_resolve_hold, .-_dl_tlsdesc_resolve_hold
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <link.h>
#include <ldsodefs.h>
-#include <elf/dynamic-link.h>
#include <tls.h>
#include <dl-tlsdesc.h>
#include <dl-unmap-segments.h>
+#define _dl_tlsdesc_resolve_hold 0
#include <tlsdeschtab.h>
-/* The following 4 functions take an entry_check_offset argument.
- It's computed by the caller as an offset between its entry point
- and the call site, such that by adding the built-in return address
- that is implicitly passed to the function with this offset, we can
- easily obtain the caller's entry point to compare with the entry
- point given in the TLS descriptor. If it's changed, we want to
- return immediately. */
-
-/* This function is used to lazily resolve TLS_DESC REL relocations
- that reference the *ABS* segment in their own link maps. The
- argument is the addend originally stored there. */
-
-void
-__attribute__ ((regparm (3))) attribute_hidden
-_dl_tlsdesc_resolve_abs_plus_addend_fixup (struct tlsdesc volatile *td,
- struct link_map *l,
- ptrdiff_t entry_check_offset)
-{
- ptrdiff_t addend = (ptrdiff_t) td->arg;
-
- if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
- - entry_check_offset))
- return;
-
-#ifndef SHARED
- CHECK_STATIC_TLS (l, l);
-#else
- if (!TRY_STATIC_TLS (l, l))
- {
- td->arg = _dl_make_tlsdesc_dynamic (l, addend);
- td->entry = _dl_tlsdesc_dynamic;
- }
- else
-#endif
- {
- td->arg = (void*) (addend - l->l_tls_offset);
- td->entry = _dl_tlsdesc_return;
- }
-
- _dl_tlsdesc_wake_up_held_fixups ();
-}
-
-/* This function is used to lazily resolve TLS_DESC REL relocations
- that originally had zero addends. The argument location, that
- originally held the addend, is used to hold a pointer to the
- relocation, but it has to be restored before we call the function
- that applies relocations. */
-
-void
-__attribute__ ((regparm (3))) attribute_hidden
-_dl_tlsdesc_resolve_rel_fixup (struct tlsdesc volatile *td,
- struct link_map *l,
- ptrdiff_t entry_check_offset)
-{
- const ElfW(Rel) *reloc = td->arg;
-
- if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
- - entry_check_offset))
- return;
-
- /* The code below was borrowed from _dl_fixup(),
- except for checking for STB_LOCAL. */
- const ElfW(Sym) *const symtab
- = (const void *) D_PTR (l, l_info[DT_SYMTAB]);
- const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
- const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
- lookup_t result;
-
- /* Look up the target symbol. If the normal lookup rules are not
- used don't look in the global scope. */
- if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
- && __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
- {
- const struct r_found_version *version = NULL;
-
- if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
- {
- const ElfW(Half) *vernum =
- (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
- version = &l->l_versions[ndx];
- if (version->hash == 0)
- version = NULL;
- }
-
- result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
- l->l_scope, version, ELF_RTYPE_CLASS_PLT,
- DL_LOOKUP_ADD_DEPENDENCY, NULL);
- }
- else
- {
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- result = l;
- }
-
- if (!sym)
- {
- td->arg = 0;
- td->entry = _dl_tlsdesc_undefweak;
- }
- else
- {
-# ifndef SHARED
- CHECK_STATIC_TLS (l, result);
-# else
- if (!TRY_STATIC_TLS (l, result))
- {
- td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value);
- td->entry = _dl_tlsdesc_dynamic;
- }
- else
-# endif
- {
- td->arg = (void*)(sym->st_value - result->l_tls_offset);
- td->entry = _dl_tlsdesc_return;
- }
- }
-
- _dl_tlsdesc_wake_up_held_fixups ();
-}
-
-/* This function is used to lazily resolve TLS_DESC RELA relocations.
- The argument location is used to hold a pointer to the relocation. */
-
-void
-__attribute__ ((regparm (3))) attribute_hidden
-_dl_tlsdesc_resolve_rela_fixup (struct tlsdesc volatile *td,
- struct link_map *l,
- ptrdiff_t entry_check_offset)
-{
- const ElfW(Rela) *reloc = td->arg;
-
- if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
- - entry_check_offset))
- return;
-
- /* The code below was borrowed from _dl_fixup(),
- except for checking for STB_LOCAL. */
- const ElfW(Sym) *const symtab
- = (const void *) D_PTR (l, l_info[DT_SYMTAB]);
- const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
- const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
- lookup_t result;
-
- /* Look up the target symbol. If the normal lookup rules are not
- used don't look in the global scope. */
- if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
- && __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
- {
- const struct r_found_version *version = NULL;
-
- if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
- {
- const ElfW(Half) *vernum =
- (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
- version = &l->l_versions[ndx];
- if (version->hash == 0)
- version = NULL;
- }
-
- result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
- l->l_scope, version, ELF_RTYPE_CLASS_PLT,
- DL_LOOKUP_ADD_DEPENDENCY, NULL);
- }
- else
- {
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- result = l;
- }
-
- if (!sym)
- {
- td->arg = (void*) reloc->r_addend;
- td->entry = _dl_tlsdesc_undefweak;
- }
- else
- {
-# ifndef SHARED
- CHECK_STATIC_TLS (l, result);
-# else
- if (!TRY_STATIC_TLS (l, result))
- {
- td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value
- + reloc->r_addend);
- td->entry = _dl_tlsdesc_dynamic;
- }
- else
-# endif
- {
- td->arg = (void*) (sym->st_value - result->l_tls_offset
- + reloc->r_addend);
- td->entry = _dl_tlsdesc_return;
- }
- }
-
- _dl_tlsdesc_wake_up_held_fixups ();
-}
-
-/* This function is used to avoid busy waiting for other threads to
- complete the lazy relocation. Once another thread wins the race to
- relocate a TLS descriptor, it sets the descriptor up such that this
- function is called to wait until the resolver releases the
- lock. */
-
-void
-__attribute__ ((regparm (3))) attribute_hidden
-_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td,
- struct link_map *l __attribute__((__unused__)),
- ptrdiff_t entry_check_offset)
-{
- /* Maybe we're lucky and can return early. */
- if (__builtin_return_address (0) - entry_check_offset != td->entry)
- return;
-
- /* Locking here will stop execution until the running resolver runs
- _dl_tlsdesc_wake_up_held_fixups(), releasing the lock.
-
- FIXME: We'd be better off waiting on a condition variable, such
- that we didn't have to hold the lock throughout the relocation
- processing. */
- __rtld_lock_lock_recursive (GL(dl_load_lock));
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
-}
-
-
/* Unmap the dynamic object, but also release its TLS descriptor table
if there is one. */
git://sourceware.org / glibc.git / commitdiff