[v2,12/14] i386: Remove lazy tlsdesc relocation related code
Commit Message
Like in commit e75711ebfa976d5468ec292282566a18b07e4d67 for x86_64,
remove unused lazy tlsdesc relocation processing code:
_dl_tlsdesc_resolve_abs_plus_addend
_dl_tlsdesc_resolve_rel
_dl_tlsdesc_resolve_rela
_dl_tlsdesc_resolve_hold
---
sysdeps/i386/dl-tlsdesc.S | 156 -------------------------
sysdeps/i386/dl-tlsdesc.h | 6 +-
sysdeps/i386/tlsdesc.c | 231 +-------------------------------------
3 files changed, 2 insertions(+), 391 deletions(-)
Comments
On Tue, Apr 13, 2021 at 2:34 AM Szabolcs Nagy via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> Like in commit e75711ebfa976d5468ec292282566a18b07e4d67 for x86_64,
> remove unused lazy tlsdesc relocation processing code:
>
> _dl_tlsdesc_resolve_abs_plus_addend
> _dl_tlsdesc_resolve_rel
> _dl_tlsdesc_resolve_rela
> _dl_tlsdesc_resolve_hold
> ---
> sysdeps/i386/dl-tlsdesc.S | 156 -------------------------
> sysdeps/i386/dl-tlsdesc.h | 6 +-
> sysdeps/i386/tlsdesc.c | 231 +-------------------------------------
> 3 files changed, 2 insertions(+), 391 deletions(-)
>
> diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
> index e781d973b7..255fe88651 100644
> --- a/sysdeps/i386/dl-tlsdesc.S
> +++ b/sysdeps/i386/dl-tlsdesc.S
> @@ -134,159 +134,3 @@ _dl_tlsdesc_dynamic:
> 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
> diff --git a/sysdeps/i386/dl-tlsdesc.h b/sysdeps/i386/dl-tlsdesc.h
> index 753c03e79c..12e90da3a8 100644
> --- a/sysdeps/i386/dl-tlsdesc.h
> +++ b/sysdeps/i386/dl-tlsdesc.h
> @@ -43,11 +43,7 @@ struct tlsdesc_dynamic_arg
>
> extern ptrdiff_t attribute_hidden __attribute__ ((regparm (1)))
> _dl_tlsdesc_return (struct tlsdesc *),
> - _dl_tlsdesc_undefweak (struct tlsdesc *),
> - _dl_tlsdesc_resolve_abs_plus_addend (struct tlsdesc *),
> - _dl_tlsdesc_resolve_rel (struct tlsdesc *),
> - _dl_tlsdesc_resolve_rela (struct tlsdesc *),
> - _dl_tlsdesc_resolve_hold (struct tlsdesc *);
> + _dl_tlsdesc_undefweak (struct tlsdesc *);
>
> # ifdef SHARED
> extern void *_dl_make_tlsdesc_dynamic (struct link_map *map,
> diff --git a/sysdeps/i386/tlsdesc.c b/sysdeps/i386/tlsdesc.c
> index 0bc646541f..436a21f66b 100644
> --- a/sysdeps/i386/tlsdesc.c
> +++ b/sysdeps/i386/tlsdesc.c
> @@ -16,242 +16,13 @@
> 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. */
>
> --
> 2.17.1
>
LGTM.
Thanks.
@@ -134,159 +134,3 @@ _dl_tlsdesc_dynamic:
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
@@ -43,11 +43,7 @@ struct tlsdesc_dynamic_arg
extern ptrdiff_t attribute_hidden __attribute__ ((regparm (1)))
_dl_tlsdesc_return (struct tlsdesc *),
- _dl_tlsdesc_undefweak (struct tlsdesc *),
- _dl_tlsdesc_resolve_abs_plus_addend (struct tlsdesc *),
- _dl_tlsdesc_resolve_rel (struct tlsdesc *),
- _dl_tlsdesc_resolve_rela (struct tlsdesc *),
- _dl_tlsdesc_resolve_hold (struct tlsdesc *);
+ _dl_tlsdesc_undefweak (struct tlsdesc *);
# ifdef SHARED
extern void *_dl_make_tlsdesc_dynamic (struct link_map *map,
@@ -16,242 +16,13 @@
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. */