From 1701d84d41369560d91baa319bd158bbd611afc1 Mon Sep 17 00:00:00 2001
From: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Fri, 20 Oct 2017 17:53:44 +0100
Subject: [PATCH 7/7] arm: Remove lazy tlsdesc initialization related code
Lazy tlsdesc initialization is no longer used in the dynamic linker
so all related code can be removed.
* sysdeps/arm/dl-machine.h (elf_machine_runtime_setup): Remove
DT_TLSDESC_GOT initialization.
* sysdeps/arm/dl-tlsdesc.S (_dl_tlsdesc_lazy_resolver): Remove.
(_dl_tlsdesc_resolve_hold): Likewise.
* sysdeps/aarch64/dl-tlsdesc.h (_dl_tlsdesc_lazy_resolver): Remove.
(_dl_tlsdesc_resolve_hold): Likewise.
* sysdeps/aarch64/tlsdesc.c (_dl_tlsdesc_lazy_resolver_fixup): Remove.
(_dl_tlsdesc_resolve_hold_fixup): Likewise.
---
sysdeps/arm/dl-machine.h | 4 --
sysdeps/arm/dl-tlsdesc.S | 84 ---------------------------------
sysdeps/arm/dl-tlsdesc.h | 4 +-
sysdeps/arm/tlsdesc.c | 119 +----------------------------------------------
4 files changed, 2 insertions(+), 209 deletions(-)
@@ -127,10 +127,6 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
got[2] = (Elf32_Addr) &_dl_runtime_resolve;
}
- if (l->l_info[ADDRIDX (DT_TLSDESC_GOT)] && lazy)
- *(Elf32_Addr*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_GOT)]) + l->l_addr)
- = (Elf32_Addr) &_dl_tlsdesc_lazy_resolver;
-
return lazy;
}
@@ -132,87 +132,3 @@ _dl_tlsdesc_dynamic:
cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
#endif /* SHARED */
-
-/* lazy resolved for tls descriptors. */
- .hidden _dl_tlsdesc_lazy_resolver
- .global _dl_tlsdesc_lazy_resolver
- .type _dl_tlsdesc_lazy_resolver,#function
- cfi_startproc
- eabi_fnstart
- .align 2
-_dl_tlsdesc_lazy_resolver:
- /* r0 points at the tlsdesc,
- r1 points at the GOT
- r2 was pushed by the trampoline and used as a temp,
- we need to pop it here.
- We push the remaining call-clobbered registers here, and also
- R1 -- to keep the stack correctly aligned. */
- /* Tell the unwinder that r2 has already been pushed. */
- eabi_save ({r2})
- cfi_adjust_cfa_offset (4)
- cfi_rel_offset (r2, 0)
- eabi_save ({r0,r1,r3,ip,lr})
- push {r0, r1, r3, ip, lr}
- cfi_adjust_cfa_offset (20)
- cfi_rel_offset (r0, 0)
- cfi_rel_offset (r1, 4)
- cfi_rel_offset (r3, 8)
- cfi_rel_offset (ip, 12)
- cfi_rel_offset (lr, 16)
- bl _dl_tlsdesc_lazy_resolver_fixup
- pop {r0, r1, r3, ip, lr}
- cfi_adjust_cfa_offset (-20)
- cfi_restore (lr)
- cfi_restore (ip)
- cfi_restore (r3)
- cfi_restore (r1)
- cfi_restore (r0)
- pop {r2}
- cfi_adjust_cfa_offset (-4)
- cfi_restore (r2)
- ldr r1, [r0, #4]
- BX (r1)
- eabi_fnend
- cfi_endproc
- .size _dl_tlsdesc_lazy_resolver, .-_dl_tlsdesc_lazy_resolver
-
-/* Holder for lazy tls descriptors being resolve in another thread.
-
- Our calling convention is to clobber r0, r1 and the processor
- flags. All others that are modified must be saved */
- .hidden _dl_tlsdesc_resolve_hold
- .global _dl_tlsdesc_resolve_hold
- .type _dl_tlsdesc_resolve_hold,#function
- cfi_startproc
- eabi_fnstart
- .align 2
-_dl_tlsdesc_resolve_hold:
- /* r0 is saved so its original value can be used after the call and
- r1 is saved only to keep the stack aligned. (r0 points to the tls
- descriptor, it is passed to _dl_tlsdesc_resolve_hold_fixup which
- is a void function that may clobber r0, later r0 is used to load
- the new resolver.) */
- eabi_save ({r0,r1,r2,r3,ip,lr})
- push {r0, r1, r2, r3, ip, lr}
- cfi_adjust_cfa_offset (24)
- cfi_rel_offset (r0, 0)
- cfi_rel_offset (r1, 4)
- cfi_rel_offset (r2, 8)
- cfi_rel_offset (r3, 12)
- cfi_rel_offset (ip, 16)
- cfi_rel_offset (lr, 20)
- adr r1, _dl_tlsdesc_resolve_hold
- bl _dl_tlsdesc_resolve_hold_fixup
- pop {r0, r1, r2, r3, ip, lr}
- cfi_adjust_cfa_offset (-24)
- cfi_restore (lr)
- cfi_restore (ip)
- cfi_restore (r3)
- cfi_restore (r2)
- cfi_restore (r1)
- cfi_restore (r0)
- ldr r1, [r0, #4]
- BX (r1)
- eabi_fnend
- cfi_endproc
- .size _dl_tlsdesc_resolve_hold, .-_dl_tlsdesc_resolve_hold
@@ -48,9 +48,7 @@ struct tlsdesc_dynamic_arg
extern ptrdiff_t attribute_hidden
_dl_tlsdesc_return(struct tlsdesc *),
- _dl_tlsdesc_undefweak(struct tlsdesc *),
- _dl_tlsdesc_resolve_hold(struct tlsdesc *),
- _dl_tlsdesc_lazy_resolver(struct tlsdesc *);
+ _dl_tlsdesc_undefweak(struct tlsdesc *);
# ifdef SHARED
extern void *_dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset);
@@ -16,130 +16,13 @@
License along with the GNU C Library. If not, see
<http://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>
-/* This function is used to lazily resolve TLS_DESC REL relocations
- Besides the TLS descriptor itself, we get the module's got address
- as the second parameter. */
-
-void
-attribute_hidden
-_dl_tlsdesc_lazy_resolver_fixup (struct tlsdesc volatile *td,
- Elf32_Addr *got)
-{
- struct link_map *l = (struct link_map *)got[1];
- lookup_t result;
- unsigned long value;
-
- if (_dl_tlsdesc_resolve_early_return_p
- (td, (void*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_PLT)]) + l->l_addr)))
- return;
-
- if (td->argument.value & 0x80000000)
- {
- /* A global symbol, this is the symbol index. */
- /* The code below was borrowed from _dl_fixup(). */
- const Elf_Symndx symndx = td->argument.value ^ 0x80000000;
- 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[symndx];
-
- /* 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[symndx] & 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);
- if (sym)
- value = sym->st_value;
- else
- {
- td->entry = _dl_tlsdesc_undefweak;
- goto done;
- }
- }
- else
- {
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- result = l;
- value = sym->st_value;
- }
- }
- else
- {
- /* A local symbol, this is the offset within our tls section.
- */
- value = td->argument.value;
- result = l;
- }
-
-#ifndef SHARED
- CHECK_STATIC_TLS (l, result);
-#else
- if (!TRY_STATIC_TLS (l, result))
- {
- td->argument.pointer = _dl_make_tlsdesc_dynamic (result, value);
- td->entry = _dl_tlsdesc_dynamic;
- }
- else
-#endif
- {
- td->argument.value = value + result->l_tls_offset;
- td->entry = _dl_tlsdesc_return;
- }
-
- done:
- _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_hidden
-_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td,
- void *caller)
-{
- /* Maybe we're lucky and can return early. */
- if (caller != 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. */
--
2.11.0