diff mbox

[7/7] arm: Remove lazy tlsdesc initialization related code

Message ID 59EF4F27.3020009@arm.com
State New, archived
Headers show

Commit Message

Szabolcs Nagy Oct. 24, 2017, 2:33 p.m. UTC
2017-10-23  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* 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.
diff mbox

Patch

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(-)

diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h
index ec3a0274e3..fb5468a93b 100644
--- a/sysdeps/arm/dl-machine.h
+++ b/sysdeps/arm/dl-machine.h
@@ -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;
 }
 
diff --git a/sysdeps/arm/dl-tlsdesc.S b/sysdeps/arm/dl-tlsdesc.S
index e7bed02188..99d4b8327f 100644
--- a/sysdeps/arm/dl-tlsdesc.S
+++ b/sysdeps/arm/dl-tlsdesc.S
@@ -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
diff --git a/sysdeps/arm/dl-tlsdesc.h b/sysdeps/arm/dl-tlsdesc.h
index 2770af0260..bb2c731e74 100644
--- a/sysdeps/arm/dl-tlsdesc.h
+++ b/sysdeps/arm/dl-tlsdesc.h
@@ -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);
diff --git a/sysdeps/arm/tlsdesc.c b/sysdeps/arm/tlsdesc.c
index ad79506178..329f26e308 100644
--- a/sysdeps/arm/tlsdesc.c
+++ b/sysdeps/arm/tlsdesc.c
@@ -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