From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: libc-alpha@sourceware.org
Subject: [PATCH v2 13/14] elf: Remove lazy tlsdesc relocation related code
Date: Tue, 13 Apr 2021 09:21:41 +0100 [thread overview]
Message-ID: <f8ea2b9982e39fd950d157f5dba31121ceb51df3.1618301209.git.szabolcs.nagy@arm.com> (raw)
In-Reply-To: <cover.1618301209.git.szabolcs.nagy@arm.com>
Remove generic tlsdesc code related to lazy tlsdesc processing since
lazy tlsdesc relocation is no longer supported. This includes removing
GL(dl_load_lock) from _dl_make_tlsdesc_dynamic which is only called at
load time when that lock is already held.
Added a documentation comment too.
---
elf/tlsdeschtab.h | 53 +++++----------------------------------
sysdeps/aarch64/tlsdesc.c | 1 -
sysdeps/arm/tlsdesc.c | 1 -
sysdeps/i386/tlsdesc.c | 1 -
sysdeps/x86_64/tlsdesc.c | 1 -
5 files changed, 6 insertions(+), 51 deletions(-)
diff --git a/elf/tlsdeschtab.h b/elf/tlsdeschtab.h
index 21695fd1e9..85bd0415e1 100644
--- a/elf/tlsdeschtab.h
+++ b/elf/tlsdeschtab.h
@@ -78,6 +78,10 @@ map_generation (struct link_map *map)
return GL(dl_tls_generation) + 1;
}
+/* Returns the data pointer for a given map and tls offset that is used
+ to fill in one of the GOT entries referenced by a TLSDESC relocation
+ when using dynamic TLS. This requires allocation, returns NULL on
+ allocation failure. */
void *
_dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
{
@@ -85,18 +89,12 @@ _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
void **entry;
struct tlsdesc_dynamic_arg *td, test;
- /* FIXME: We could use a per-map lock here, but is it worth it? */
- __rtld_lock_lock_recursive (GL(dl_load_lock));
-
ht = map->l_mach.tlsdesc_table;
if (! ht)
{
ht = htab_create ();
if (! ht)
- {
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
- return 0;
- }
+ return 0;
map->l_mach.tlsdesc_table = ht;
}
@@ -104,15 +102,11 @@ _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
test.tlsinfo.ti_offset = ti_offset;
entry = htab_find_slot (ht, &test, 1, hash_tlsdesc, eq_tlsdesc);
if (! entry)
- {
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
- return 0;
- }
+ return 0;
if (*entry)
{
td = *entry;
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
return td;
}
@@ -122,44 +116,9 @@ _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
thread. */
td->gen_count = map_generation (map);
td->tlsinfo = test.tlsinfo;
-
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
return td;
}
# endif /* SHARED */
-/* The idea of the following two functions is to stop multiple threads
- from attempting to resolve the same TLS descriptor without busy
- waiting. Ideally, we should be able to release the lock right
- after changing td->entry, and then using say a condition variable
- or a futex wake to wake up any waiting threads, but let's try to
- avoid introducing such dependencies. */
-
-static int
-__attribute__ ((unused))
-_dl_tlsdesc_resolve_early_return_p (struct tlsdesc volatile *td, void *caller)
-{
- if (caller != atomic_load_relaxed (&td->entry))
- return 1;
-
- __rtld_lock_lock_recursive (GL(dl_load_lock));
- if (caller != atomic_load_relaxed (&td->entry))
- {
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
- return 1;
- }
-
- atomic_store_relaxed (&td->entry, _dl_tlsdesc_resolve_hold);
-
- return 0;
-}
-
-static void
-__attribute__ ((unused))
-_dl_tlsdesc_wake_up_held_fixups (void)
-{
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
-}
-
#endif
diff --git a/sysdeps/aarch64/tlsdesc.c b/sysdeps/aarch64/tlsdesc.c
index 9b6a8b0ec4..3c1bcd8fe6 100644
--- a/sysdeps/aarch64/tlsdesc.c
+++ b/sysdeps/aarch64/tlsdesc.c
@@ -22,7 +22,6 @@
#include <tls.h>
#include <dl-tlsdesc.h>
#include <dl-unmap-segments.h>
-#define _dl_tlsdesc_resolve_hold 0
#include <tlsdeschtab.h>
/* Unmap the dynamic object, but also release its TLS descriptor table
diff --git a/sysdeps/arm/tlsdesc.c b/sysdeps/arm/tlsdesc.c
index 2f70adef5c..b3d1735af4 100644
--- a/sysdeps/arm/tlsdesc.c
+++ b/sysdeps/arm/tlsdesc.c
@@ -20,7 +20,6 @@
#include <tls.h>
#include <dl-tlsdesc.h>
#include <dl-unmap-segments.h>
-#define _dl_tlsdesc_resolve_hold 0
#include <tlsdeschtab.h>
/* Unmap the dynamic object, but also release its TLS descriptor table
diff --git a/sysdeps/i386/tlsdesc.c b/sysdeps/i386/tlsdesc.c
index 436a21f66b..364c7769ce 100644
--- a/sysdeps/i386/tlsdesc.c
+++ b/sysdeps/i386/tlsdesc.c
@@ -20,7 +20,6 @@
#include <tls.h>
#include <dl-tlsdesc.h>
#include <dl-unmap-segments.h>
-#define _dl_tlsdesc_resolve_hold 0
#include <tlsdeschtab.h>
/* Unmap the dynamic object, but also release its TLS descriptor table
diff --git a/sysdeps/x86_64/tlsdesc.c b/sysdeps/x86_64/tlsdesc.c
index ecf864d6ee..3bb80517a3 100644
--- a/sysdeps/x86_64/tlsdesc.c
+++ b/sysdeps/x86_64/tlsdesc.c
@@ -20,7 +20,6 @@
#include <tls.h>
#include <dl-tlsdesc.h>
#include <dl-unmap-segments.h>
-#define _dl_tlsdesc_resolve_hold 0
#include <tlsdeschtab.h>
/* Unmap the dynamic object, but also release its TLS descriptor table
--
2.17.1
next prev parent reply other threads:[~2021-04-13 8:22 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-13 8:17 [PATCH v2 00/14] Dynamic TLS related data race fixes Szabolcs Nagy
2021-04-13 8:18 ` [PATCH v2 01/14] elf: Fix a DTV setup issue [BZ #27136] Szabolcs Nagy
2021-04-13 8:36 ` Andreas Schwab
2021-04-13 9:35 ` Szabolcs Nagy
2021-04-13 10:22 ` Andreas Schwab
2021-04-13 10:34 ` Szabolcs Nagy
2021-04-13 10:51 ` Andreas Schwab
2021-04-13 8:18 ` [PATCH v2 02/14] elf: Add a DTV setup test " Szabolcs Nagy
2021-04-14 18:06 ` Adhemerval Zanella
2021-04-15 9:53 ` Szabolcs Nagy
2021-04-13 8:18 ` [PATCH v2 03/14] elf: Fix comments and logic in _dl_add_to_slotinfo Szabolcs Nagy
2021-04-14 18:12 ` Adhemerval Zanella
2021-04-13 8:18 ` [PATCH v2 04/14] elf: Refactor _dl_update_slotinfo to avoid use after free Szabolcs Nagy
2021-04-14 18:20 ` Adhemerval Zanella
2021-04-13 8:19 ` [PATCH v2 05/14] elf: Fix data races in pthread_create and TLS access [BZ #19329] Szabolcs Nagy
2021-04-15 17:44 ` Adhemerval Zanella
2021-04-13 8:19 ` [PATCH v2 06/14] elf: Use relaxed atomics for racy accesses " Szabolcs Nagy
2021-04-15 18:21 ` Adhemerval Zanella
2021-04-16 9:12 ` Szabolcs Nagy
2021-05-11 2:56 ` Carlos O'Donell
2021-05-11 9:31 ` Szabolcs Nagy
2021-05-11 16:19 ` Szabolcs Nagy
2021-05-12 20:33 ` Carlos O'Donell
2021-04-13 8:19 ` [PATCH v2 07/14] elf: Add test case for " Szabolcs Nagy
2021-04-15 19:21 ` Adhemerval Zanella
2021-04-13 8:20 ` [PATCH v2 08/14] elf: Fix DTV gap reuse logic [BZ #27135] Szabolcs Nagy
2021-04-15 19:45 ` Adhemerval Zanella
2021-06-24 9:48 ` Florian Weimer
2021-06-24 12:27 ` Florian Weimer
2021-06-24 12:57 ` Adhemerval Zanella
2021-06-24 14:20 ` Florian Weimer
2021-06-24 18:58 ` Szabolcs Nagy
2021-04-13 8:20 ` [PATCH v2 09/14] x86_64: Avoid lazy relocation of tlsdesc [BZ #27137] Szabolcs Nagy
2021-04-13 14:02 ` H.J. Lu
2021-04-13 8:20 ` [PATCH v2 10/14] i386: " Szabolcs Nagy
2021-04-13 14:02 ` H.J. Lu
2021-04-13 8:21 ` [PATCH v2 11/14] x86_64: Remove lazy tlsdesc relocation related code Szabolcs Nagy
2021-04-13 14:03 ` H.J. Lu
2021-04-13 8:21 ` [PATCH v2 12/14] i386: " Szabolcs Nagy
2021-04-13 14:04 ` H.J. Lu
2021-04-13 8:21 ` Szabolcs Nagy [this message]
2021-04-15 19:52 ` [PATCH v2 13/14] elf: " Adhemerval Zanella
2021-04-13 8:21 ` [PATCH v2 14/14] RFC elf: Fix slow tls access after dlopen [BZ #19924] Szabolcs Nagy
2022-09-16 9:54 ` Carlos O'Donell
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