From 2208066603a136f95cfb815ca9281262e6465784 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Thu, 11 Feb 2021 13:24:47 +0000 Subject: [PATCH] elf: Remove lazy tlsdesc relocation related code 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. Reviewed-by: Adhemerval Zanella --- 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 21695fd..85bd041 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 9b6a8b0..3c1bcd8 100644 --- a/sysdeps/aarch64/tlsdesc.c +++ b/sysdeps/aarch64/tlsdesc.c @@ -22,7 +22,6 @@ #include #include #include -#define _dl_tlsdesc_resolve_hold 0 #include /* Unmap the dynamic object, but also release its TLS descriptor table diff --git a/sysdeps/arm/tlsdesc.c b/sysdeps/arm/tlsdesc.c index 2f70ade..b3d1735 100644 --- a/sysdeps/arm/tlsdesc.c +++ b/sysdeps/arm/tlsdesc.c @@ -20,7 +20,6 @@ #include #include #include -#define _dl_tlsdesc_resolve_hold 0 #include /* Unmap the dynamic object, but also release its TLS descriptor table diff --git a/sysdeps/i386/tlsdesc.c b/sysdeps/i386/tlsdesc.c index 436a21f..364c776 100644 --- a/sysdeps/i386/tlsdesc.c +++ b/sysdeps/i386/tlsdesc.c @@ -20,7 +20,6 @@ #include #include #include -#define _dl_tlsdesc_resolve_hold 0 #include /* 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 ecf864d..3bb8051 100644 --- a/sysdeps/x86_64/tlsdesc.c +++ b/sysdeps/x86_64/tlsdesc.c @@ -20,7 +20,6 @@ #include #include #include -#define _dl_tlsdesc_resolve_hold 0 #include /* Unmap the dynamic object, but also release its TLS descriptor table -- 2.7.4