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[PATCH 3/4] Factor out _dl_clear_dtv
- From: Andrew Hunter <ahh at google dot com>
- To: libc-alpha at sourceware dot org, ppluzhnikov at google dot com, carlos at redhat dot com
- Cc: Andrew Hunter <ahh at google dot com>
- Date: Tue, 10 Dec 2013 16:35:42 -0800
- Subject: [PATCH 3/4] Factor out _dl_clear_dtv
- Authentication-results: sourceware.org; auth=none
- References: <1386273671-13010-1-git-send-email-ahh at google dot com> <1386722143-10513-1-git-send-email-ahh at google dot com>
This is patch 3/4 of the effort to make TLS access async-signal-safe.
We were doing some maintainance on TLS state directly from nptl code;
instead, call into dynamic linker code where the rest of the stuff
lives. This allows us (for instance) to use the proper allocator.
---
elf/Versions | 1 +
elf/dl-tls.c | 12 ++++++++++++
nptl/allocatestack.c | 6 +-----
sysdeps/generic/ldsodefs.h | 5 +++++
4 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/elf/Versions b/elf/Versions
index 2383992..01b7a59 100644
--- a/elf/Versions
+++ b/elf/Versions
@@ -53,6 +53,7 @@ ld {
_dl_allocate_tls; _dl_allocate_tls_init;
_dl_argv; _dl_find_dso_for_object; _dl_get_tls_static_info;
_dl_deallocate_tls; _dl_make_stack_executable; _dl_out_of_memory;
+ _dl_clear_dtv;
_dl_rtld_di_serinfo; _dl_starting_up; _dl_tls_setup;
_rtld_global; _rtld_global_ro;
diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index 0956b72..0cf967f 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -463,6 +463,18 @@ _dl_allocate_tls (void *mem)
}
rtld_hidden_def (_dl_allocate_tls)
+void
+internal_function
+_dl_clear_dtv (dtv_t *dtv)
+{
+ for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt)
+ if (! dtv[1 + cnt].pointer.is_static
+ && dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED)
+ __signal_safe_free (dtv[1 + cnt].pointer.val);
+ memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t));
+}
+
+rtld_hidden_def (_dl_clear_dtv)
#ifndef SHARED
extern dtv_t _dl_static_dtv[];
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 1e0fe1f..96e3845 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -242,11 +242,7 @@ get_cached_stack (size_t *sizep, void **memp)
/* Clear the DTV. */
dtv_t *dtv = GET_DTV (TLS_TPADJ (result));
- for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt)
- if (! dtv[1 + cnt].pointer.is_static
- && dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED)
- free (dtv[1 + cnt].pointer.val);
- memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t));
+ _dl_clear_dtv (dtv);
/* Re-initialize the TLS. */
_dl_allocate_tls_init (TLS_TPADJ (result));
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index adeece6..b8b420b 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -994,6 +994,11 @@ extern void __signal_safe_free (void *ptr);
extern void *__signal_safe_realloc (void *ptr, size_t size);
extern void *__signal_safe_calloc (size_t nmemb, size_t size);
+/* Remove all allocated dynamic TLS regions from a DTV
+ for reuse by new thread. */
+extern void _dl_clear_dtv (dtv_t *dtv) internal_function;
+rtld_hidden_proto (_dl_clear_dtv)
+
/* Deallocate memory allocated with _dl_allocate_tls. */
extern void _dl_deallocate_tls (void *tcb, bool dealloc_tcb) internal_function;
rtld_hidden_proto (_dl_deallocate_tls)
--
1.8.5.1