commit 5876f5032f60c45c4bd19e7ea7d0c14d0346b93e
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date: Wed May 21 16:25:53 2014 +0200
Fix TLS access for -static -pthread
I have posted:
TLS variables access for -static -lpthread executables
https://sourceware.org/ml/libc-help/2014-03/msg00024.html
and the GDB patch below has been confirmed as OK for current glibcs.
Further work should be done for newer glibcs:
Improve TLS variables glibc compatibility
https://sourceware.org/bugzilla/show_bug.cgi?id=16954
Still the patch below implements the feature in a fully functional way backward
compatible with current glibcs, it depends on the following glibc source line:
csu/libc-tls.c
main_map->l_tls_modid = 1;
gdb/
2014-05-21 Jan Kratochvil <jan.kratochvil@redhat.com>
Fix TLS access for -static -pthread.
* linux-thread-db.c (struct thread_db_info): Add td_thr_tlsbase_p.
(try_thread_db_load_1): Initialize it.
(thread_db_get_thread_local_address): Call it if LM is zero.
* target.c (target_translate_tls_address): Remove LM_ADDR zero check.
* target.h (struct target_ops) (to_get_thread_local_address): Add
load_module_addr comment.
gdb/gdbserver/
2014-05-21 Jan Kratochvil <jan.kratochvil@redhat.com>
Fix TLS access for -static -pthread.
* gdbserver/thread-db.c (struct thread_db): Add td_thr_tlsbase_p.
(thread_db_get_tls_address): Call it if LOAD_MODULE is zero.
(thread_db_load_search, try_thread_db_load_1): Initialize it.
gdb/testsuite/
2014-05-21 Jan Kratochvil <jan.kratochvil@redhat.com>
Fix TLS access for -static -pthread.
* gdb.threads/staticthreads.c <HAVE_TLS> (tlsvar): New.
<HAVE_TLS> (thread_function, main): Initialize it.
* gdb.threads/staticthreads.exp: Try gdb_compile_pthreads for $have_tls.
Add clean_restart.
<$have_tls != "">: Check TLSVAR.
Message-ID: <20140410115204.GB16411@host2.jankratochvil.net>
Index: gdb-7.6.1/gdb/gdbserver/thread-db.c
===================================================================
--- gdb-7.6.1.orig/gdb/gdbserver/thread-db.c
+++ gdb-7.6.1/gdb/gdbserver/thread-db.c
@@ -88,6 +88,9 @@ struct thread_db
td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
psaddr_t map_address,
size_t offset, psaddr_t *address);
+ td_err_e (*td_thr_tlsbase_p) (const td_thrhandle_t *th,
+ unsigned long int modid,
+ psaddr_t *base);
const char ** (*td_symbol_list_p) (void);
};
@@ -497,7 +500,10 @@ thread_db_get_tls_address (struct thread
if (thread_db == NULL || !thread_db->all_symbols_looked_up)
return TD_ERR;
- if (thread_db->td_thr_tls_get_addr_p == NULL)
+ /* If td_thr_tls_get_addr is missing rather do not expect td_thr_tlsbase
+ could work. */
+ if (thread_db->td_thr_tls_get_addr_p == NULL
+ || (load_module == 0 && thread_db->td_thr_tlsbase_p == NULL))
return -1;
lwp = get_thread_lwp (thread);
@@ -508,12 +514,28 @@ thread_db_get_tls_address (struct thread
saved_inferior = current_inferior;
current_inferior = thread;
- /* Note the cast through uintptr_t: this interface only works if
- a target address fits in a psaddr_t, which is a host pointer.
- So a 32-bit debugger can not access 64-bit TLS through this. */
- err = thread_db->td_thr_tls_get_addr_p (&lwp->th,
- (psaddr_t) (uintptr_t) load_module,
- offset, &addr);
+
+ if (load_module != 0)
+ {
+ /* Note the cast through uintptr_t: this interface only works if
+ a target address fits in a psaddr_t, which is a host pointer.
+ So a 32-bit debugger can not access 64-bit TLS through this. */
+ err = thread_db->td_thr_tls_get_addr_p (&lwp->th,
+ (psaddr_t) (uintptr_t) load_module,
+ offset, &addr);
+ }
+ else
+ {
+ /* This code path handles the case of -static -pthread executables:
+ https://sourceware.org/ml/libc-help/2014-03/msg00024.html
+ For older GNU libc r_debug.r_map is NULL. For GNU libc after
+ PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
+ The constant number 1 depends on GNU __libc_setup_tls
+ initialization of l_tls_modid to 1. */
+ err = thread_db->td_thr_tlsbase_p (&lwp->th, 1, &addr);
+ addr = (char *) addr + offset;
+ }
+
current_inferior = saved_inferior;
if (err == TD_OK)
{
@@ -565,6 +587,7 @@ thread_db_load_search (void)
tdb->td_ta_set_event_p = &td_ta_set_event;
tdb->td_ta_event_getmsg_p = &td_ta_event_getmsg;
tdb->td_thr_tls_get_addr_p = &td_thr_tls_get_addr;
+ tdb->td_thr_tlsbase_p = &td_thr_tlsbase;
return 1;
}
@@ -633,6 +656,7 @@ try_thread_db_load_1 (void *handle)
CHK (0, tdb->td_ta_set_event_p = dlsym (handle, "td_ta_set_event"));
CHK (0, tdb->td_ta_event_getmsg_p = dlsym (handle, "td_ta_event_getmsg"));
CHK (0, tdb->td_thr_tls_get_addr_p = dlsym (handle, "td_thr_tls_get_addr"));
+ CHK (0, tdb->td_thr_tlsbase_p = dlsym (handle, "td_thr_tlsbase"));
#undef CHK
Index: gdb-7.6.1/gdb/linux-thread-db.c
===================================================================
--- gdb-7.6.1.orig/gdb/linux-thread-db.c
+++ gdb-7.6.1/gdb/linux-thread-db.c
@@ -196,6 +196,9 @@ struct thread_db_info
td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
psaddr_t map_address,
size_t offset, psaddr_t *address);
+ td_err_e (*td_thr_tlsbase_p) (const td_thrhandle_t *th,
+ unsigned long int modid,
+ psaddr_t *base);
};
/* List of known processes using thread_db, and the required
@@ -797,6 +800,7 @@ try_thread_db_load_1 (struct thread_db_i
info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg");
info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable");
info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr");
+ info->td_thr_tlsbase_p = dlsym (info->handle, "td_thr_tlsbase");
if (thread_db_find_new_threads_silently (inferior_ptid) != 0)
{
@@ -1798,21 +1802,39 @@ thread_db_get_thread_local_address (stru
info = get_thread_db_info (GET_PID (ptid));
- /* glibc doesn't provide the needed interface. */
- if (!info->td_thr_tls_get_addr_p)
- throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
- _("No TLS library support"));
-
- /* Caller should have verified that lm != 0. */
- gdb_assert (lm != 0);
-
/* Finally, get the address of the variable. */
- /* Note the cast through uintptr_t: this interface only works if
- a target address fits in a psaddr_t, which is a host pointer.
- So a 32-bit debugger can not access 64-bit TLS through this. */
- err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
- (psaddr_t)(uintptr_t) lm,
- offset, &address);
+ if (lm != 0)
+ {
+ /* glibc doesn't provide the needed interface. */
+ if (!info->td_thr_tls_get_addr_p)
+ throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
+ _("No TLS library support"));
+
+ /* Note the cast through uintptr_t: this interface only works if
+ a target address fits in a psaddr_t, which is a host pointer.
+ So a 32-bit debugger can not access 64-bit TLS through this. */
+ err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
+ (psaddr_t)(uintptr_t) lm,
+ offset, &address);
+ }
+ else
+ {
+ /* If glibc doesn't provide the needed interface throw an error
+ that LM is zero - normally cases it should not be. */
+ if (!info->td_thr_tlsbase_p)
+ throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR,
+ _("TLS load module not found"));
+
+ /* This code path handles the case of -static -pthread executables:
+ https://sourceware.org/ml/libc-help/2014-03/msg00024.html
+ For older GNU libc r_debug.r_map is NULL. For GNU libc after
+ PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
+ The constant number 1 depends on GNU __libc_setup_tls
+ initialization of l_tls_modid to 1. */
+ err = info->td_thr_tlsbase_p (&thread_info->private->th,
+ 1, &address);
+ address = (char *) address + offset;
+ }
#ifdef THREAD_DB_HAS_TD_NOTALLOC
/* The memory hasn't been allocated, yet. */
Index: gdb-7.6.1/gdb/target.c
===================================================================
--- gdb-7.6.1.orig/gdb/target.c
+++ gdb-7.6.1/gdb/target.c
@@ -1165,10 +1165,6 @@ target_translate_tls_address (struct obj
/* Fetch the load module address for this objfile. */
lm_addr = gdbarch_fetch_tls_load_module_address (target_gdbarch (),
objfile);
- /* If it's 0, throw the appropriate exception. */
- if (lm_addr == 0)
- throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR,
- _("TLS load module not found"));
addr = target->to_get_thread_local_address (target, ptid,
lm_addr, offset);
Index: gdb-7.6.1/gdb/target.h
===================================================================
--- gdb-7.6.1.orig/gdb/target.h
+++ gdb-7.6.1/gdb/target.h
@@ -557,7 +557,8 @@ struct target_ops
thread-local storage for the thread PTID and the shared library
or executable file given by OBJFILE. If that block of
thread-local storage hasn't been allocated yet, this function
- may return an error. */
+ may return an error. LOAD_MODULE_ADDR may be zero for statically
+ linked multithreaded inferiors. */
CORE_ADDR (*to_get_thread_local_address) (struct target_ops *ops,
ptid_t ptid,
CORE_ADDR load_module_addr,
Index: gdb-7.6.1/gdb/testsuite/gdb.threads/staticthreads.c
===================================================================
--- gdb-7.6.1.orig/gdb/testsuite/gdb.threads/staticthreads.c
+++ gdb-7.6.1/gdb/testsuite/gdb.threads/staticthreads.c
@@ -28,10 +28,17 @@
sem_t semaphore;
+#ifdef HAVE_TLS
+__thread int tlsvar;
+#endif
+
void *
thread_function (void *arg)
{
- printf ("Thread executing\n");
+#ifdef HAVE_TLS
+ tlsvar = 2;
+#endif
+ printf ("Thread executing\n"); /* tlsvar-is-set */
while (sem_wait (&semaphore) != 0)
{
if (errno != EINTR)
@@ -57,6 +64,9 @@ main (int argc, char **argv)
return -1;
}
+#ifdef HAVE_TLS
+ tlsvar = 1;
+#endif
/* Create a thread, wait for it to complete. */
{
Index: gdb-7.6.1/gdb/testsuite/gdb.threads/staticthreads.exp
===================================================================
--- gdb-7.6.1.orig/gdb/testsuite/gdb.threads/staticthreads.exp
+++ gdb-7.6.1/gdb/testsuite/gdb.threads/staticthreads.exp
@@ -22,11 +22,16 @@
standard_testfile
set static_flag "-static"
-if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
- executable \
- [list debug "additional_flags=${static_flag}" \
- ]] != "" } {
- return -1
+foreach have_tls { "-DHAVE_TLS" "" } {
+ if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
+ executable \
+ [list debug "additional_flags=${static_flag} ${have_tls}" \
+ ]] == "" } {
+ break
+ }
+ if { $have_tls == "" } {
+ return -1
+ }
}
clean_restart ${binfile}
@@ -96,3 +101,18 @@ gdb_test_multiple "quit" "$test" {
pass "$test"
}
}
+clean_restart ${binfile}
+
+
+if { "$have_tls" != "" } {
+ if ![runto_main] {
+ return -1
+ }
+ gdb_breakpoint [gdb_get_line_number "tlsvar-is-set"]
+ gdb_continue_to_breakpoint "tlsvar-is-set" ".* tlsvar-is-set .*"
+ gdb_test "p tlsvar" " = 2" "tlsvar in thread"
+ gdb_test "thread 1" ".*"
+ # Unwind from pthread_join.
+ gdb_test "up 10" " in main .*"
+ gdb_test "p tlsvar" " = 1" "tlsvar in main"
+}