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jobcore/glibc/0001-nptl_db-Support-different-libpthread-ld.so-load-orde.patch
joborun linux d73f6728dc upgrade
2022-03-20 14:19:37 +02:00

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From a64afc225240b2b27129ccfb0516d7c958b98040 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 21 Apr 2021 11:50:43 +0200
Subject: [PATCH 364/576] nptl_db: Support different libpthread/ld.so load
orders (bug 27744)
libthread_db is loaded once GDB encounters libpthread, and at this
point, ld.so may not have been processed by GDB yet. As a result,
_rtld_global cannot be accessed by regular means from libthread_db.
To make this work until GDB can be fixed, acess _rtld_global through
a pointer stored in libpthread.
The new test does not reproduce bug 27744 with
--disable-hardcoded-path-in-tests, but is still a valid smoke test.
With --enable-hardcoded-path-in-tests, it is necessary to avoid
add-symbol-file because this can tickle a GDB bug.
Fixes commit 1daccf403b1bd86370eb94edca794dc106d02039 ("nptl: Move
stack list variables into _rtld_global").
Tested-by: Emil Velikov <emil.velikov@collabora.com>
---
nptl/Makefile | 19 +++-
nptl/pthread_create.c | 8 ++
nptl/tst-pthread-gdb-attach-static.c | 1 +
nptl/tst-pthread-gdb-attach.c | 143 +++++++++++++++++++++++++++
nptl_db/structs.def | 3 +-
nptl_db/td_init.c | 15 +--
nptl_db/thread_dbP.h | 2 +
7 files changed, 180 insertions(+), 11 deletions(-)
create mode 100644 nptl/tst-pthread-gdb-attach-static.c
create mode 100644 nptl/tst-pthread-gdb-attach.c
diff --git a/nptl/Makefile b/nptl/Makefile
index 8fe92d43fa..e665d37e52 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -313,7 +313,8 @@ tests = tst-attr2 tst-attr3 tst-default-attr \
tst-thread-affinity-sched \
tst-pthread-defaultattr-free \
tst-pthread-attr-sigmask \
- tst-pthread-timedlock-lockloop
+ tst-pthread-timedlock-lockloop \
+ tst-pthread-gdb-attach tst-pthread-gdb-attach-static
tests-container = tst-pthread-getattr
@@ -359,6 +360,19 @@ CPPFLAGS-test-cond-printers.c := $(CFLAGS-printers-tests)
CPPFLAGS-test-rwlockattr-printers.c := $(CFLAGS-printers-tests)
CPPFLAGS-test-rwlock-printers.c := $(CFLAGS-printers-tests)
+# Reuse the CFLAGS setting for the GDB attaching test. It needs
+# debugging information.
+CFLAGS-tst-pthread-gdb-attach.c := $(CFLAGS-printers-tests)
+CPPFLAGS-tst-pthread-gdb-attach.c := $(CFLAGS-printers-tests)
+ifeq ($(build-shared)$(build-hardcoded-path-in-tests),yesno)
+CPPFLAGS-tst-pthread-gdb-attach.c += -DDO_ADD_SYMBOL_FILE=1
+else
+CPPFLAGS-tst-pthread-gdb-attach.c += -DDO_ADD_SYMBOL_FILE=0
+endif
+CFLAGS-tst-pthread-gdb-attach-static.c := $(CFLAGS-printers-tests)
+CPPFLAGS-tst-pthread-gdb-attach-static.c := \
+ $(CFLAGS-printers-tests) -DDO_ADD_SYMBOL_FILE=0
+
ifeq ($(build-shared),yes)
tests-printers-libs := $(shared-thread-library)
else
@@ -430,7 +444,8 @@ link-libc-static := $(common-objpfx)libc.a $(static-gnulib) \
tests-static += tst-stackguard1-static \
tst-cancel24-static \
tst-mutex8-static tst-mutexpi8-static tst-sem11-static \
- tst-sem12-static tst-cond11-static
+ tst-sem12-static tst-cond11-static \
+ tst-pthread-gdb-attach-static
tests += tst-cancel24-static
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 6c645aff48..f13d8e44a4 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -51,6 +51,14 @@ static td_thr_events_t __nptl_threads_events __attribute_used__;
/* Pointer to descriptor with the last event. */
static struct pthread *__nptl_last_event __attribute_used__;
+#ifdef SHARED
+/* This variable is used to access _rtld_global from libthread_db. If
+ GDB loads libpthread before ld.so, it is not possible to resolve
+ _rtld_global directly during libpthread initialization. */
+static struct rtld_global *__nptl_rtld_global __attribute_used__
+ = &_rtld_global;
+#endif
+
/* Number of threads running. */
unsigned int __nptl_nthreads = 1;
diff --git a/nptl/tst-pthread-gdb-attach-static.c b/nptl/tst-pthread-gdb-attach-static.c
new file mode 100644
index 0000000000..e159632cac
--- /dev/null
+++ b/nptl/tst-pthread-gdb-attach-static.c
@@ -0,0 +1 @@
+#include "tst-pthread-gdb-attach.c"
diff --git a/nptl/tst-pthread-gdb-attach.c b/nptl/tst-pthread-gdb-attach.c
new file mode 100644
index 0000000000..0603ad844d
--- /dev/null
+++ b/nptl/tst-pthread-gdb-attach.c
@@ -0,0 +1,143 @@
+/* Smoke testing GDB process attach with thread-local variable access.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+/* This test runs GDB against a forked copy of itself, to check
+ whether libthread_db can be loaded, and that access to thread-local
+ variables works. */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/test-driver.h>
+#include <support/xstdio.h>
+#include <support/xthread.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+/* Starts out as zero, changed to 1 or 2 by the debugger, depending on
+ the thread. */
+__thread volatile int altered_by_debugger;
+
+/* Writes the GDB script to run the test to PATH. */
+static void
+write_gdbscript (const char *path, int tested_pid)
+{
+ FILE *fp = xfopen (path, "w");
+ fprintf (fp,
+ "set trace-commands on\n"
+ "set debug libthread-db 1\n"
+#if DO_ADD_SYMBOL_FILE
+ /* Do not do this unconditionally to work around a GDB
+ assertion failure: ../../gdb/symtab.c:6404:
+ internal-error: CORE_ADDR get_msymbol_address(objfile*,
+ const minimal_symbol*): Assertion `(objf->flags &
+ OBJF_MAINLINE) == 0' failed. */
+ "add-symbol-file %1$s/nptl/tst-pthread-gdb-attach\n"
+#endif
+ "set auto-load safe-path %1$s/nptl_db\n"
+ "set libthread-db-search-path %1$s/nptl_db\n"
+ "attach %2$d\n",
+ support_objdir_root, tested_pid);
+ fputs ("break debugger_inspection_point\n"
+ "continue\n"
+ "thread 1\n"
+ "print altered_by_debugger\n"
+ "print altered_by_debugger = 1\n"
+ "thread 2\n"
+ "print altered_by_debugger\n"
+ "print altered_by_debugger = 2\n"
+ "continue\n",
+ fp);
+ xfclose (fp);
+}
+
+/* The test sets a breakpoint on this function and alters the
+ altered_by_debugger thread-local variable. */
+void __attribute__ ((weak))
+debugger_inspection_point (void)
+{
+}
+
+/* Thread function for the test thread in the subprocess. */
+static void *
+subprocess_thread (void *closure)
+{
+ /* Wait until altered_by_debugger changes the value away from 0. */
+ while (altered_by_debugger == 0)
+ {
+ usleep (100 * 1000);
+ debugger_inspection_point ();
+ }
+
+ TEST_COMPARE (altered_by_debugger, 2);
+ return NULL;
+}
+
+/* This function implements the subprocess under test. It creates a
+ second thread, waiting for its value to change to 2, and checks
+ that the main thread also changed its value to 1. */
+static void
+in_subprocess (void)
+{
+ pthread_t thr = xpthread_create (NULL, subprocess_thread, NULL);
+ TEST_VERIFY (xpthread_join (thr) == NULL);
+ TEST_COMPARE (altered_by_debugger, 1);
+ _exit (0);
+}
+
+static int
+do_test (void)
+{
+ pid_t tested_pid = xfork ();
+ if (tested_pid == 0)
+ in_subprocess ();
+ char *tested_pid_string = xasprintf ("%d", tested_pid);
+
+ char *gdbscript;
+ xclose (create_temp_file ("tst-pthread-gdb-attach-", &gdbscript));
+ write_gdbscript (gdbscript, tested_pid);
+
+ pid_t gdb_pid = xfork ();
+ if (gdb_pid == 0)
+ {
+ clearenv ();
+ xdup2 (STDOUT_FILENO, STDERR_FILENO);
+ execlp ("gdb", "gdb", "-nx", "-batch", "-x", gdbscript, NULL);
+ if (errno == ENOENT)
+ _exit (EXIT_UNSUPPORTED);
+ else
+ _exit (1);
+ }
+
+ int status;
+ TEST_COMPARE (xwaitpid (gdb_pid, &status, 0), gdb_pid);
+ if (WIFEXITED (status) && WEXITSTATUS (status) == EXIT_UNSUPPORTED)
+ /* gdb is not installed. */
+ return EXIT_UNSUPPORTED;
+ TEST_COMPARE (status, 0);
+ TEST_COMPARE (xwaitpid (tested_pid, &status, 0), tested_pid);
+ TEST_COMPARE (status, 0);
+
+ free (tested_pid_string);
+ free (gdbscript);
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/nptl_db/structs.def b/nptl_db/structs.def
index 999a9fc35a..8a613dd2f5 100644
--- a/nptl_db/structs.def
+++ b/nptl_db/structs.def
@@ -100,8 +100,7 @@ DB_STRUCT_FIELD (pthread, dtvp)
#endif
#if !(IS_IN (libpthread) && !defined SHARED)
-DB_STRUCT (rtld_global)
-DB_RTLD_VARIABLE (_rtld_global)
+DB_VARIABLE (__nptl_rtld_global)
#endif
DB_RTLD_GLOBAL_FIELD (dl_tls_dtv_slotinfo_list)
DB_RTLD_GLOBAL_FIELD (dl_stack_user)
diff --git a/nptl_db/td_init.c b/nptl_db/td_init.c
index 1d15681228..06b5adc5c2 100644
--- a/nptl_db/td_init.c
+++ b/nptl_db/td_init.c
@@ -33,13 +33,14 @@ td_init (void)
bool
__td_ta_rtld_global (td_thragent_t *ta)
{
- if (ta->ta_addr__rtld_global == 0
- && td_mod_lookup (ta->ph, LD_SO, SYM__rtld_global,
- &ta->ta_addr__rtld_global) != PS_OK)
+ if (ta->ta_addr__rtld_global == 0)
{
- ta->ta_addr__rtld_global = (void*)-1;
- return false;
+ psaddr_t rtldglobalp;
+ if (DB_GET_VALUE (rtldglobalp, ta, __nptl_rtld_global, 0) == TD_OK)
+ ta->ta_addr__rtld_global = rtldglobalp;
+ else
+ ta->ta_addr__rtld_global = (void *) -1;
}
- else
- return ta->ta_addr__rtld_global != (void*)-1;
+
+ return ta->ta_addr__rtld_global != (void *)-1;
}
diff --git a/nptl_db/thread_dbP.h b/nptl_db/thread_dbP.h
index 580a70c471..712fa3aeb6 100644
--- a/nptl_db/thread_dbP.h
+++ b/nptl_db/thread_dbP.h
@@ -108,6 +108,8 @@ struct td_thragent
# undef DB_SYMBOL
# undef DB_VARIABLE
+ psaddr_t ta_addr__rtld_global;
+
/* The method of locating a thread's th_unique value. */
enum
{
--
2.31.1
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