150 lines
5.9 KiB
Diff
150 lines
5.9 KiB
Diff
From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
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From: Kevin Buettner <kevinb@redhat.com>
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Date: Mon, 14 Jun 2021 19:20:07 -0700
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Subject: gdb-rhbz1971096-glibc2.34-2.patch
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;; Backport patch fixing gdb on glibc-2.34 machines w/ regard to
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;; libthread_db initialization.
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libthread_db initialization changes related to upcoming glibc-2.34
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This commit makes some adjustments to accomodate the upcoming
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glibc-2.34 release. Beginning with glibc-2.34, functionality formerly
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contained in libpthread has been moved to libc. For the time being,
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libpthread.so still exists in the file system, but it won't show up in
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ldd output and therefore won't be able to trigger initialization of
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libthread_db related code. E.g...
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Fedora 34 / glibc-2.33.9000:
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[kev@f34-2 gdb]$ ldd testsuite/outputs/gdb.threads/tls/tls
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linux-vdso.so.1 (0x00007ffcf94fa000)
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libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007ff0ba9af000)
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libm.so.6 => /lib64/libm.so.6 (0x00007ff0ba8d4000)
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libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007ff0ba8b9000)
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libc.so.6 => /lib64/libc.so.6 (0x00007ff0ba6c6000)
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/lib64/ld-linux-x86-64.so.2 (0x00007ff0babf0000)
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Fedora 34 / glibc-2.33:
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[kev@f34-1 gdb]$ ldd testsuite/outputs/gdb.threads/tls/tls
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linux-vdso.so.1 (0x00007fff32dc0000)
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libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f815f6de000)
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libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f815f4bf000)
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libm.so.6 => /lib64/libm.so.6 (0x00007f815f37b000)
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libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f815f360000)
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libc.so.6 => /lib64/libc.so.6 (0x00007f815f191000)
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/lib64/ld-linux-x86-64.so.2 (0x00007f815f721000)
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Note that libpthread is missing from the ldd output for the
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glibc-2.33.9000 machine.
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This means that (unless we happen to think of some entirely different
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mechanism), we'll now need to potentially match "libc" in addition to
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"libpthread" as libraries which might be thread libraries. This
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accounts for the change made in solib.c. Note that the new code
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attempts to match "/libc." via strstr(). That trailing dot (".")
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avoids inadvertently matching libraries such as libcrypt (and
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all the other many libraries which begin with "libc").
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To avoid attempts to load libthread_db when encountering older
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versions of libc, we now attempt to find "pthread_create" (which is a
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symbol that we'd expect to be in any pthread library) in the
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associated objfile. This accounts for the changes in
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linux-thread-db.c.
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I think that other small adjustments will need to be made elsewhere
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too. I've been working through regressions on my glibc-2.33.9000
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machine; I've fixed some fairly "obvious" changes in the testsuite
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(which are in other commits). For the rest, it's not yet clear to me
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whether the handful of remaining failures represent a problem in glibc
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or gdb. I'm still investigating, however, I'll note that these are
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problems that I only see on my glibc-2.33.9000 machine.
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gdb/ChangeLog:
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* solib.c (libpthread_name_p): Match "libc" in addition
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to "libpthread".
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* linux-thread-db.c (libpthread_objfile_p): New function.
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(libpthread_name_p): Adjust preexisting callers to use
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libpthread_objfile_p().
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diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
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--- a/gdb/linux-thread-db.c
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+++ b/gdb/linux-thread-db.c
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@@ -800,6 +800,24 @@ check_thread_db (struct thread_db_info *info, bool log_progress)
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return test_passed;
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}
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+/* Predicate which tests whether objfile OBJ refers to the library
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+ containing pthread related symbols. Historically, this library has
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+ been named in such a way that looking for "libpthread" in the name
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+ was sufficient to identify it. As of glibc-2.34, the C library
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+ (libc) contains the thread library symbols. Therefore we check
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+ that the name matches a possible thread library, but we also check
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+ that it contains at least one of the symbols (pthread_create) that
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+ we'd expect to find in the thread library. */
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+
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+static bool
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+libpthread_objfile_p (objfile *obj)
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+{
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+ return (libpthread_name_p (objfile_name (obj))
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+ && lookup_minimal_symbol ("pthread_create",
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+ NULL,
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+ obj).minsym != NULL);
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+}
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+
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/* Attempt to initialize dlopen()ed libthread_db, described by INFO.
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Return true on success.
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Failure could happen if libthread_db does not have symbols we expect,
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@@ -1072,7 +1090,7 @@ try_thread_db_load_from_pdir (const char *subdir)
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return false;
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for (objfile *obj : current_program_space->objfiles ())
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- if (libpthread_name_p (objfile_name (obj)))
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+ if (libpthread_objfile_p (obj))
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{
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if (try_thread_db_load_from_pdir_1 (obj, subdir))
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return true;
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@@ -1181,7 +1199,7 @@ static bool
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has_libpthread (void)
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{
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for (objfile *obj : current_program_space->objfiles ())
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- if (libpthread_name_p (objfile_name (obj)))
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+ if (libpthread_objfile_p (obj))
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return true;
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return false;
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@@ -1295,7 +1313,7 @@ thread_db_new_objfile (struct objfile *objfile)
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of the list of shared libraries to load, and in an app of several
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thousand shared libraries, this can otherwise be painful. */
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&& ((objfile->flags & OBJF_MAINLINE) != 0
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- || libpthread_name_p (objfile_name (objfile))))
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+ || libpthread_objfile_p (objfile)))
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check_for_thread_db ();
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}
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diff --git a/gdb/solib.c b/gdb/solib.c
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--- a/gdb/solib.c
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+++ b/gdb/solib.c
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@@ -906,12 +906,17 @@ Do you need \"set solib-search-path\" or \"set sysroot\"?"),
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Uses a fairly simplistic heuristic approach where we check
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the file name against "/libpthread". This can lead to false
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- positives, but this should be good enough in practice. */
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+ positives, but this should be good enough in practice.
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+
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+ As of glibc-2.34, functions formerly residing in libpthread have
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+ been moved to libc, so "/libc." needs to be checked too. (Matching
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+ the "." will avoid matching libraries such as libcrypt.) */
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bool
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libpthread_name_p (const char *name)
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{
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- return (strstr (name, "/libpthread") != NULL);
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+ return (strstr (name, "/libpthread") != NULL
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+ || strstr (name, "/libc.") != NULL );
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}
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/* Return non-zero if SO is the libpthread shared library. */
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