TLS access support in multiarch Linux GNU GDB

TLS variable was not propagating from core dump file to
GDB and this patch implements that behavior for multiarch GDB.
This  approach includes linux-thread-db.c to be compiled
for multiarch GDB, where appropriate functions for
getting TLS addresses are used. If the program being debugged
is built for host architecture, we keep the old way
of calculating TLS. For target architectures modified
libthread_db functions (td_ta_new(), td_thr_tls_get_addr(),
td_thr_tlsbase()) are used, which can work with any version of glibc.
Also, additional functions are copied from glibc
in order to satisfy missing dependencies.

Similar to native debugging,  host libthread_db.so
should be loaded into multiarch GDB. It should be
the same version of the library which is used
for getting core dump file.  This is needed in order
to initialize necessary thread data in libthread_db.so.

        * Makefile.in(INTERNAL_CCFLAGS): Add CFLAGS for glibc-dep/.
        (CCOMPILE): Force glibc-dep/ to be compiled with gcc.
        * gdb/config/glibc.mh(GLIBCFILES): Define object files that
        will be generated in order to read TLS with GDB Multiarch.
        [DCROSS_GDB]: Define if it's GDB Multiarch.
        * gdb/configure.ac(cross_makefile_frag): Add GLIBCFILES in
        order to generate Makefile for cross platforms to read TLS.
        * gdb/configure: Regenerate.
        * gdb/gdb_proc_service.h: Add necessary code in order to
        compile glibc-dep/ with GCC.
        * gdb/gdbarch.c: Likewise.
        * gdb/glibc-dep/README.txt: Brief explanation of glibc-dep/.
        * gdb/glibc-dep/gdb_td_ta_new.c(init_target_dep_constants): New
        function.
        (gdb_td_ta_new): Get current version of GLIBC from coredump file.
        * gdb/glibc-dep/native-check.c(get_host_mach): New function.
        (native_check): Check if it is native architecture when using
        GDB Multiarch.
        * gdb/glibc-dep/db-symbols.h: Take necessary code from GLIBC
        in order to annul differences between GLIBC versions for reading
        TLS.
        * gdb/glibc-dep/nptl_db/fetch-value.c: Likewise.
        * gdb/glibc-dep/nptl_db/structs.def: Likewise.
        * gdb/glibc-dep/nptl_db/td_symbol_list.c: Likewise.
        * gdb/glibc-dep/nptl_db/td_ta_map_lwp2thr.c: Likewise.
        * gdb/glibc-dep/nptl_db/td_thr_tls_get_addr.c: Likewise.
        * gdb/glibc-dep/nptl_db/td_thr_tlsbase.c: Likewise. Modify in
        order to work with different versions of GLIBC.
        * gdb/glibc-dep/nptl_db/thread_dbP.h: Likewise.
        * gdb/glibc-dep/nptl_db/tls.h: Likewise.
        * gdb/gregset.h: Remove deprecated gregset_t but use
        elf_gregset_t.
        * gdb/linux-thread-db.c: (try_thread_db_load_1): Set up TLS
        functions from glibc-dep/.
        * gdb/nat/gdb_thread_db.h: (gdb_td_ta_new, gdb_td_thr_tlsbase)
        (gdb_td_thr_tls_get_addr, native_check): Declare TLS functions.

gdb/Makefile.in

@@ -727,6 +727,10 @@ ALL_TARGET_OBS = \
 @host_makefile_frag@
 # End of host-dependent makefile fragment
 
+# Cross fragment
+@cross_makefile_frag@
+# End of cross fragment
+
 FLAGS_TO_PASS = \
 	"prefix=$(prefix)" \
 	"exec_prefix=$(exec_prefix)" \
@@ -1008,7 +1012,7 @@ INFOFILES = gdb.info*
 # Makefile.in
 
 DEPFILES = $(TARGET_OBS) $(SER_HARDWIRE) $(NATDEPFILES) \
-	   $(REMOTE_OBS) $(SIM_OBS)
+	   $(REMOTE_OBS) $(SIM_OBS) $(GLIBCFILES)
 
 SOURCES = $(SFILES) $(ALLDEPFILES) $(YYFILES) $(CONFIG_SRCS)
 # Don't include YYFILES (*.c) because we already include *.y in SFILES,
@@ -2321,6 +2325,40 @@ arm-get-next-pcs.o: ${srcdir}/arch/arm-get-next-pcs.c
 	$(COMPILE) $(srcdir)/arch/arm-get-next-pcs.c
 	$(POSTCOMPILE)
 
+# gdb/glibc-dep/ dependencies
+#
+# Need to explicitly specify the compile rule as make will do nothing
+# or try to compile the object file into the sub-directory.
+
+td_ta_map_lwp2thr.o: $(srcdir)/glibc-dep/nptl_db/td_ta_map_lwp2thr.c
+	$(COMPILE) $(srcdir)/glibc-dep/nptl_db/td_ta_map_lwp2thr.c
+	$(POSTCOMPILE)
+
+td_symbol_list.o: $(srcdir)/glibc-dep/nptl_db/td_symbol_list.c
+	$(COMPILE) $(srcdir)/glibc-dep/nptl_db/td_symbol_list.c
+	$(POSTCOMPILE)
+
+fetch-value.o: $(srcdir)/glibc-dep/nptl_db/fetch-value.c
+	$(COMPILE) $(srcdir)/glibc-dep/nptl_db/fetch-value.c
+	$(POSTCOMPILE)
+
+gdb_td_ta_new.o: $(srcdir)/glibc-dep/gdb_td_ta_new.c
+	$(COMPILE) $(srcdir)/glibc-dep/gdb_td_ta_new.c
+	$(POSTCOMPILE)
+
+native_check.o: $(srcdir)/glibc-dep/native_check.c
+	$(COMPILE) $(srcdir)/glibc-dep/native_check.c
+	$(POSTCOMPILE)
+
+td_thr_tlsbase.o: $(srcdir)/glibc-dep/nptl_db/td_thr_tlsbase.c
+	$(COMPILE) $(srcdir)/glibc-dep/nptl_db/td_thr_tlsbase.c
+	$(POSTCOMPILE)
+
+td_thr_tls_get_addr.o: $(srcdir)/glibc-dep/nptl_db/td_thr_tls_get_addr.c
+	$(COMPILE) $(srcdir)/glibc-dep/nptl_db/td_thr_tls_get_addr.c
+	$(POSTCOMPILE)
+
+
 # gdb/nat/ dependencies
 #
 # Need to explicitly specify the compile rule as make will do nothing

gdb/config/glibc.mh

@@ -0,0 +1,6 @@
+# GLIBC fragment comes in here
+GLIBCFILES = td_symbol_list.o \
+	fetch-value.o gdb_td_ta_new.o \
+	td_thr_tlsbase.o td_thr_tls_get_addr.o \
+	td_ta_map_lwp2thr.o native_check.o
+INTERNAL_CFLAGS += -DCROSS_GDB

gdb/configure

@@ -804,6 +804,7 @@ PACKAGE_NAME
 PATH_SEPARATOR
 SHELL'
 ac_subst_files='host_makefile_frag'
+ac_subst_files2='cross_makefile_frag'
 ac_user_opts='
 enable_option_checking
 enable_maintainer_mode
@@ -2574,6 +2575,20 @@ _ASBOX
 
     if test -n "$ac_subst_files"; then
       cat <<\_ASBOX
+_ASBOX
+    echo
+    for ac_var in $ac_subst_vars
+    do
+      eval ac_val=\$$ac_var
+      case $ac_val in
+      *\'\''*) ac_val=`$as_echo "$ac_val" | sed "s/'\''/'\''\\\\\\\\'\'''\''/g"`;;
+      esac
+      $as_echo "$ac_var='\''$ac_val'\''"
+    done | sort
+    echo
+
+    if test -n "$ac_subst_files2"; then
+      cat <<\_ASBOX
 ## ------------------- ##
 ## File substitutions. ##
 ## ------------------- ##
@@ -2590,6 +2605,21 @@ _ASBOX
       echo
     fi
 
+    if test -s confdefs.h; then
+      cat <<\_ASBOX
+_ASBOX
+      echo
+      for ac_var in $ac_subst_files2
+      do
+	eval ac_val=\$$ac_var
+	case $ac_val in
+	*\'\''*) ac_val=`$as_echo "$ac_val" | sed "s/'\''/'\''\\\\\\\\'\'''\''/g"`;;
+	esac
+	$as_echo "$ac_var='\''$ac_val'\''"
+      done | sort
+      echo
+    fi
+
     if test -s confdefs.h; then
       cat <<\_ASBOX
 ## ----------- ##
@@ -15901,7 +15931,6 @@ fi
 
 
 
-
 if test "${gdb_native}" = "yes"; then
 # We pick this up from the host configuration file (.mh) because we
 # do not have a native configuration Makefile fragment.
@@ -15910,6 +15939,11 @@ s/NAT_FILE[ 	]*=[ 	]*\([^ 	]*\)/\1/p
 ' ${host_makefile_frag}`
 fi
 
+if test "${gdb_native}" = "no" || test "${enable_targets}" != ""; then
+  cross_makefile_frag=${srcdir}/config/glibc.mh
+else
+  cross_makefile_frag=/dev/null
+fi
 
 if test x"${gdb_osabi}" != x ; then
 
@@ -17403,6 +17437,7 @@ _ACEOF
   echo "cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1" &&
   echo 'cat >>"\$tmp/subs1.awk" <<\\_ACAWK &&' &&
   echo "$ac_subst_files" | sed 's/.*/F["&"]="$&"/' &&
+  echo "$ac_subst_files2" | sed 's/.*/F["&"]="$&"/' &&
   echo "_ACAWK" &&
   echo "_ACEOF"
 } >conf$$files.sh &&

gdb/gdb_proc_service.h

@@ -62,7 +62,7 @@ EXTERN_C_POP
 #include <sys/procfs.h>
 #endif
 
-EXTERN_C_PUSH
+//EXTERN_C_PUSH
 
 /* Functions in this interface return one of these status codes.  */
 typedef enum
@@ -159,7 +159,7 @@ extern ps_err_e ps_lsetxregs (struct ps_prochandle *ph, lwpid_t lwpid,
 /* Log a message (sends to gdb_stderr).  */
 extern void ps_plog (const char *fmt, ...);
 
-EXTERN_C_POP
+//EXTERN_C_POP
 
 #endif /* HAVE_PROC_SERVICE_H */
 

gdb/glibc-dep/README.txt

@@ -0,0 +1,42 @@
+Files and functions taken from GLIBC source code (${glibc_src}/nptl_db/) necessary for getting
+TLS variables (from coredump file) when cross GDB using GLIBC version 2.22 and higher are stored into
+${gdb_src}/glibc-dep/nptl_db directory.
+
+gdb_td_ta_new() is stored into ${gdb_src}/glibc-dep/ because functionality of function (td_ta_new())
+from GLIBC source has changed in order to get current version of GLIBC from coredump file.
+
+gdb_td_thr_tlsbase is function taken from nptl_db/td_thr_tlsbase.c,
+which has modified in GLIBC 2.22 and higher, so all dependent files had to be included into GDB source.
+
+------------------------
+
+${gdb_src}/glibc-dep/nptl_db
+
+* thread_dbP.h
+Taken needed definitions and macros.
+
+* db-symbols.h
+Unmodified.
+
+* fetch-value.c
+Taken needed functions.
+
+* structs.def
+Unmodified.
+
+* td_symbol_list.c
+Taken necessary definitions and modified td_lookup function.
+
+* td_ta_map_lwp2thr.c
+Taken only __td_ta_lookup_th_unique function unmodified.
+
+* td_thr_tlsbase.c
+gdb_td_thr_tlsbase(), modified in order to work with all GLIBC versions.
+${gdb_src}/gdb/config/${arch}/tls.h depending on architecture got different
+values of TLS_TCB_AT_TP and TLS_DTV_AT_TP macros taken
+from ${glibc_src}/sysdeps/${arch}/nptl/tls.h.
+
+* td_thr_tls_get_addr.c
+Unmodified.
+
+-------------------------

gdb/glibc-dep/gdb_td_ta_new.c

@@ -0,0 +1,72 @@
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <version.h>
+
+#include "nptl_db/thread_dbP.h"
+#include "../nat/gdb_thread_db.h"
+#include "../../../bfd/bfd.h"
+#include "nptl_db/tls.h"
+
+static td_err_e
+init_target_dep_constants()
+{
+	struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
+	unsigned arch = bfdarch->arch;
+	switch(arch){
+		case bfd_arch_mips:
+			tls_tcb_at_tp = 0;
+			tls_dtv_at_tp = 1;
+			forced_dynamic_tls_offset = -2;
+			no_tls_offset = -1;
+			tcb_alignment = 16;
+			break;
+		case bfd_arch_arm:
+			tls_tcb_at_tp = 0;
+			tls_dtv_at_tp = 1;
+			forced_dynamic_tls_offset = -2;
+			no_tls_offset = -1;
+			tcb_alignment = 0; //set to zero because not in use for TLS_PRE_TCB_SIZE
+			break;
+		case bfd_arch_i386:
+			tls_tcb_at_tp = 1;
+			tls_dtv_at_tp = 0;
+			forced_dynamic_tls_offset = -1;
+			no_tls_offset = 0;
+			tcb_alignment = 0; //set to zero because not in use for TLS_PRE_TCB_SIZE
+			break;
+		case bfd_arch_powerpc:
+			tls_tcb_at_tp = 0;
+			tls_dtv_at_tp = 1;
+			forced_dynamic_tls_offset = -2;
+			no_tls_offset = -1;
+			tcb_alignment = 48;
+			break;
+		case bfd_arch_aarch64:
+			tls_tcb_at_tp = 0;
+			tls_dtv_at_tp = 1;
+			forced_dynamic_tls_offset = -1;
+			no_tls_offset = 0;
+			tcb_alignment = 0; //set to zero because not in use for TLS_PRE_TCB_SIZE
+			break;
+		default:
+			return TD_ERR;
+	}
+	return TD_OK;
+}
+
+
+td_err_e
+gdb_td_ta_new (struct ps_prochandle *ps, td_thragent_t **ta)
+{
+  psaddr_t versaddr;
+
+  /* Check whether the versions match.  */
+  if (td_lookup (ps, SYM_nptl_version, &versaddr) != PS_OK)
+    return TD_NOLIBTHREAD;
+  if (ps_pdread (ps, versaddr, versbuf, sizeof (versbuf)) != PS_OK)
+    return TD_ERR;
+  if(init_target_dep_constants() != TD_OK)
+	return TD_ERR;
+  return TD_OK;
+}

gdb/glibc-dep/native_check.c

@@ -0,0 +1,40 @@
+#include "native_check.h"
+#include <string.h>
+#include <stdio.h>
+#include "../config.h"
+#include "../../../bfd/bfd.h"
+#include <sys/utsname.h>
+
+unsigned get_host_mach(char *name_of_arch){
+	unsigned result;
+
+	if(strstr(name_of_arch, "x86_64") != NULL)
+		result = bfd_arch_i386;
+	else if(strstr(name_of_arch, "i386") != NULL)
+		result = bfd_arch_i386;
+	else if(strstr(name_of_arch, "mips") != NULL)
+		result = bfd_arch_mips;
+	else if(strstr(name_of_arch, "arm") != NULL)
+		result = bfd_arch_arm;
+	else if(strstr(name_of_arch, "powerpc") != NULL)
+		result = bfd_arch_powerpc;
+	else if(strstr(name_of_arch, "aarch64") != NULL)
+		result = bfd_arch_aarch64;
+	else
+		result = -1;
+
+	return result;
+}
+
+int native_check(unsigned bfd_arch){
+    struct utsname buf;
+    if(uname(&buf) == 0){
+    unsigned host_mach = get_host_mach(buf.machine);
+
+    if(host_mach == bfd_arch)
+        return 0; //zero if it's host
+    else
+        return 1;
+	}
+	return -1;
+}

gdb/glibc-dep/native_check.h

@@ -0,0 +1,2 @@
+unsigned get_host_mach(char *name_of_arch);
+int native_check(unsigned bfd_arch);

gdb/glibc-dep/nptl_db/db-symbols.h

@@ -0,0 +1,51 @@
+/* List of symbols in libpthread examined by libthread_db.
+   Copyright (C) 2009-2016 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
+   <http://www.gnu.org/licenses/>.  */
+
+#define DOT(x)  x   /* No prefix.  */
+
+#define STRINGIFY(name)   STRINGIFY_1(name)
+#define STRINGIFY_1(name) #name
+
+#define DB_STRUCT(type) \
+  DB_LOOKUP_NAME (SYM_SIZEOF_##type, _thread_db_sizeof_##type)
+#define DB_STRUCT_FIELD(type, field) \
+  DB_LOOKUP_NAME (SYM_##type##_FIELD_##field, _thread_db_##type##_##field)
+#define DB_SYMBOL(name) \
+  DB_LOOKUP_NAME (SYM_##name, name)
+#define DB_FUNCTION(name) \
+  DB_LOOKUP_NAME (SYM_##name, DOT (name))
+#define DB_VARIABLE(name) \
+  DB_LOOKUP_NAME (SYM_##name, name) \
+  DB_LOOKUP_NAME (SYM_DESC_##name, _thread_db_##name)
+
+# include "structs.def"
+
+# undef DB_STRUCT
+# undef DB_FUNCTION
+# undef DB_SYMBOL
+# undef DB_VARIABLE
+# undef DOT
+
+DB_LOOKUP_NAME_TH_UNIQUE (SYM_TH_UNIQUE_REGISTER64, _thread_db_register64)
+DB_LOOKUP_NAME_TH_UNIQUE (SYM_TH_UNIQUE_REGISTER32, _thread_db_register32)
+DB_LOOKUP_NAME_TH_UNIQUE (SYM_TH_UNIQUE_CONST_THREAD_AREA,
+        _thread_db_const_thread_area)
+DB_LOOKUP_NAME_TH_UNIQUE (SYM_TH_UNIQUE_REGISTER32_THREAD_AREA,
+        _thread_db_register32_thread_area)
+DB_LOOKUP_NAME_TH_UNIQUE (SYM_TH_UNIQUE_REGISTER64_THREAD_AREA,
+        _thread_db_register64_thread_area)