xtensa: implement NPTL helpers

These changes allow debugging multithreaded NPTL xtensa applications.

2015-08-20  Max Filippov  <jcmvbkbc@gmail.com>
gdb/gdbserver/
	* configure.srv (xtensa*-*-linux*): Add srv_linux_thread_db=yes.
	* linux-xtensa-low.c (arch/xtensa.h gdb_proc_service.h): New
	#includes.
	(ps_get_thread_area): New function.

2015-08-20  Max Filippov  <jcmvbkbc@gmail.com>
gdb/
	* arch/xtensa.h: New file.
	* xtensa-linux-nat.c (gdb_proc_service.h): New #include.
	(ps_get_thread_area): New function.
	* xtensa-linux-tdep.c (xtensa_linux_init_abi): Add call to
	set_gdbarch_fetch_tls_load_module_address to enable TLS support.
	* xtensa-tdep.c (osabi.h): New #include.
	(xtensa_gdbarch_init): Call gdbarch_init_osabi to register
	xtensa-specific hooks.
	* xtensa-tdep.h (struct xtensa_elf_gregset_t): Add threadptr
	member and move the structure to arch/xtensa.h.

9 files changed, 120 insertions, 22 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e7cd74c..0393652 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,16 @@
+2015-08-20  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* arch/xtensa.h: New file.
+	* xtensa-linux-nat.c (gdb_proc_service.h): New #include.
+	(ps_get_thread_area): New function.
+	* xtensa-linux-tdep.c (xtensa_linux_init_abi): Add call to
+	set_gdbarch_fetch_tls_load_module_address to enable TLS support.
+	* xtensa-tdep.c (osabi.h): New #include.
+	(xtensa_gdbarch_init): Call gdbarch_init_osabi to register
+	xtensa-specific hooks.
+	* xtensa-tdep.h (struct xtensa_elf_gregset_t): Add threadptr
+	member and move the structure to arch/xtensa.h.
+
 2015-08-21  Pedro Alves  <palves@redhat.com>
 
 	* remote.c (struct readahead_cache): New.
diff --git a/gdb/arch/xtensa.h b/gdb/arch/xtensa.h
new file mode 100644
index 0000000..6a78c96
--- /dev/null
+++ b/gdb/arch/xtensa.h
@@ -0,0 +1,46 @@
+/* Common Target-dependent code for the Xtensa port of GDB, the GNU debugger.
+
+   Copyright (C) 2003-2015 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef XTENSA_H
+#define XTENSA_H
+
+/* Xtensa ELF core file register set representation ('.reg' section).
+   Copied from target-side ELF header <xtensa/elf.h>.  */
+
+typedef uint32_t xtensa_elf_greg_t;
+
+typedef struct
+{
+  xtensa_elf_greg_t pc;
+  xtensa_elf_greg_t ps;
+  xtensa_elf_greg_t lbeg;
+  xtensa_elf_greg_t lend;
+  xtensa_elf_greg_t lcount;
+  xtensa_elf_greg_t sar;
+  xtensa_elf_greg_t windowstart;
+  xtensa_elf_greg_t windowbase;
+  xtensa_elf_greg_t threadptr;
+  xtensa_elf_greg_t reserved[7+48];
+  xtensa_elf_greg_t ar[64];
+} xtensa_elf_gregset_t;
+
+#define XTENSA_ELF_NGREG (sizeof (xtensa_elf_gregset_t) \
+			  / sizeof (xtensa_elf_greg_t))
+
+#endif
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index ef49749..10961b0 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,10 @@
+2015-08-20  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* configure.srv (xtensa*-*-linux*): Add srv_linux_thread_db=yes.
+	* linux-xtensa-low.c (arch/xtensa.h gdb_proc_service.h): New
+	#includes.
+	(ps_get_thread_area): New function.
+
 2015-08-19  Gary Benson  <gbenson@redhat.com>
 
 	* hostio.c (handle_pread): Do not attempt to read more data
diff --git a/gdb/gdbserver/configure.srv b/gdb/gdbserver/configure.srv
index 0b18d1d..320c26a 100644
--- a/gdb/gdbserver/configure.srv
+++ b/gdb/gdbserver/configure.srv
@@ -352,6 +352,7 @@ case "${target}" in
   xtensa*-*-linux*)	srv_regobj=reg-xtensa.o
 			srv_tgtobj="$srv_linux_obj linux-xtensa-low.o"
 			srv_linux_regsets=yes
+			srv_linux_thread_db=yes
 			;;
   tilegx-*-linux*)	srv_regobj=reg-tilegx.o
 			srv_regobj="${srv_regobj} reg-tilegx32.o"
diff --git a/gdb/gdbserver/linux-xtensa-low.c b/gdb/gdbserver/linux-xtensa-low.c
index 4daccee..debe467 100644
--- a/gdb/gdbserver/linux-xtensa-low.c
+++ b/gdb/gdbserver/linux-xtensa-low.c
@@ -26,6 +26,8 @@ extern const struct target_desc *tdesc_xtensa;
 
 #include <asm/ptrace.h>
 #include <xtensa-config.h>
+#include "arch/xtensa.h"
+#include "gdb_proc_service.h"
 
 #include "xtensa-xtregs.c"
 
@@ -179,6 +181,25 @@ xtensa_breakpoint_at (CORE_ADDR where)
 		  xtensa_breakpoint, xtensa_breakpoint_len) == 0;
 }
 
+/* Called by libthread_db.  */
+
+ps_err_e
+ps_get_thread_area (const struct ps_prochandle *ph,
+                    lwpid_t lwpid, int idx, void **base)
+{
+  xtensa_elf_gregset_t regs;
+
+  if (ptrace (PTRACE_GETREGS, lwpid, NULL, &regs) != 0)
+    return PS_ERR;
+
+  /* IDX is the bias from the thread pointer to the beginning of the
+     thread descriptor.  It has to be subtracted due to implementation
+     quirks in libthread_db.  */
+  *base = (void *) ((char *) regs.threadptr - idx);
+
+  return PS_OK;
+}
+
 static struct regsets_info xtensa_regsets_info =
   {
     xtensa_regsets, /* regsets */
diff --git a/gdb/xtensa-linux-nat.c b/gdb/xtensa-linux-nat.c
index 77ad3e0..5538d5b 100644
--- a/gdb/xtensa-linux-nat.c
+++ b/gdb/xtensa-linux-nat.c
@@ -37,6 +37,9 @@
 #include "gregset.h"
 #include "xtensa-tdep.h"
 
+/* Defines ps_err_e, struct ps_prochandle.  */
+#include "gdb_proc_service.h"
+
 /* Extended register set depends on hardware configs.
    Keeping these definitions separately allows to introduce
    hardware-specific overlays.  */
@@ -280,6 +283,25 @@ xtensa_linux_store_inferior_registers (struct target_ops *ops,
     store_xtregs (regcache, regnum);
 }
 
+/* Called by libthread_db.  */
+
+ps_err_e
+ps_get_thread_area (const struct ps_prochandle *ph,
+                    lwpid_t lwpid, int idx, void **base)
+{
+  xtensa_elf_gregset_t regs;
+
+  if (ptrace (PTRACE_GETREGS, lwpid, NULL, &regs) != 0)
+    return PS_ERR;
+
+  /* IDX is the bias from the thread pointer to the beginning of the
+     thread descriptor.  It has to be subtracted due to implementation
+     quirks in libthread_db.  */
+  *base = (void *) ((char *) regs.threadptr - idx);
+
+  return PS_OK;
+}
+
 void _initialize_xtensa_linux_nat (void);
 
 void
diff --git a/gdb/xtensa-linux-tdep.c b/gdb/xtensa-linux-tdep.c
index 61ea9b0..99e0d3e 100644
--- a/gdb/xtensa-linux-tdep.c
+++ b/gdb/xtensa-linux-tdep.c
@@ -106,6 +106,10 @@ xtensa_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 				      xtensa_linux_gdb_signal_from_target);
   set_gdbarch_gdb_signal_to_target (gdbarch,
 				    xtensa_linux_gdb_signal_to_target);
+
+  /* Enable TLS support.  */
+  set_gdbarch_fetch_tls_load_module_address (gdbarch,
+                                             svr4_fetch_objfile_link_map);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c
index 55e7d98..4b693ed 100644
--- a/gdb/xtensa-tdep.c
+++ b/gdb/xtensa-tdep.c
@@ -28,6 +28,7 @@
 #include "value.h"
 #include "dis-asm.h"
 #include "inferior.h"
+#include "osabi.h"
 #include "floatformat.h"
 #include "regcache.h"
 #include "reggroups.h"
@@ -3273,6 +3274,9 @@ xtensa_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   set_solib_svr4_fetch_link_map_offsets
     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 
+  /* Hook in the ABI-specific overrides, if they have been registered.  */
+  gdbarch_init_osabi (info, gdbarch);
+
   return gdbarch;
 }
 
diff --git a/gdb/xtensa-tdep.h b/gdb/xtensa-tdep.h
index caa2988..5b28cab 100644
--- a/gdb/xtensa-tdep.h
+++ b/gdb/xtensa-tdep.h
@@ -18,6 +18,8 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
+#include "arch/xtensa.h"
+
 /* XTENSA_TDEP_VERSION can/should be changed along with XTENSA_CONFIG_VERSION
    whenever the "tdep" structure changes in an incompatible way.  */
 
@@ -81,28 +83,6 @@ typedef enum
 } xtensa_target_flags_t;
 
 
-/* Xtensa ELF core file register set representation ('.reg' section).
-   Copied from target-side ELF header <xtensa/elf.h>.  */
-
-typedef uint32_t xtensa_elf_greg_t;
-
-typedef struct
-{
-  xtensa_elf_greg_t pc;
-  xtensa_elf_greg_t ps;
-  xtensa_elf_greg_t lbeg;
-  xtensa_elf_greg_t lend;
-  xtensa_elf_greg_t lcount;
-  xtensa_elf_greg_t sar;
-  xtensa_elf_greg_t windowstart;
-  xtensa_elf_greg_t windowbase;
-  xtensa_elf_greg_t reserved[8+48];
-  xtensa_elf_greg_t ar[64];
-} xtensa_elf_gregset_t;
-
-#define XTENSA_ELF_NGREG (sizeof (xtensa_elf_gregset_t) \
-			  / sizeof (xtensa_elf_greg_t))
-
 /*  Mask.  */
 
 typedef struct