Use arm target description and regs_info for 32-bit file on aarch64 GDBserver

This patch teaches aarch64-linux GDBserver use 32-bit arm target
description and regs_info if the elf file is 32-bit.

gdb/gdbserver:

2015-08-04  Yao Qi  <yao.qi@linaro.org>

	* configure.srv (case aarch64*-*-linux*): Append arm-with-neon.o
	to srv_regobj and append arm-core.xml arm-vfpv3.xml and
	arm-with-neon.xml to srv_xmlfiles.
	* linux-aarch64-low.c: Include linux-aarch32-low.h.
	(is_64bit_tdesc): New function.
	(aarch64_linux_read_description): New function.
	(aarch64_arch_setup): Call aarch64_linux_read_description.
	(regs_info): Rename to regs_info_aarch64.
	(aarch64_regs_info): Return right regs_info.
	(initialize_low_arch): Call initialize_low_arch_aarch32.

gdb/gdbserver/ChangeLog

@@ -1,3 +1,16 @@
+2015-08-04  Yao Qi  <yao.qi@linaro.org>
+
+	* configure.srv (case aarch64*-*-linux*): Append arm-with-neon.o
+	to srv_regobj and append arm-core.xml arm-vfpv3.xml and
+	arm-with-neon.xml to srv_xmlfiles.
+	* linux-aarch64-low.c: Include linux-aarch32-low.h.
+	(is_64bit_tdesc): New function.
+	(aarch64_linux_read_description): New function.
+	(aarch64_arch_setup): Call aarch64_linux_read_description.
+	(regs_info): Rename to regs_info_aarch64.
+	(aarch64_regs_info): Return right regs_info.
+	(initialize_low_arch): Call initialize_low_arch_aarch32.
+
 2015-08-04  Yao Qi  <yao.qi@linaro.org>
 
 	* configure.srv (srv_tgtobj): Add linux-aarch32-low.o.

gdb/gdbserver/configure.srv

@@ -49,11 +49,15 @@ srv_linux_obj="linux-low.o linux-osdata.o linux-procfs.o linux-ptrace.o linux-wa
 case "${target}" in
   aarch64*-*-linux*)
 			srv_regobj="aarch64.o"
+			srv_regobj="${srv_regobj} arm-with-neon.o"
 			srv_tgtobj="linux-aarch64-low.o aarch64-linux-hw-point.o"
+			srv_tgtobj="$srv_tgtobj linux-aarch32-low.o"
 			srv_tgtobj="${srv_tgtobj} $srv_linux_obj"
 			srv_xmlfiles="aarch64.xml"
 			srv_xmlfiles="${srv_xmlfiles} aarch64-core.xml"
 			srv_xmlfiles="${srv_xmlfiles} aarch64-fpu.xml"
+			srv_xmlfiles="${srv_xmlfiles} arm-core.xml arm-vfpv3.xml"
+			srv_xmlfiles="${srv_xmlfiles} arm-with-neon.xml"
 			srv_linux_regsets=yes
 			srv_linux_thread_db=yes
 			;;

gdb/gdbserver/linux-aarch64-low.c

@@ -22,6 +22,7 @@
 #include "server.h"
 #include "linux-low.h"
 #include "nat/aarch64-linux-hw-point.h"
+#include "linux-aarch32-low.h"
 #include "elf/common.h"
 
 #include <signal.h>
@@ -69,6 +70,16 @@ struct arch_process_info
   struct aarch64_debug_reg_state debug_reg_state;
 };
 
+/* Return true if the size of register 0 is 8 byte.  */
+
+static int
+is_64bit_tdesc (void)
+{
+  struct regcache *regcache = get_thread_regcache (current_thread, 0);
+
+  return register_size (regcache->tdesc, 0) == 8;
+}
+
 /* Implementation of linux_target_ops method "cannot_store_register".  */
 
 static int
@@ -582,12 +593,32 @@ aarch64_linux_prepare_to_resume (struct lwp_info *lwp)
     }
 }
 
+/* Return the right target description according to the ELF file of
+   current thread.  */
+
+static const struct target_desc *
+aarch64_linux_read_description (void)
+{
+  unsigned int machine;
+  int is_elf64;
+  int tid;
+
+  tid = lwpid_of (current_thread);
+
+  is_elf64 = linux_pid_exe_is_elf_64_file (tid, &machine);
+
+  if (is_elf64)
+    return tdesc_aarch64;
+  else
+    return tdesc_arm_with_neon;
+}
+
 /* Implementation of linux_target_ops method "arch_setup".  */
 
 static void
 aarch64_arch_setup (void)
 {
-  current_process ()->tdesc = tdesc_aarch64;
+  current_process ()->tdesc = aarch64_linux_read_description ();
 
   aarch64_linux_get_debug_reg_capacity (lwpid_of (current_thread));
 }
@@ -611,7 +642,7 @@ static struct regsets_info aarch64_regsets_info =
     NULL, /* disabled_regsets */
   };
 
-static struct regs_info regs_info =
+static struct regs_info regs_info_aarch64 =
   {
     NULL, /* regset_bitmap */
     NULL, /* usrregs */
@@ -623,7 +654,10 @@ static struct regs_info regs_info =
 static const struct regs_info *
 aarch64_regs_info (void)
 {
-  return &regs_info;
+  if (is_64bit_tdesc ())
+    return &regs_info_aarch64;
+  else
+    return &regs_info_aarch32;
 }
 
 /* Implementation of linux_target_ops method "supports_tracepoints".  */
@@ -682,5 +716,7 @@ initialize_low_arch (void)
 {
   init_registers_aarch64 ();
 
+  initialize_low_arch_aarch32 ();
+
   initialize_regsets_info (&aarch64_regsets_info);
 }