[PowerPC] Add support for TAR

This patch adds support for the Target Address Register for powerpc
linux native and core file targets, and in the powerpc linux server
stub.

gdb/ChangeLog:
2018-10-26  Edjunior Barbosa Machado  <emachado@linux.vnet.ibm.com>
	    Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>

	* arch/ppc-linux-tdesc.h (tdesc_powerpc_isa207_vsx32l)
	(tdesc_powerpc_isa207_vsx64l): Declare.
	* arch/ppc-linux-common.h (PPC_LINUX_SIZEOF_TARREGSET): Define.
	(struct ppc_linux_features) <isa207>: New field.
	(ppc_linux_no_features): Add initializer for isa207 field.
	* arch/ppc-linux-common.c (ppc_linux_match_description): Return
	new tdescs.
	* nat/ppc-linux.h (PPC_FEATURE2_ARCH_2_07, PPC_FEATURE2_TAR)
	(NT_PPC_TAR): Define if not already defined.
	* features/Makefile (WHICH): Add rs6000/powerpc-isa207-vsx32l and
	rs6000/powerpc-isa207-vsx64l.
	(XMLTOC): Add rs6000/powerpc-isa207-vsx32l.xml and
	rs6000/powerpc-isa207-vsx64l.xml.
	* features/rs6000/power-tar.xml: New file.
	* features/rs6000/powerpc-isa207-vsx32l.xml: New file.
	* features/rs6000/powerpc-isa207-vsx64l.xml: New file.
	* features/rs6000/powerpc-isa207-vsx32l.c: Generate.
	* features/rs6000/powerpc-isa207-vsx64l.c: Generate.
	* regformats/rs6000/powerpc-isa207-vsx32l.dat: Generate.
	* regformats/rs6000/powerpc-isa207-vsx64l.dat: Generate.
	* ppc-linux-nat.c (fetch_register, fetch_ppc_registers): Call
	fetch_regset with the TAR regset.
	(store_register, store_ppc_registers): Call store_regset with the
	TAR regset.
	(ppc_linux_nat_target::read_description): Set isa207 field in the
	features struct if needed.
	* ppc-linux-tdep.c: Include
	features/rs6000/powerpc-isa207-vsx32l.c and
	features/rs6000/powerpc-isa207-vsx64l.c.
	(ppc32_regmap_tar, ppc32_linux_tarregset): New globals.
	(ppc_linux_iterate_over_regset_sections): Call back with the tar
	regset.
	(ppc_linux_core_read_description): Check if the tar section is
	present and set isa207 in the features struct.
	(_initialize_ppc_linux_tdep): Call
	initialize_tdesc_powerpc_isa207_vsx32l and
	initialize_tdesc_powerpc_isa207_vsx64l.
	* ppc-linux-tdep.h (ppc32_linux_tarregset): Declare.
	* ppc-tdep.h (gdbarch_tdep) <ppc_tar_regnum>: New field.
	(enum) <PPC_TAR_REGNUM>: New enum value.
	* rs6000-tdep.c (rs6000_gdbarch_init): Look for and validate tar
	feature.
	(ppc_process_record_op31): Record changes to TAR.

gdb/gdbserver/ChangeLog:
2018-10-26  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>

	* configure.srv (ipa_ppc_linux_regobj): Add
	powerpc-isa207-vsx64l-ipa.o and powerpc-isa207-vsx32l-ipa.o.
	(powerpc*-*-linux*): Add powerpc-isa207-vsx32l.o and
	powerpc-isa207-vsx64l.o to srv_regobj, add rs6000/power-tar.xml,
	rs6000/powerpc-isa207-vsx32l.xml, and
	rs6000/powerpc-isa207-vsx64l.xml to srv_xmlfiles.
	* linux-ppc-tdesc-init.h (enum ppc_linux_tdesc)
	<PPC_TDESC_ISA207_VSX>: New enum value.
	(init_registers_powerpc_isa207_vsx32l): Declare.
	(init_registers_powerpc_isa207_vsx64l): Declare.
	* linux-ppc-low.c (ppc_fill_tarregset): New function.
	(ppc_store_tarregset): New function.
	(ppc_regsets): Add entry for the TAR regset.
	(ppc_arch_setup): Set isa207 in features struct when needed.  Set
	size for the TAR regsets.
	(ppc_get_ipa_tdesc_idx): Return PPC_TDESC_ISA207_VSX.
	(initialize_low_arch): Call init_registers_powerpc_isa207_vsx32l
	and init_registers_powerpc_isa207_vsx64l.
	* linux-ppc-ipa.c (get_ipa_tdesc): Handle PPC_TDESC_ISA207_VSX.
	(initialize_low_tracepoint): Call
	init_registers_powerpc_isa207_vsx32l and
	init_registers_powerpc_isa207_vsx64l.

gdb/testsuite/ChangeLog:
2018-10-26  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>

	* gdb.arch/powerpc-tar.c: New file.
	* gdb.arch/powerpc-tar.exp: New file.

gdb/doc/ChangeLog:
2018-10-26  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>

	* gdb.texinfo (PowerPC Features): Describe new feature
	"org.gnu.gdb.power.tar".

2 files changed, 155 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.arch/powerpc-tar.c b/gdb/testsuite/gdb.arch/powerpc-tar.c
new file mode 100644
index 0000000..79c2528
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/powerpc-tar.c
@@ -0,0 +1,33 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   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/>.  */
+
+int main (void)
+{
+  void * target1 = &&target1_l;
+  void * target2 = &&target2_l;
+  asm volatile ("mtspr 815,%0" : : "r" (target1) : );
+
+  /* Branch always to TAR.  */
+  asm volatile ("bctar 20,0,0"); // marker
+
+ target2_l:
+  asm volatile ("nop"); // marker 2
+ target1_l:
+  asm volatile ("nop");
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/powerpc-tar.exp b/gdb/testsuite/gdb.arch/powerpc-tar.exp
new file mode 100644
index 0000000..98bdfd0
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/powerpc-tar.exp
@@ -0,0 +1,122 @@
+# Copyright (C) 2018 Free Software Foundation, Inc.
+
+# 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/>.
+
+# This file is part of the gdb testsuite.
+
+# Test access to special purpose register TAR (the Target Address
+# Register).  The test inferior writes to this register, we check that
+# GDB reads the same value, then write to the register the address of
+# another label.  We then let the inferior continue and execute a
+# branch to TAR and check that we stop at the address that we wrote to
+# register.
+
+if {![istarget "powerpc*-*-linux*"]} then {
+    verbose "Skipping PowerPC test for the TAR register."
+    return
+}
+
+standard_testfile .c
+
+if {[build_executable "compile" $binfile $srcfile {debug}] == -1} {
+    return -1
+}
+
+proc check_register_access { regname } {
+    global gdb_prompt
+
+    set test "$regname register access"
+    gdb_test_multiple "info reg $regname" "$test" {
+	-re "Invalid register.*\r\n$gdb_prompt $" {
+	    unsupported "$test"
+	    return 0
+	}
+	-re "\r\n$regname.*\r\n$gdb_prompt $" {
+	    pass "$test"
+	    return 1
+	}
+    }
+    return 0
+}
+
+proc tar_available {} {
+    global gdb_prompt
+    global inferior_exited_re
+
+    set test "TAR available to inferior"
+    gdb_test_multiple "continue" "" {
+	-re "Illegal instruction.*\r\n$gdb_prompt $" {
+	    unsupported "$test"
+	    return 0
+	}
+	-re "$inferior_exited_re normally.*$gdb_prompt $" {
+	    pass "$test"
+	    return 1
+	}
+    }
+    return 0
+}
+
+# Do one pass to check if TAR is usable, system
+# software can prevent it from being used.
+with_test_prefix "check TAR access" {
+    clean_restart $binfile
+
+    if ![runto_main] {
+	return
+    }
+
+    if {![check_register_access "tar"]} {
+	return
+    }
+
+    if {![tar_available]} {
+	return
+    }
+}
+
+# Now do the actual test
+clean_restart $binfile
+
+if ![runto_main] {
+    return
+}
+
+gdb_breakpoint [gdb_get_line_number "marker"]
+
+gdb_continue_to_breakpoint "continue to marker"
+
+set target1 [get_hexadecimal_valueof "target1" -1]
+set tar [get_hexadecimal_valueof "\$tar" -2]
+
+set test "TAR value from mtspr"
+
+if {${target1} == ${tar}} {
+    pass $test
+} else {
+    fail $test
+}
+
+set target2 [get_hexadecimal_valueof "target2" -1]
+
+if {$target2 == -1} {
+    fail "Could not get value of target2"
+    return
+}
+
+gdb_test_no_output "set \$tar = $target2" "set tar"
+
+gdb_breakpoint [gdb_get_line_number "marker 2"]
+
+gdb_continue_to_breakpoint "continue to new target address" ".*marker 2.*"