[rfc][1/2] add suport for 64-bit fpscr in powerpc linux native

[Thiago Jung Bauermann <bauerman@br.ibm.com>]

Hi,

The Power ISA 2.05 (implemented by Power6 and later) extended the FPSCR
from 32 bits to 64 bits. This patch makes GDB on native Linux display
the full extension of the register when it sees that it is running on
such a processor. I use the AUXV to detect the feature.

Ran the testsuite on ppc-linux and ppc64-linux, on a machine with 64-bit
FPSCR and also on a machine with a 32-bit FPSCR. No regressions found.
Ok?
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

:ADDPATCH powerpc:

2008-09-14  Thiago Jung Bauermann  <bauerman@br.ibm.com>

gdb/
	* ppc-linux-nat.c (ppc_register_u_addr): Add special case to return
	offset for full 64-bit slot of FPSCR when in 32-bits.
	(ppc_linux_read_description): Return target description with 64-bit
	FPSCR when inferior is running on an ISA 2.05 or later processor.
	* ppc-linux-tdep.c (_initialize_ppc_linux_tdep): Call
	initialize_tdec_powerpc_isa205_32l,
	initialize_tdec_powerpc_isa205_altivec32l,
	initialize_tdec_powerpc_isa205_vsx32l,
	initialize_tdec_powerpc_isa205_64l,
	initialize_tdec_powerpc_isa205_altivec64l and
	initialize_tdec_powerpc_isa205_vsx64l.
	* ppc-linux-tdep.h: Add external declaration for
	tdesc_powerpc_isa205_32l, tdesc_powerpc_isa205_altivec32l,
	tdesc_powerpc_isa205_vsx32l, tdesc_powerpc_isa205_64l,
	tdesc_powerpc_isa205_altivec64l and tdesc_powerpc_isa205_vsx64l.
	* features/rs600/powerpc-fpu-isa205.xml: New file.
	* features/rs600/powerpc-isa205-32l.xml: New file.
	* features/rs600/powerpc-isa205-64l.xml: New file.
	* features/rs600/powerpc-isa205-altivec32l.xml: New file.
	* features/rs600/powerpc-isa205-altivec64l.xml: New file.
	* features/rs600/powerpc-isa205-vsx32l.xml: New file.
	* features/rs600/powerpc-isa205-vsx64l.xml: New file.
	* features/rs600/powerpc-isa205-32l.c: Generate.
	* features/rs600/powerpc-isa205-64l.c: Generate.
	* features/rs600/powerpc-isa205-altivec32l.c: Generate.
	* features/rs600/powerpc-isa205-altivec64l.c: Generate.
	* features/rs600/powerpc-isa205-vsx32l.c: Generate.
	* features/rs600/powerpc-isa205-vsx64l.c: Generate.

gdb/testsuite/

	* gdb.arch/ppc-dfp.exp: New file.
	* gdb.arch/ppc-dfp.c: New file.

Index: gdb.git/gdb/features/rs6000/power-fpu-isa205.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/power-fpu-isa205.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,44 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2007, 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.power.fpu">
+  <reg name="f0" bitsize="64" type="ieee_double" regnum="32"/>
+  <reg name="f1" bitsize="64" type="ieee_double"/>
+  <reg name="f2" bitsize="64" type="ieee_double"/>
+  <reg name="f3" bitsize="64" type="ieee_double"/>
+  <reg name="f4" bitsize="64" type="ieee_double"/>
+  <reg name="f5" bitsize="64" type="ieee_double"/>
+  <reg name="f6" bitsize="64" type="ieee_double"/>
+  <reg name="f7" bitsize="64" type="ieee_double"/>
+  <reg name="f8" bitsize="64" type="ieee_double"/>
+  <reg name="f9" bitsize="64" type="ieee_double"/>
+  <reg name="f10" bitsize="64" type="ieee_double"/>
+  <reg name="f11" bitsize="64" type="ieee_double"/>
+  <reg name="f12" bitsize="64" type="ieee_double"/>
+  <reg name="f13" bitsize="64" type="ieee_double"/>
+  <reg name="f14" bitsize="64" type="ieee_double"/>
+  <reg name="f15" bitsize="64" type="ieee_double"/>
+  <reg name="f16" bitsize="64" type="ieee_double"/>
+  <reg name="f17" bitsize="64" type="ieee_double"/>
+  <reg name="f18" bitsize="64" type="ieee_double"/>
+  <reg name="f19" bitsize="64" type="ieee_double"/>
+  <reg name="f20" bitsize="64" type="ieee_double"/>
+  <reg name="f21" bitsize="64" type="ieee_double"/>
+  <reg name="f22" bitsize="64" type="ieee_double"/>
+  <reg name="f23" bitsize="64" type="ieee_double"/>
+  <reg name="f24" bitsize="64" type="ieee_double"/>
+  <reg name="f25" bitsize="64" type="ieee_double"/>
+  <reg name="f26" bitsize="64" type="ieee_double"/>
+  <reg name="f27" bitsize="64" type="ieee_double"/>
+  <reg name="f28" bitsize="64" type="ieee_double"/>
+  <reg name="f29" bitsize="64" type="ieee_double"/>
+  <reg name="f30" bitsize="64" type="ieee_double"/>
+  <reg name="f31" bitsize="64" type="ieee_double"/>
+
+  <reg name="fpscr" bitsize="64" group="float" regnum="70"/>
+</feature>
Index: gdb.git/gdb/features/rs6000/powerpc-isa205-32l.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/powerpc-isa205-32l.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!-- PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
+     view of the PowerPC.  Includes Linux-only special "registers".  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>powerpc:common</architecture>
+  <xi:include href="power-core.xml"/>
+  <xi:include href="power-fpu-isa205.xml"/>
+  <xi:include href="power-linux.xml"/>
+</target>
Index: gdb.git/gdb/features/rs6000/powerpc-isa205-64l.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/powerpc-isa205-64l.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!-- PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
+     view of the PowerPC.  Includes Linux-only special "registers".  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>powerpc:common64</architecture>
+  <xi:include href="power64-core.xml"/>
+  <xi:include href="power-fpu-isa205.xml"/>
+  <xi:include href="power64-linux.xml"/>
+</target>
Index: gdb.git/gdb/features/rs6000/powerpc-isa205-altivec32l.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/powerpc-isa205-altivec32l.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!-- PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
+     view of the PowerPC.  Includes Linux-only special "registers" and AltiVec
+     vector registers.  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>powerpc:common</architecture>
+  <xi:include href="power-core.xml"/>
+  <xi:include href="power-fpu-isa205.xml"/>
+  <xi:include href="power-linux.xml"/>
+  <xi:include href="power-altivec.xml"/>
+</target>
Index: gdb.git/gdb/features/rs6000/powerpc-isa205-altivec64l.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/powerpc-isa205-altivec64l.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!-- PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
+     view of the PowerPC.  Includes Linux-only special "registers" and AltiVec
+     vector registers.   -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>powerpc:common64</architecture>
+  <xi:include href="power64-core.xml"/>
+  <xi:include href="power-fpu-isa205.xml"/>
+  <xi:include href="power64-linux.xml"/>
+  <xi:include href="power-altivec.xml"/>
+</target>
Index: gdb.git/gdb/features/rs6000/powerpc-isa205-vsx32l.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/powerpc-isa205-vsx32l.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,20 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!-- PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
+     view of the PowerPC.  Includes Linux-only special "registers", AltiVec
+     and VSX vector registers.  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>powerpc:common</architecture>
+  <xi:include href="power-core.xml"/>
+  <xi:include href="power-fpu-isa205.xml"/>
+  <xi:include href="power-linux.xml"/>
+  <xi:include href="power-altivec.xml"/>
+  <xi:include href="power-vsx.xml"/>
+</target>
Index: gdb.git/gdb/features/rs6000/powerpc-isa205-vsx64l.xml
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/features/rs6000/powerpc-isa205-vsx64l.xml	2008-09-14 20:58:22.000000000 -0300
@@ -0,0 +1,20 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!-- PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
+     view of the PowerPC.  Includes Linux-only special "registers", AltiVec
+     and VSX vector registers.   -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>powerpc:common64</architecture>
+  <xi:include href="power64-core.xml"/>
+  <xi:include href="power-fpu-isa205.xml"/>
+  <xi:include href="power64-linux.xml"/>
+  <xi:include href="power-altivec.xml"/>
+  <xi:include href="power-vsx.xml"/>
+</target>
Index: gdb.git/gdb/ppc-linux-nat.c
===================================================================
--- gdb.git.orig/gdb/ppc-linux-nat.c	2008-09-13 17:45:29.000000000 -0300
+++ gdb.git/gdb/ppc-linux-nat.c	2008-09-14 20:58:23.000000000 -0300
@@ -60,6 +60,10 @@
 #define PPC_FEATURE_BOOKE 0x00008000
 #endif
 
+#ifndef PPC_FEATURE_ARCH_2_05
+#define PPC_FEATURE_ARCH_2_05	0x00001000 /* ISA 2.05 */
+#endif
+
 /* Glibc's headers don't define PTRACE_GETVRREGS so we cannot use a
    configure time check.  Some older glibc's (for instance 2.2.1)
    don't have a specific powerpc version of ptrace.h, and fall back on
@@ -279,6 +283,12 @@ ppc_register_u_addr (struct gdbarch *gdb
 	 hence no adjustment is necessary.  Hack around this.  */
       if (wordsize == 8 && PT_FPSCR == (48 + 32 + 1))
 	u_addr = (48 + 32) * wordsize;
+      /* If the FPSCR is 64-bit wide, we need to fetch the whole 64-bit
+	 slot and not just its second word.  The PT_FPSCR supplied in a
+	 32-bit GDB compilation doesn't reflect this.  */
+      else if (wordsize == 4 && register_size (gdbarch, regno) == 8
+	       && PT_FPSCR == (48 + 2*32 + 1))
+	u_addr = (48 + 2*32) * wordsize;
       else
 	u_addr = PT_FPSCR * wordsize;
     }
@@ -1230,6 +1240,7 @@ ppc_linux_read_description (struct targe
 {
   int altivec = 0;
   int vsx = 0;
+  int isa205 = 0;
 
   int tid = TIDGET (inferior_ptid);
   if (tid == 0)
@@ -1274,6 +1285,9 @@ ppc_linux_read_description (struct targe
 	perror_with_name (_("Unable to fetch AltiVec registers"));
     }
 
+  if (ppc_linux_get_hwcap () & PPC_FEATURE_ARCH_2_05)
+    isa205 = 1;
+
   /* Check for 64-bit inferior process.  This is the case when the host is
      64-bit, and in addition the top bit of the MSR register is set.  */
 #ifdef __powerpc64__
@@ -1284,21 +1298,21 @@ ppc_linux_read_description (struct targe
     if (errno == 0 && msr < 0)
       {
 	if (vsx)
-	  return tdesc_powerpc_vsx64l;
+	  return isa205? tdesc_powerpc_isa205_vsx64l : tdesc_powerpc_vsx64l;
 	else if (altivec)
-	  return tdesc_powerpc_altivec64l;
+	  return isa205? tdesc_powerpc_isa205_altivec64l : tdesc_powerpc_altivec64l;
 
-	return tdesc_powerpc_64l;
+	return isa205? tdesc_powerpc_isa205_64l : tdesc_powerpc_64l;
       }
   }
 #endif
 
   if (vsx)
-    return tdesc_powerpc_vsx32l;
+    return isa205? tdesc_powerpc_isa205_vsx32l : tdesc_powerpc_vsx32l;
   else if (altivec)
-    return tdesc_powerpc_altivec32l;
+    return isa205? tdesc_powerpc_isa205_altivec32l : tdesc_powerpc_altivec32l;
 
-  return tdesc_powerpc_32l;
+  return isa205? tdesc_powerpc_isa205_32l : tdesc_powerpc_32l;
 }
 
 void _initialize_ppc_linux_nat (void);
Index: gdb.git/gdb/ppc-linux-tdep.c
===================================================================
--- gdb.git.orig/gdb/ppc-linux-tdep.c	2008-09-13 17:45:29.000000000 -0300
+++ gdb.git/gdb/ppc-linux-tdep.c	2008-09-14 20:58:23.000000000 -0300
@@ -42,9 +42,15 @@
 #include "features/rs6000/powerpc-32l.c"
 #include "features/rs6000/powerpc-altivec32l.c"
 #include "features/rs6000/powerpc-vsx32l.c"
+#include "features/rs6000/powerpc-isa205-32l.c"
+#include "features/rs6000/powerpc-isa205-altivec32l.c"
+#include "features/rs6000/powerpc-isa205-vsx32l.c"
 #include "features/rs6000/powerpc-64l.c"
 #include "features/rs6000/powerpc-altivec64l.c"
 #include "features/rs6000/powerpc-vsx64l.c"
+#include "features/rs6000/powerpc-isa205-64l.c"
+#include "features/rs6000/powerpc-isa205-altivec64l.c"
+#include "features/rs6000/powerpc-isa205-vsx64l.c"
 #include "features/rs6000/powerpc-e500l.c"
 
 
@@ -1170,8 +1176,14 @@ _initialize_ppc_linux_tdep (void)
   initialize_tdesc_powerpc_32l ();
   initialize_tdesc_powerpc_altivec32l ();
   initialize_tdesc_powerpc_vsx32l ();
+  initialize_tdesc_powerpc_isa205_32l ();
+  initialize_tdesc_powerpc_isa205_altivec32l ();
+  initialize_tdesc_powerpc_isa205_vsx32l ();
   initialize_tdesc_powerpc_64l ();
   initialize_tdesc_powerpc_altivec64l ();
   initialize_tdesc_powerpc_vsx64l ();
+  initialize_tdesc_powerpc_isa205_64l ();
+  initialize_tdesc_powerpc_isa205_altivec64l ();
+  initialize_tdesc_powerpc_isa205_vsx64l ();
   initialize_tdesc_powerpc_e500l ();
 }
Index: gdb.git/gdb/ppc-linux-tdep.h
===================================================================
--- gdb.git.orig/gdb/ppc-linux-tdep.h	2008-09-13 17:45:29.000000000 -0300
+++ gdb.git/gdb/ppc-linux-tdep.h	2008-09-14 20:58:23.000000000 -0300
@@ -42,9 +42,15 @@ int ppc_linux_trap_reg_p (struct gdbarch
 extern struct target_desc *tdesc_powerpc_32l;
 extern struct target_desc *tdesc_powerpc_altivec32l;
 extern struct target_desc *tdesc_powerpc_vsx32l;
+extern struct target_desc *tdesc_powerpc_isa205_32l;
+extern struct target_desc *tdesc_powerpc_isa205_altivec32l;
+extern struct target_desc *tdesc_powerpc_isa205_vsx32l;
 extern struct target_desc *tdesc_powerpc_e500l;
 extern struct target_desc *tdesc_powerpc_64l;
 extern struct target_desc *tdesc_powerpc_altivec64l;
 extern struct target_desc *tdesc_powerpc_vsx64l;
+extern struct target_desc *tdesc_powerpc_isa205_64l;
+extern struct target_desc *tdesc_powerpc_isa205_altivec64l;
+extern struct target_desc *tdesc_powerpc_isa205_vsx64l;
 
 #endif /* PPC_LINUX_TDEP_H */
Index: gdb.git/gdb/testsuite/gdb.arch/ppc-dfp.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/testsuite/gdb.arch/ppc-dfp.c	2008-09-14 20:58:23.000000000 -0300
@@ -0,0 +1,46 @@
+/* Copyright 2008 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/>.  */
+
+#include <elf.h>
+
+#ifdef __powerpc64__
+typedef Elf64_auxv_t auxv_t;
+#else
+typedef Elf32_auxv_t auxv_t;
+#endif
+
+#ifndef PPC_FEATURE_HAS_DFP
+#define PPC_FEATURE_HAS_DFP	0x00000400
+#endif
+
+int
+main (int argc, char *argv[], char *envp[], auxv_t auxv[])
+{
+  int i;
+
+  for (i = 0; auxv[i].a_type != AT_NULL; i++)
+    if (auxv[i].a_type == AT_HWCAP) {
+      if (!(auxv[i].a_un.a_val & PPC_FEATURE_HAS_DFP))
+	return 1;
+
+      break;
+    }
+
+  asm ("mtfsfi 7, 5, 1\n");  /* Set DFP rounding mode.  */
+
+  return 0;
+}
Index: gdb.git/gdb/testsuite/gdb.arch/ppc-dfp.exp
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb.git/gdb/testsuite/gdb.arch/ppc-dfp.exp	2008-09-14 20:58:39.000000000 -0300
@@ -0,0 +1,82 @@
+# Copyright (C) 2008 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/>.
+#
+# Please email any bugs, comments, and/or additions to this file to:
+# bug-gdb@prep.ai.mit.edu
+#
+
+# Tests for Powerpc Decimal Floating Point registers setting and fetching
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+if ![istarget "powerpc*"] then {
+    verbose "Skipping powerpc decimal floating point register tests."
+    return
+}
+
+set testfile "ppc-dfp"
+set binfile ${objdir}/${subdir}/${testfile}
+set srcfile ${testfile}.c
+
+if [get_compiler_info $binfile] {
+    warning "get_compiler failed"
+    return -1
+}
+
+if ![test_compiler_info gcc*] {
+    # We use GCC's extended asm syntax
+    warning "unknown compiler"
+    return -1
+}
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {quiet debug}] != "" } {
+    unsupported "This machine doesn't support Decimal Floating Point."
+    return -1
+}
+
+# Start with a fresh gdb.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+gdb_breakpoint [gdb_get_line_number "Set DFP rounding mode."]
+
+gdb_run_cmd
+
+# When the prompt comes back we'll be at the Set DFP rounding mode breakpoint.
+# Unless the program bails out after checking AT_HWCAP.
+gdb_expect {
+  -re "Program exited with code 01.\[\r\n\]+$gdb_prompt $" {
+    unsupported "This machine doesn't support Decimal Floating Point."
+    return -1
+  }
+
+  -re ".*$gdb_prompt $" {}
+}
+
+# First, verify if FPSCR is all zeroes.
+gdb_test "print \$fpscr" " = 0" "FPSCR is all zeroes"
+
+# Step over "set rounding mode" instruction.
+gdb_test "next" "" ""
+
+# Verify that the following bits are set (See Power ISA for details):
+#
+# 29:31 - DFP Rounding Control
+gdb_test "print/t \$fpscr" " = 10100000000000000000000000000000000" "FPSCR for round to nearest, ties toward zero rounding mode"