[PowerPC] Consolidate wordsize getter between native and gdbserver

This patch moves the native target wordsize getter for ppc linux to
nat/ so that it can be used to simplify ppc_arch_setup in
gdbserver. The ptrace call used to get MSR for this is ultimately the
same as before, but it is no longer necessary to create a temporary
regcache to call fetch_inferior_registers.

gdb/ChangeLog:
2018-05-22  Pedro Franco de Carvalho  <pedromfc@linux.vnet.ibm.com>

	* configure.nat <linux powerpc>: Add ppc-linux.o to NATDEPFILES.
	* ppc-linux-nat.c (ppc_linux_target_wordsize): Move to
	nat/ppc-linux.c.
	(ppc_linux_nat_target::auxv_parse): Get thread id tid. Call
	ppc_linux_target_wordsize with tid.
	(ppc_linux_nat_target::read_description): Call ppc_linux_target
	wordsize with tid.
	* nat/ppc-linux.c: Include nat/gdb_ptrace.h.
	(ppc64_64bit_inferior_p): Add static and inline specifiers.
	(ppc_linux_target_wordsize): Move here from ppc-linux-nat.c. Add
	tid parameter. Remove static specifier.
	* nat/ppc-linux.h (ppc64_64bit_inferior_p): Remove declaration.
	(ppc_linux_target_wordsize): New declaration.

gdb/gdbserver/ChangeLog:
2018-05-22  Pedro Franco de Carvalho  <pedromfc@linux.vnet.ibm.com>

	* linux-ppc-low.c (ppc_arch_setup): Remove code for getting the
	wordsize of the inferior. Call ppc_linux_target_wordsize.

7 files changed, 57 insertions, 57 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7492083f..7e9b9b2 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,21 @@
 2018-05-22  Pedro Franco de Carvalho  <pedromfc@linux.vnet.ibm.com>
 
+	* configure.nat <linux powerpc>: Add ppc-linux.o to NATDEPFILES.
+	* ppc-linux-nat.c (ppc_linux_target_wordsize): Move to
+	nat/ppc-linux.c.
+	(ppc_linux_nat_target::auxv_parse): Get thread id tid. Call
+	ppc_linux_target_wordsize with tid.
+	(ppc_linux_nat_target::read_description): Call ppc_linux_target
+	wordsize with tid.
+	* nat/ppc-linux.c: Include nat/gdb_ptrace.h.
+	(ppc64_64bit_inferior_p): Add static and inline specifiers.
+	(ppc_linux_target_wordsize): Move here from ppc-linux-nat.c. Add
+	tid parameter. Remove static specifier.
+	* nat/ppc-linux.h (ppc64_64bit_inferior_p): Remove declaration.
+	(ppc_linux_target_wordsize): New declaration.
+
+2018-05-22  Pedro Franco de Carvalho  <pedromfc@linux.vnet.ibm.com>
+
 	* arch/ppc-linux-common.c: New file.
 	* arch/ppc-linux-common.h: New file.
 	* arch/ppc-linux-tdesc.h: New file.
diff --git a/gdb/configure.nat b/gdb/configure.nat
index 6b0f44f..bcaeaf4 100644
--- a/gdb/configure.nat
+++ b/gdb/configure.nat
@@ -264,7 +264,7 @@ case ${gdb_host} in
 		;;
 	    powerpc)
 		# Host: PowerPC, running Linux
-		NATDEPFILES="${NATDEPFILES} ppc-linux-nat.o"
+		NATDEPFILES="${NATDEPFILES} ppc-linux-nat.o ppc-linux.o"
 		;;
 	    s390)
 		# Host: S390, running Linux
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 7d2281b..7d8b704 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,5 +1,10 @@
 2018-05-22  Pedro Franco de Carvalho  <pedromfc@linux.vnet.ibm.com>
 
+	* linux-ppc-low.c (ppc_arch_setup): Remove code for getting the
+	wordsize of the inferior. Call ppc_linux_target_wordsize.
+
+2018-05-22  Pedro Franco de Carvalho  <pedromfc@linux.vnet.ibm.com>
+
 	* configure.srv (srv_tgtobj): Add arch/ppc-linux-common.o.
 	* Makefile.in (SFILES): Add arch/ppc-linux-common.c.
 	* linux-ppc-tdesc.h: Rename to linux-ppc-tdesc-init.h.
diff --git a/gdb/gdbserver/linux-ppc-low.c b/gdb/gdbserver/linux-ppc-low.c
index 5361baf..30fcd41 100644
--- a/gdb/gdbserver/linux-ppc-low.c
+++ b/gdb/gdbserver/linux-ppc-low.c
@@ -620,36 +620,16 @@ ppc_arch_setup (void)
 {
   const struct target_desc *tdesc;
   struct ppc_linux_features features = ppc_linux_no_features;
+  int tid = lwpid_of (current_thread);
 
-  features.wordsize = 4;
-
-#ifdef __powerpc64__
-  long msr;
-  struct regcache *regcache;
-
-  /* On a 64-bit host, assume 64-bit inferior process with no
-     AltiVec registers.  Reset ppc_hwcap to ensure that the
-     collect_register call below does not fail.  */
-  tdesc = tdesc_powerpc_64l;
-  current_process ()->tdesc = tdesc;
-  ppc_hwcap = 0;
-
-  regcache = new_register_cache (tdesc);
-  fetch_inferior_registers (regcache, find_regno (tdesc, "msr"));
-  collect_register_by_name (regcache, "msr", &msr);
-  free_register_cache (regcache);
-  if (ppc64_64bit_inferior_p (msr))
-    {
-      features.wordsize = 8;
-    }
-#endif
+  features.wordsize = ppc_linux_target_wordsize (tid);
 
   if (features.wordsize == 4)
-    {
-      /* OK, we have a 32-bit inferior.  */
       tdesc = tdesc_powerpc_32l;
-      current_process ()->tdesc = tdesc;
-    }
+  else
+      tdesc = tdesc_powerpc_64l;
+
+  current_process ()->tdesc = tdesc;
 
   /* The value of current_process ()->tdesc needs to be set for this
      call.  */
diff --git a/gdb/nat/ppc-linux.c b/gdb/nat/ppc-linux.c
index 7ab6551..1796ceb 100644
--- a/gdb/nat/ppc-linux.c
+++ b/gdb/nat/ppc-linux.c
@@ -17,6 +17,7 @@
 
 #include "common-defs.h"
 #include "ppc-linux.h"
+#include "nat/gdb_ptrace.h"
 #include <elf.h>
 
 #ifdef HAVE_GETAUXVAL
@@ -53,7 +54,7 @@ ppc64_host_hwcap (unsigned long *valp)
 #endif /* HAVE_GETAUXVAL */
 }
 
-int
+static inline int
 ppc64_64bit_inferior_p (long msr)
 {
   unsigned long ppc_host_hwcap = 0;
@@ -73,3 +74,22 @@ ppc64_64bit_inferior_p (long msr)
 }
 
 #endif
+
+int
+ppc_linux_target_wordsize (int tid)
+{
+  int wordsize = 4;
+
+  /* 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__
+  long msr;
+
+  errno = 0;
+  msr = (long) ptrace (PTRACE_PEEKUSER, tid, PT_MSR * 8, 0);
+  if (errno == 0 && ppc64_64bit_inferior_p (msr))
+    wordsize = 8;
+#endif
+
+  return wordsize;
+}
diff --git a/gdb/nat/ppc-linux.h b/gdb/nat/ppc-linux.h
index 76a5d18..3d4d4fd 100644
--- a/gdb/nat/ppc-linux.h
+++ b/gdb/nat/ppc-linux.h
@@ -82,10 +82,7 @@
 #define PTRACE_SETEVRREGS 21
 #endif
 
-#ifdef __powerpc64__
-/* Return whether the inferior is 64bit or not by checking certain bit
-   in MSR.  */
-int ppc64_64bit_inferior_p (long msr);
-#endif
+/* Return the wordsize of the target, either 4 or 8 bytes.  */
+int ppc_linux_target_wordsize (int tid);
 
 #endif
diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index e49a482..7e96032 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -2368,35 +2368,17 @@ fill_fpregset (const struct regcache *regcache,
 			fpregsetp, sizeof (*fpregsetp));
 }
 
-static int
-ppc_linux_target_wordsize (void)
+int
+ppc_linux_nat_target::auxv_parse (gdb_byte **readptr,
+				  gdb_byte *endptr, CORE_ADDR *typep,
+				  CORE_ADDR *valp)
 {
-  int wordsize = 4;
-
-  /* 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__
-  long msr;
-
   int tid = ptid_get_lwp (inferior_ptid);
   if (tid == 0)
     tid = ptid_get_pid (inferior_ptid);
 
-  errno = 0;
-  msr = (long) ptrace (PTRACE_PEEKUSER, tid, PT_MSR * 8, 0);
-  if (errno == 0 && ppc64_64bit_inferior_p (msr))
-    wordsize = 8;
-#endif
-
-  return wordsize;
-}
+  int sizeof_auxv_field = ppc_linux_target_wordsize (tid);
 
-int
-ppc_linux_nat_target::auxv_parse (gdb_byte **readptr,
-				  gdb_byte *endptr, CORE_ADDR *typep,
-				  CORE_ADDR *valp)
-{
-  int sizeof_auxv_field = ppc_linux_target_wordsize ();
   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
   gdb_byte *ptr = *readptr;
 
@@ -2437,7 +2419,7 @@ ppc_linux_nat_target::read_description ()
 
   struct ppc_linux_features features = ppc_linux_no_features;
 
-  features.wordsize = ppc_linux_target_wordsize ();
+  features.wordsize = ppc_linux_target_wordsize (tid);
 
   unsigned long hwcap = ppc_linux_get_hwcap ();