[PATCH v2 2/8] [PowerPC] Consolidate wordsize getter between native and gdbserver

[Pedro Franco de Carvalho <pedromfc@linux.vnet.ibm.com>]

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:
yyyy-mm-dd  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:
yyyy-mm-dd  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.
---
 gdb/configure.nat             |  2 +-
 gdb/gdbserver/linux-ppc-low.c | 32 ++++++--------------------------
 gdb/nat/ppc-linux.c           | 22 +++++++++++++++++++++-
 gdb/nat/ppc-linux.h           |  7 ++-----
 gdb/ppc-linux-nat.c           | 32 +++++++-------------------------
 5 files changed, 37 insertions(+), 58 deletions(-)

diff --git a/gdb/configure.nat b/gdb/configure.nat
index 6b0f44fede..bcaeaf4583 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/linux-ppc-low.c b/gdb/gdbserver/linux-ppc-low.c
index 5361baf72a..30fcd4115a 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 7ab6551316..1796ceb751 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 76a5d181df..3d4d4fdc56 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 e49a482c09..7e96032d4c 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 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
 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 ();
+  int tid = ptid_get_lwp (inferior_ptid);
+  if (tid == 0)
+    tid = ptid_get_pid (inferior_ptid);
+
+  int sizeof_auxv_field = ppc_linux_target_wordsize (tid);
+
   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 ();
 
-- 
2.13.6