Re: [PATCH] ppc64le/gdbserver: Fix ppc_collect/supply_ptrace_register() routines

[Edjunior Barbosa Machado <emachado at linux dot vnet dot ibm dot com>]

Thanks Sergio and Ulrich for the review. Here is the patch with the suggested
modifications.

Thanks and regards,
--
Edjunior

gdb/gdbserver/
2014-09-08  Edjunior Barbosa Machado  <emachado@linux.vnet.ibm.com>

	* linux-ppc-low.c (ppc_collect_ptrace_register): Adjust routine to take
	endianness into account.
	(ppc_supply_ptrace_register): Likewise.

---
 gdb/gdbserver/linux-ppc-low.c |   45 ++++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 9 deletions(-)

diff --git a/gdb/gdbserver/linux-ppc-low.c b/gdb/gdbserver/linux-ppc-low.c
index d743311..8fd4b38 100644
--- a/gdb/gdbserver/linux-ppc-low.c
+++ b/gdb/gdbserver/linux-ppc-low.c
@@ -202,25 +202,52 @@ ppc_cannot_fetch_register (int regno)
 static void
 ppc_collect_ptrace_register (struct regcache *regcache, int regno, char *buf)
 {
-  int size = register_size (regcache->tdesc, regno);
-
   memset (buf, 0, sizeof (long));
 
-  if (size < sizeof (long))
-    collect_register (regcache, regno, buf + sizeof (long) - size);
+  if (__BYTE_ORDER == __LITTLE_ENDIAN)
+    {
+      /* Little-endian values always sit at the left end of the buffer.  */
+      collect_register (regcache, regno, buf);
+    }
+  else if (__BYTE_ORDER == __BIG_ENDIAN)
+    {
+      /* Big-endian values sit at the right end of the buffer.  In case of
+         registers whose sizes are smaller than sizeof (long), we must use a
+         padding to access them correctly.  */
+      int size = register_size (regcache->tdesc, regno);
+
+      if (size < sizeof (long))
+	collect_register (regcache, regno, buf + sizeof (long) - size);
+      else
+	collect_register (regcache, regno, buf);
+    }
   else
-    collect_register (regcache, regno, buf);
+    perror_with_name ("Unexpected byte order");
 }
 
 static void
 ppc_supply_ptrace_register (struct regcache *regcache,
 			    int regno, const char *buf)
 {
-  int size = register_size (regcache->tdesc, regno);
-  if (size < sizeof (long))
-    supply_register (regcache, regno, buf + sizeof (long) - size);
+  if (__BYTE_ORDER == __LITTLE_ENDIAN)
+    {
+      /* Little-endian values always sit at the left end of the buffer.  */
+      supply_register (regcache, regno, buf);
+    }
+  else if (__BYTE_ORDER == __BIG_ENDIAN)
+    {
+      /* Big-endian values sit at the right end of the buffer.  In case of
+         registers whose sizes are smaller than sizeof (long), we must use a
+         padding to access them correctly.  */
+      int size = register_size (regcache->tdesc, regno);
+
+      if (size < sizeof (long))
+	supply_register (regcache, regno, buf + sizeof (long) - size);
+      else
+	supply_register (regcache, regno, buf);
+    }
   else
-    supply_register (regcache, regno, buf);
+    perror_with_name ("Unexpected byte order");
 }
 
 
-- 
1.7.9.5