[PATCH 2/2] H8/300: Fix pseudo registers reads/writes.

[Pedro Alves <palves@redhat.com>]

'info registers ccr' corrupts memory.

Debugging gdb under Valgrind, we see:

 (gdb) info registers ccr
 ==23225== Invalid write of size 1
 ==23225==    at 0x4A0A308: memcpy@@GLIBC_2.14 (mc_replace_strmem.c:881)
 ==23225==    by 0x52D334: regcache_raw_read (regcache.c:625)
 ==23225==    by 0x45E4D8: h8300_pseudo_register_read (h8300-tdep.c:1171)
 ==23225==    by 0x5B694B: gdbarch_pseudo_register_read (gdbarch.c:1926)
 ==23225==    by 0x52DADB: regcache_cooked_read (regcache.c:740)
 ==23225==    by 0x52DC10: regcache_cooked_read_value (regcache.c:765)
 ==23225==    by 0x68CA41: sentinel_frame_prev_register (sentinel-frame.c:52)
 ==23225==    by 0x6B80CB: frame_unwind_register_value (frame.c:1105)
 ==23225==    by 0x6B7C97: frame_register_unwind (frame.c:1010)
 ==23225==    by 0x6B7F73: frame_unwind_register (frame.c:1064)
 ==23225==    by 0x6B8359: frame_unwind_register_signed (frame.c:1162)
 ==23225==    by 0x6B8396: get_frame_register_signed (frame.c:1169)
 ==23225==  Address 0x4f7b031 is 0 bytes after a block of size 1 alloc'd
 ==23225==    at 0x4A06B0F: calloc (vg_replace_malloc.c:593)
 ==23225==    by 0x6EB754: xcalloc (common-utils.c:91)
 ==23225==    by 0x6EB793: xzalloc (common-utils.c:101)
 ==23225==    by 0x53A782: allocate_value_contents (value.c:854)
 ==23225==    by 0x53A7B4: allocate_value (value.c:864)
 ==23225==    by 0x52DBC8: regcache_cooked_read_value (regcache.c:757)
 ==23225==    by 0x68CA41: sentinel_frame_prev_register (sentinel-frame.c:52)
 ==23225==    by 0x6B80CB: frame_unwind_register_value (frame.c:1105)
 ==23225==    by 0x6B7C97: frame_register_unwind (frame.c:1010)
 ==23225==    by 0x6B7F73: frame_unwind_register (frame.c:1064)
 ==23225==    by 0x6B8359: frame_unwind_register_signed (frame.c:1162)
 ==23225==    by 0x6B8396: get_frame_register_signed (frame.c:1169)
 ==23225==
 ccr            0x00        0    I-0 UI-0 H-0 U-0 N-0 Z-0 V-0 C-0 u> u>= != >= >
 (gdb)

This bit:

 ==23225== Invalid write of size 1
 ==23225==    at 0x4A0A308: memcpy@@GLIBC_2.14 (mc_replace_strmem.c:881)
 ==23225==    by 0x52D334: regcache_raw_read (regcache.c:625)
 ==23225==    by 0x45E4D8: h8300_pseudo_register_read (h8300-tdep.c:1171)

shows the problem.  The CCR pseudo register has type length of 1,
while the corresponding CCR raw register has a length of 2 or 4
(depending on mode).  In
sim/h8300/compile.c:sim_{fetch|store}_register we see that the sim
also treats those raw registers (CCR/EXR) as 2 or 4 bytes length.

gdb/
2014-02-12  Pedro Alves  <palves@redhat.com>

	* h8300-tdep.c (pseudo_from_raw_register)
	(raw_from_pseudo_register): New functions.
	(h8300_pseudo_register_read, h8300_pseudo_register_write): Use
	them.
---
 gdb/ChangeLog    |  7 +++++++
 gdb/h8300-tdep.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6f0f903..5e9e9b8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2014-02-12  Pedro Alves  <palves@redhat.com>
 
+	* h8300-tdep.c (pseudo_from_raw_register)
+	(raw_from_pseudo_register): New functions.
+	(h8300_pseudo_register_read, h8300_pseudo_register_write): Use
+	them.
+
+2014-02-12  Pedro Alves  <palves@redhat.com>
+
 	* h8300-tdep.c (h8300_register_sim_regno): New function.
 	(h8300_gdbarch_init): Install h8300_register_sim_regno as
 	gdbarch_register_sim_regno hook.
diff --git a/gdb/h8300-tdep.c b/gdb/h8300-tdep.c
index 4193287..98343e0 100644
--- a/gdb/h8300-tdep.c
+++ b/gdb/h8300-tdep.c
@@ -1164,15 +1164,55 @@ h8300_register_type (struct gdbarch *gdbarch, int regno)
     }
 }
 
+/* Helpers for h8300_pseudo_register_read.  We expose ccr/exr as
+   pseudo-registers to users with smaller sizes than the corresponding
+   raw registers.  These helpers extend/narrow the values.  */
+
+static enum register_status
+pseudo_from_raw_register (struct gdbarch *gdbarch, struct regcache *regcache,
+			  gdb_byte *buf, int pseudo_regno, int raw_regno)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  enum register_status status;
+  ULONGEST val;
+
+  status = regcache_raw_read_unsigned (regcache, raw_regno, &val);
+  if (status == REG_VALID)
+    store_unsigned_integer (buf,
+			    register_size (gdbarch, pseudo_regno),
+			    byte_order, val);
+  return status;
+}
+
+/* See pseudo_from_raw_register.  */
+
+static void
+raw_from_pseudo_register (struct gdbarch *gdbarch, struct regcache *regcache,
+			  const gdb_byte *buf, int raw_regno, int pseudo_regno)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  ULONGEST val;
+
+  val = extract_unsigned_integer (buf, register_size (gdbarch, pseudo_regno),
+				  byte_order);
+  regcache_raw_write_unsigned (regcache, raw_regno, val);
+}
+
 static enum register_status
 h8300_pseudo_register_read (struct gdbarch *gdbarch,
 			    struct regcache *regcache, int regno,
 			    gdb_byte *buf)
 {
   if (regno == E_PSEUDO_CCR_REGNUM (gdbarch))
-    return regcache_raw_read (regcache, E_CCR_REGNUM, buf);
+    {
+      return pseudo_from_raw_register (gdbarch, regcache, buf,
+				       regno, E_CCR_REGNUM);
+    }
   else if (regno == E_PSEUDO_EXR_REGNUM (gdbarch))
-    return regcache_raw_read (regcache, E_EXR_REGNUM, buf);
+    {
+      return pseudo_from_raw_register (gdbarch, regcache, buf,
+				       regno, E_EXR_REGNUM);
+    }
   else
     return regcache_raw_read (regcache, regno, buf);
 }
@@ -1183,9 +1223,9 @@ h8300_pseudo_register_write (struct gdbarch *gdbarch,
 			     const gdb_byte *buf)
 {
   if (regno == E_PSEUDO_CCR_REGNUM (gdbarch))
-    regcache_raw_write (regcache, E_CCR_REGNUM, buf);
+    raw_from_pseudo_register (gdbarch, regcache, buf, E_CCR_REGNUM, regno);
   else if (regno == E_PSEUDO_EXR_REGNUM (gdbarch))
-    regcache_raw_write (regcache, E_EXR_REGNUM, buf);
+    raw_from_pseudo_register (gdbarch, regcache, buf, E_EXR_REGNUM, regno);
   else
     regcache_raw_write (regcache, regno, buf);
 }
-- 
1.7.11.7