perf probe: Add bitfield member support

Add bitfield member accessing support to probe arguments.

Suggested-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20110204125211.9507.60265.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
[ committer note: Fixed up '%lu' use for return of BYTES_TO_BITS ('%zd') ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 46addfb..fe461f6 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -33,6 +33,7 @@
 #include <ctype.h>
 #include <dwarf-regs.h>
 
+#include <linux/bitops.h>
 #include "event.h"
 #include "debug.h"
 #include "util.h"
@@ -333,13 +334,23 @@ static Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
        return vr_die;
 }
 
-static bool die_is_signed_type(Dwarf_Die *tp_die)
+static int die_get_attr_udata(Dwarf_Die *tp_die, unsigned int attr_name,
+                             Dwarf_Word *result)
 {
        Dwarf_Attribute attr;
+
+       if (dwarf_attr(tp_die, attr_name, &attr) == NULL ||
+           dwarf_formudata(&attr, result) != 0)
+               return -ENOENT;
+
+       return 0;
+}
+
+static bool die_is_signed_type(Dwarf_Die *tp_die)
+{
        Dwarf_Word ret;
 
-       if (dwarf_attr(tp_die, DW_AT_encoding, &attr) == NULL ||
-           dwarf_formudata(&attr, &ret) != 0)
+       if (die_get_attr_udata(tp_die, DW_AT_encoding, &ret))
                return false;
 
        return (ret == DW_ATE_signed_char || ret == DW_ATE_signed ||
@@ -348,11 +359,29 @@ static bool die_is_signed_type(Dwarf_Die *tp_die)
 
 static int die_get_byte_size(Dwarf_Die *tp_die)
 {
-       Dwarf_Attribute attr;
        Dwarf_Word ret;
 
-       if (dwarf_attr(tp_die, DW_AT_byte_size, &attr) == NULL ||
-           dwarf_formudata(&attr, &ret) != 0)
+       if (die_get_attr_udata(tp_die, DW_AT_byte_size, &ret))
+               return 0;
+
+       return (int)ret;
+}
+
+static int die_get_bit_size(Dwarf_Die *tp_die)
+{
+       Dwarf_Word ret;
+
+       if (die_get_attr_udata(tp_die, DW_AT_bit_size, &ret))
+               return 0;
+
+       return (int)ret;
+}
+
+static int die_get_bit_offset(Dwarf_Die *tp_die)
+{
+       Dwarf_Word ret;
+
+       if (die_get_attr_udata(tp_die, DW_AT_bit_offset, &ret))
                return 0;
 
        return (int)ret;
@@ -827,6 +856,8 @@ static_var:
        return 0;
 }
 
+#define BYTES_TO_BITS(nb)      ((nb) * BITS_PER_LONG / sizeof(long))
+
 static int convert_variable_type(Dwarf_Die *vr_die,
                                 struct probe_trace_arg *tvar,
                                 const char *cast)
@@ -843,6 +874,14 @@ static int convert_variable_type(Dwarf_Die *vr_die,
                return (tvar->type == NULL) ? -ENOMEM : 0;
        }
 
+       if (die_get_bit_size(vr_die) != 0) {
+               /* This is a bitfield */
+               ret = snprintf(buf, 16, "b%d@%d/%zd", die_get_bit_size(vr_die),
+                               die_get_bit_offset(vr_die),
+                               BYTES_TO_BITS(die_get_byte_size(vr_die)));
+               goto formatted;
+       }
+
        if (die_get_real_type(vr_die, &type) == NULL) {
                pr_warning("Failed to get a type information of %s.\n",
                           dwarf_diename(vr_die));
@@ -887,29 +926,31 @@ static int convert_variable_type(Dwarf_Die *vr_die,
                return (tvar->type == NULL) ? -ENOMEM : 0;
        }
 
-       ret = die_get_byte_size(&type) * 8;
-       if (ret) {
-               /* Check the bitwidth */
-               if (ret > MAX_BASIC_TYPE_BITS) {
-                       pr_info("%s exceeds max-bitwidth."
-                               " Cut down to %d bits.\n",
-                               dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
-                       ret = MAX_BASIC_TYPE_BITS;
-               }
+       ret = BYTES_TO_BITS(die_get_byte_size(&type));
+       if (!ret)
+               /* No size ... try to use default type */
+               return 0;
 
-               ret = snprintf(buf, 16, "%c%d",
-                              die_is_signed_type(&type) ? 's' : 'u', ret);
-               if (ret < 0 || ret >= 16) {
-                       if (ret >= 16)
-                               ret = -E2BIG;
-                       pr_warning("Failed to convert variable type: %s\n",
-                                  strerror(-ret));
-                       return ret;
-               }
-               tvar->type = strdup(buf);
-               if (tvar->type == NULL)
-                       return -ENOMEM;
+       /* Check the bitwidth */
+       if (ret > MAX_BASIC_TYPE_BITS) {
+               pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
+                       dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
+               ret = MAX_BASIC_TYPE_BITS;
+       }
+       ret = snprintf(buf, 16, "%c%d",
+                      die_is_signed_type(&type) ? 's' : 'u', ret);
+
+formatted:
+       if (ret < 0 || ret >= 16) {
+               if (ret >= 16)
+                       ret = -E2BIG;
+               pr_warning("Failed to convert variable type: %s\n",
+                          strerror(-ret));
+               return ret;
        }
+       tvar->type = strdup(buf);
+       if (tvar->type == NULL)
+               return -ENOMEM;
        return 0;
 }