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Subject[PATCH -perf/perf/core 4/4] perf/probe: Add bitfield member support
Date
Add bitfield member accessing support to probe arguments.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Suggested-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org
---
tools/perf/util/probe-finder.c | 95 +++++++++++++++++++++++++++++-----------
1 files changed, 68 insertions(+), 27 deletions(-)
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 69215bf..613e5fb 100644
--- 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/%lu", 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;
}



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