perf probe: can't find unnamed union members

perf probe: can't find unnamed union members

[Arnaldo Carvalho de Melo]

Hi Masami,

[root@zoo ~]# perf probe -x ~/bin/perf -L lock__delete <lock__delete@/home/git/linux/tools/perf/util/annotate.c:0>
      0  static void lock__delete(struct ins_operands *ops)
      1  {
      2         struct ins *ins = ops->locked.ins;
         
      4         if (ins && ins->ops->free)
      5                 ins->ops->free(ops->locked.ops);
                else
      7                 ins__delete(ops->locked.ops);
         
      9         zfree(&ops->locked.ops);
     10         zfree(&ops->target.raw);
     11         zfree(&ops->target.name);
     12  }

And:

[root@zoo ~]# pahole ~/bin/perf -C ins_operands
struct ins_operands {
	char *                     raw;                  /*     0     8 */
	struct {
		char *             raw;                  /*     8     8 */
		char *             name;                 /*    16     8 */
		u64                addr;                 /*    24     8 */
		u64                offset;               /*    32     8 */
	} target;                                        /*     8    32 */
	union {
		struct {
			char *     raw;                  /*    40     8 */
			char *     name;                 /*    48     8 */
			u64        addr;                 /*    56     8 */
		} source;                                /*          24 */
		struct {
			struct ins * ins;                /*    40     8 */
			struct ins_operands * ops;       /*    48     8 */
		} locked;                                /*          16 */
	};                                               /*    40    24 */
	/* --- cacheline 1 boundary (64 bytes) --- */

	/* size: 64, cachelines: 1, members: 3 */
};
[root@zoo ~]#

But:

[root@zoo ~]# perf probe -x ~/bin/perf lock__delete ops 'locked_ops=ops->locked.ops'
ops(type:ins_operands) has no member locked.
  Error: Failed to add events.
[root@zoo ~]# 

Yes, it has :-)

- Arnaldo

Re: perf probe: can't find unnamed union members

[Masami Hiramatsu]

Hi,

(2015/03/06 0:32), Arnaldo Carvalho de Melo wrote:
> 
> Hi Masami,
> 
> [root@zoo ~]# perf probe -x ~/bin/perf -L lock__delete <lock__delete@/home/git/linux/tools/perf/util/annotate.c:0>
>       0  static void lock__delete(struct ins_operands *ops)
>       1  {
>       2         struct ins *ins = ops->locked.ins;
>          
>       4         if (ins && ins->ops->free)
>       5                 ins->ops->free(ops->locked.ops);
>                 else
>       7                 ins__delete(ops->locked.ops);
>          
>       9         zfree(&ops->locked.ops);
>      10         zfree(&ops->target.raw);
>      11         zfree(&ops->target.name);
>      12  }
> 
> And:
> 
> [root@zoo ~]# pahole ~/bin/perf -C ins_operands
> struct ins_operands {
> 	char *                     raw;                  /*     0     8 */
> 	struct {
> 		char *             raw;                  /*     8     8 */
> 		char *             name;                 /*    16     8 */
> 		u64                addr;                 /*    24     8 */
> 		u64                offset;               /*    32     8 */
> 	} target;                                        /*     8    32 */
> 	union {
> 		struct {
> 			char *     raw;                  /*    40     8 */
> 			char *     name;                 /*    48     8 */
> 			u64        addr;                 /*    56     8 */
> 		} source;                                /*          24 */
> 		struct {
> 			struct ins * ins;                /*    40     8 */
> 			struct ins_operands * ops;       /*    48     8 */
> 		} locked;                                /*          16 */
> 	};                                               /*    40    24 */
> 	/* --- cacheline 1 boundary (64 bytes) --- */
> 
> 	/* size: 64, cachelines: 1, members: 3 */
> };
> [root@zoo ~]#
> 
> But:
> 
> [root@zoo ~]# perf probe -x ~/bin/perf lock__delete ops 'locked_ops=ops->locked.ops'
> ops(type:ins_operands) has no member locked.
>   Error: Failed to add events.
> [root@zoo ~]# 
> 
> Yes, it has :-)

Oh, I see. That is not yet supported.
Here, I got the structure in debuginfo.

 [ fac4e]    structure_type
             name                 (strp) "ins_operands"
             byte_size            (data1) 64
             decl_file            (data1) 5
             decl_line            (data1) 16
             sibling              (ref4) [ fac79]
 [ fac5a]      member
               name                 (string) "raw"
               decl_file            (data1) 5
               decl_line            (data1) 17
               type                 (ref4) [ f8bdb]
               data_member_location (data1) 0
 [ fac66]      member
               name                 (strp) "target"
               decl_file            (data1) 5
               decl_line            (data1) 23
               type                 (ref4) [ fab9c]
               data_member_location (data1) 8
 [ fac72]      member					<= here is the unnamed one
               type                 (ref4) [ fac7f]
               data_member_location (data1) 28
 [ fac79]    pointer_type
             byte_size            (data1) 8
             type                 (ref4) [ fac4e]
 [ fac7f]    union_type
             byte_size            (data1) 24
             decl_file            (data1) 5
             decl_line            (data1) 24
             sibling              (ref4) [ fac9e]
 [ fac87]      member
               name                 (strp) "source"
               decl_file            (data1) 5
               decl_line            (data1) 29
               type                 (ref4) [ fabd5]
 [ fac92]      member					<= here is actual member
               name                 (strp) "locked"
               decl_file            (data1) 5
               decl_line            (data1) 33
               type                 (ref4) [ fac02]

Let me see how I can solve this...

Thank you for reporting!

> 
> - Arnaldo
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

[PATCH perf/core ] perf-probe: Fix to track down unnamed union/structure members

[Masami Hiramatsu]

Fix perf probe to track down unnamed union/structure members.
perf probe did not track down the tree of unnamed union/structure
members, since it just failed to find given "name" in a parent
structure/union. To solve this issue, I've introduced 2 changes.

- Fix die_find_member() to track down the type-DIE if it is
  unnamed, and if it contains the specified member, returns the
  unnamed member.
  (note that we don't return found member, since unnamed member
   has the offset in the parent structure)
- Fix convert_variable_fields() to track down the unnamed union/
  structure (one-by-one).

With this patch, perf probe can access unnamed fields.
  -----
  #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
  Added new event:
    probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)

  You can now use it in all perf tools, such as:

          perf record -e probe_perf:lock__delete -aR sleep 1
  -----

The original report of this issue is: https://lkml.org/lkml/2015/3/5/431

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
---
 tools/perf/util/dwarf-aux.c    |   14 ++++++++++----
 tools/perf/util/probe-finder.c |    8 +++++++-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 780b2bc..c34e024 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -801,10 +801,16 @@ static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
 {
 	const char *name = data;
 
-	if ((dwarf_tag(die_mem) == DW_TAG_member) &&
-	    die_compare_name(die_mem, name))
-		return DIE_FIND_CB_END;
-
+	if (dwarf_tag(die_mem) == DW_TAG_member) {
+		if (die_compare_name(die_mem, name))
+			return DIE_FIND_CB_END;
+		else if (!dwarf_diename(die_mem)) {	/* Unnamed structure */
+			Dwarf_Die type_die, tmp_die;
+			if (die_get_type(die_mem, &type_die) &&
+			    die_find_member(&type_die, name, &tmp_die))
+				return DIE_FIND_CB_END;
+		}
+	}
 	return DIE_FIND_CB_SIBLING;
 }
 
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 46f009a..3898eba 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -460,7 +460,8 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 			       " nor array.\n", varname);
 			return -EINVAL;
 		}
-		if (field->ref) {
+		/* While prcessing unnamed field, we don't care about this */
+		if (field->ref && !dwarf_diename(vr_die)) {
 			pr_err("Semantic error: %s must be referred by '.'\n",
 			       field->name);
 			return -EINVAL;
@@ -491,6 +492,11 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 	}
 	ref->offset += (long)offs;
 
+	/* If this member is unnamed, we need to reuse this field */
+	if (!dwarf_diename(die_mem))
+		return convert_variable_fields(die_mem, varname, field,
+						&ref, die_mem);
+
 next:
 	/* Converting next field */
 	if (field->next)

Re: [PATCH perf/core ] perf-probe: Fix to track down unnamed union/structure members

[Masami Hiramatsu]

Ping?

(2015/03/09 11:15), Masami Hiramatsu wrote:
> Fix perf probe to track down unnamed union/structure members.
> perf probe did not track down the tree of unnamed union/structure
> members, since it just failed to find given "name" in a parent
> structure/union. To solve this issue, I've introduced 2 changes.
> 
> - Fix die_find_member() to track down the type-DIE if it is
>   unnamed, and if it contains the specified member, returns the
>   unnamed member.
>   (note that we don't return found member, since unnamed member
>    has the offset in the parent structure)
> - Fix convert_variable_fields() to track down the unnamed union/
>   structure (one-by-one).
> 
> With this patch, perf probe can access unnamed fields.
>   -----
>   #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
>   Added new event:
>     probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)
> 
>   You can now use it in all perf tools, such as:
> 
>           perf record -e probe_perf:lock__delete -aR sleep 1
>   -----
> 
> The original report of this issue is: https://lkml.org/lkml/2015/3/5/431
> 
> Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> ---
>  tools/perf/util/dwarf-aux.c    |   14 ++++++++++----
>  tools/perf/util/probe-finder.c |    8 +++++++-
>  2 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 780b2bc..c34e024 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -801,10 +801,16 @@ static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
>  {
>  	const char *name = data;
>  
> -	if ((dwarf_tag(die_mem) == DW_TAG_member) &&
> -	    die_compare_name(die_mem, name))
> -		return DIE_FIND_CB_END;
> -
> +	if (dwarf_tag(die_mem) == DW_TAG_member) {
> +		if (die_compare_name(die_mem, name))
> +			return DIE_FIND_CB_END;
> +		else if (!dwarf_diename(die_mem)) {	/* Unnamed structure */
> +			Dwarf_Die type_die, tmp_die;
> +			if (die_get_type(die_mem, &type_die) &&
> +			    die_find_member(&type_die, name, &tmp_die))
> +				return DIE_FIND_CB_END;
> +		}
> +	}
>  	return DIE_FIND_CB_SIBLING;
>  }
>  
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 46f009a..3898eba 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -460,7 +460,8 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
>  			       " nor array.\n", varname);
>  			return -EINVAL;
>  		}
> -		if (field->ref) {
> +		/* While prcessing unnamed field, we don't care about this */
> +		if (field->ref && !dwarf_diename(vr_die)) {
>  			pr_err("Semantic error: %s must be referred by '.'\n",
>  			       field->name);
>  			return -EINVAL;
> @@ -491,6 +492,11 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
>  	}
>  	ref->offset += (long)offs;
>  
> +	/* If this member is unnamed, we need to reuse this field */
> +	if (!dwarf_diename(die_mem))
> +		return convert_variable_fields(die_mem, varname, field,
> +						&ref, die_mem);
> +
>  next:
>  	/* Converting next field */
>  	if (field->next)
> 
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

Re: [PATCH perf/core ] perf-probe: Fix to track down unnamed union/structure members

[Arnaldo Carvalho de Melo]

Em Wed, Apr 01, 2015 at 06:08:17PM +0900, Masami Hiramatsu escreveu:
> Ping?

<SNIP>

> > With this patch, perf probe can access unnamed fields.
> >   -----
> >   #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
> >   Added new event:
> >     probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)

> >   You can now use it in all perf tools, such as:

> >           perf record -e probe_perf:lock__delete -aR sleep 1
> >   -----

> > The original report of this issue is: https://lkml.org/lkml/2015/3/5/431

what am I doing wrong?

[root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops'
Added new event:
  probe_perf:lock__delete (on lock__delete in /home/acme/bin/perf with locked_ops=ops)

You can now use it in all perf tools, such as:

	perf record -e probe_perf:lock__delete -aR sleep 1

[root@ssdandy ~]# perf probe -d probe_perf:*
Removed event: probe_perf:lock__delete
[root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops->locked'
Semantic error: locked must be referred by '.'
  Error: Failed to add events.
[root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops.locked'
Semantic error: locked must be referred by '->'
  Error: Failed to add events.
[root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops->locked'
Semantic error: locked must be referred by '.'
  Error: Failed to add events.
[root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops->locked.ops'
Semantic error: locked must be referred by '.'
  Error: Failed to add events.
[root@ssdandy ~]#

Re: Re: [PATCH perf/core ] perf-probe: Fix to track down unnamed union/structure members

[Masami Hiramatsu]

(2015/04/01 23:41), Arnaldo Carvalho de Melo wrote:
> Em Wed, Apr 01, 2015 at 06:08:17PM +0900, Masami Hiramatsu escreveu:
>> Ping?
> 
> <SNIP>
> 
>>> With this patch, perf probe can access unnamed fields.
>>>   -----
>>>   #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
>>>   Added new event:
>>>     probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)
> 
>>>   You can now use it in all perf tools, such as:
> 
>>>           perf record -e probe_perf:lock__delete -aR sleep 1
>>>   -----
> 
>>> The original report of this issue is: https://lkml.org/lkml/2015/3/5/431
> 
> what am I doing wrong?
> 
> [root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops'
> Added new event:
>   probe_perf:lock__delete (on lock__delete in /home/acme/bin/perf with locked_ops=ops)
> 
> You can now use it in all perf tools, such as:
> 
> 	perf record -e probe_perf:lock__delete -aR sleep 1
> 
> [root@ssdandy ~]# perf probe -d probe_perf:*
> Removed event: probe_perf:lock__delete
> [root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops->locked'
> Semantic error: locked must be referred by '.'
>   Error: Failed to add events.
> [root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops.locked'
> Semantic error: locked must be referred by '->'
>   Error: Failed to add events.
> [root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops->locked'
> Semantic error: locked must be referred by '.'
>   Error: Failed to add events.
> [root@ssdandy ~]# perf probe ~acme/bin/perf lock__delete 'locked_ops=ops->locked.ops'
> Semantic error: locked must be referred by '.'
>   Error: Failed to add events.
> [root@ssdandy ~]#

Oops, thank you for reporting!
I must miss something...

Thank you,

> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 


-- 
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@hitachi.com

Re: [PATCH perf/core ] perf-probe: Fix to track down unnamed union/structure members

[Masami Hiramatsu]

(2015/03/09 11:15), Masami Hiramatsu wrote:
> Fix perf probe to track down unnamed union/structure members.
> perf probe did not track down the tree of unnamed union/structure
> members, since it just failed to find given "name" in a parent
> structure/union. To solve this issue, I've introduced 2 changes.
> 
> - Fix die_find_member() to track down the type-DIE if it is
>   unnamed, and if it contains the specified member, returns the
>   unnamed member.
>   (note that we don't return found member, since unnamed member
>    has the offset in the parent structure)
> - Fix convert_variable_fields() to track down the unnamed union/
>   structure (one-by-one).
> 
> With this patch, perf probe can access unnamed fields.
>   -----
>   #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
>   Added new event:
>     probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)
> 
>   You can now use it in all perf tools, such as:
> 
>           perf record -e probe_perf:lock__delete -aR sleep 1
>   -----
> 
> The original report of this issue is: https://lkml.org/lkml/2015/3/5/431
> 
> Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> ---
>  tools/perf/util/dwarf-aux.c    |   14 ++++++++++----
>  tools/perf/util/probe-finder.c |    8 +++++++-
>  2 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 780b2bc..c34e024 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -801,10 +801,16 @@ static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
>  {
>  	const char *name = data;
>  
> -	if ((dwarf_tag(die_mem) == DW_TAG_member) &&
> -	    die_compare_name(die_mem, name))
> -		return DIE_FIND_CB_END;
> -
> +	if (dwarf_tag(die_mem) == DW_TAG_member) {
> +		if (die_compare_name(die_mem, name))
> +			return DIE_FIND_CB_END;
> +		else if (!dwarf_diename(die_mem)) {	/* Unnamed structure */
> +			Dwarf_Die type_die, tmp_die;
> +			if (die_get_type(die_mem, &type_die) &&
> +			    die_find_member(&type_die, name, &tmp_die))
> +				return DIE_FIND_CB_END;
> +		}
> +	}
>  	return DIE_FIND_CB_SIBLING;
>  }
>  
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 46f009a..3898eba 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -460,7 +460,8 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
>  			       " nor array.\n", varname);
>  			return -EINVAL;
>  		}
> -		if (field->ref) {
> +		/* While prcessing unnamed field, we don't care about this */
> +		if (field->ref && !dwarf_diename(vr_die)) {
                                  ^^ Oops! this should be inverted!
I've missed to include a local fix to this patch...

Thank you,

>  			pr_err("Semantic error: %s must be referred by '.'\n",
>  			       field->name);
>  			return -EINVAL;
> @@ -491,6 +492,11 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
>  	}
>  	ref->offset += (long)offs;
>  
> +	/* If this member is unnamed, we need to reuse this field */
> +	if (!dwarf_diename(die_mem))
> +		return convert_variable_fields(die_mem, varname, field,
> +						&ref, die_mem);
> +
>  next:
>  	/* Converting next field */
>  	if (field->next)
> 
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

[PATCH perf/core v2] perf-probe: Fix to track down unnamed union/structure members

[Masami Hiramatsu]

Fix perf probe to track down unnamed union/structure members.
perf probe did not track down the tree of unnamed union/structure
members, since it just failed to find given "name" in a parent
structure/union. To solve this issue, I've introduced 2 changes.

- Fix die_find_member() to track down the type-DIE if it is
  unnamed, and if it contains the specified member, returns the
  unnamed member.
  (note that we don't return found member, since unnamed member
   has the offset in the parent structure)
- Fix convert_variable_fields() to track down the unnamed union/
  structure (one-by-one).

With this patch, perf probe can access unnamed fields.
  -----
  #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
  Added new event:
    probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)

  You can now use it in all perf tools, such as:

          perf record -e probe_perf:lock__delete -aR sleep 1
  -----

The original report of this issue is: https://lkml.org/lkml/2015/3/5/431

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
---
 tools/perf/util/dwarf-aux.c    |   14 ++++++++++----
 tools/perf/util/probe-finder.c |    8 +++++++-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 780b2bc..c34e024 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -801,10 +801,16 @@ static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
 {
 	const char *name = data;
 
-	if ((dwarf_tag(die_mem) == DW_TAG_member) &&
-	    die_compare_name(die_mem, name))
-		return DIE_FIND_CB_END;
-
+	if (dwarf_tag(die_mem) == DW_TAG_member) {
+		if (die_compare_name(die_mem, name))
+			return DIE_FIND_CB_END;
+		else if (!dwarf_diename(die_mem)) {	/* Unnamed structure */
+			Dwarf_Die type_die, tmp_die;
+			if (die_get_type(die_mem, &type_die) &&
+			    die_find_member(&type_die, name, &tmp_die))
+				return DIE_FIND_CB_END;
+		}
+	}
 	return DIE_FIND_CB_SIBLING;
 }
 
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 46f009a..7831e2d 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -460,7 +460,8 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 			       " nor array.\n", varname);
 			return -EINVAL;
 		}
-		if (field->ref) {
+		/* While prcessing unnamed field, we don't care about this */
+		if (field->ref && dwarf_diename(vr_die)) {
 			pr_err("Semantic error: %s must be referred by '.'\n",
 			       field->name);
 			return -EINVAL;
@@ -491,6 +492,11 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 	}
 	ref->offset += (long)offs;
 
+	/* If this member is unnamed, we need to reuse this field */
+	if (!dwarf_diename(die_mem))
+		return convert_variable_fields(die_mem, varname, field,
+						&ref, die_mem);
+
 next:
 	/* Converting next field */
 	if (field->next)

Re: [PATCH perf/core v2] perf-probe: Fix to track down unnamed union/structure members

[Arnaldo Carvalho de Melo]

Em Thu, Apr 02, 2015 at 04:33:12PM +0900, Masami Hiramatsu escreveu:
> Fix perf probe to track down unnamed union/structure members.
> perf probe did not track down the tree of unnamed union/structure
> members, since it just failed to find given "name" in a parent
> structure/union. To solve this issue, I've introduced 2 changes.
> 
> - Fix die_find_member() to track down the type-DIE if it is
>   unnamed, and if it contains the specified member, returns the
>   unnamed member.
>   (note that we don't return found member, since unnamed member
>    has the offset in the parent structure)
> - Fix convert_variable_fields() to track down the unnamed union/
>   structure (one-by-one).
> 
> With this patch, perf probe can access unnamed fields.
>   -----
>   #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
>   Added new event:
>     probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)
> 
>   You can now use it in all perf tools, such as:
> 
>           perf record -e probe_perf:lock__delete -aR sleep 1
>   -----
> 
> The original report of this issue is: https://lkml.org/lkml/2015/3/5/431

Thanks a lot! Applied, built and tested, all works as expected,

Merged,

- Arnaldo

[tip:perf/core] perf probe: Fix to track down unnamed union/ structure members

[tip-bot for Masami Hiramatsu]

Commit-ID:  c72738355b2ac79506fbfa10ffee8fe3a27e69da
Gitweb:     http://git.kernel.org/tip/c72738355b2ac79506fbfa10ffee8fe3a27e69da
Author:     Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
AuthorDate: Thu, 2 Apr 2015 16:33:12 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 2 Apr 2015 13:18:44 -0300

perf probe: Fix to track down unnamed union/structure members

Fix 'perf probe' to track down unnamed union/structure members.

perf probe did not track down the tree of unnamed union/structure
members, since it just failed to find given "name" in a parent
structure/union.  To solve this issue, I've introduced 2 changes.

- Fix die_find_member() to track down the type-DIE if it is
  unnamed, and if it contains the specified member, returns the
  unnamed member.
  (note that we don't return found member, since unnamed member
   has the offset in the parent structure)
- Fix convert_variable_fields() to track down the unnamed union/
  structure (one-by-one).

With this patch, perf probe can access unnamed fields:
  -----
  #./perf probe -nfx ./perf lock__delete ops 'locked_ops=ops->locked.ops'
  Added new event:
    probe_perf:lock__delete (on lock__delete in /home/mhiramat/ksrc/linux-3/tools/perf/perf with ops locked_ops=ops->locked.ops)

  You can now use it in all perf tools, such as:

          perf record -e probe_perf:lock__delete -aR sleep 1
  -----

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Report-Link: https://lkml.org/lkml/2015/3/5/431
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150402073312.14482.37942.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/dwarf-aux.c    | 14 ++++++++++----
 tools/perf/util/probe-finder.c |  8 +++++++-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 780b2bc..c34e024 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -801,10 +801,16 @@ static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
 {
 	const char *name = data;
 
-	if ((dwarf_tag(die_mem) == DW_TAG_member) &&
-	    die_compare_name(die_mem, name))
-		return DIE_FIND_CB_END;
-
+	if (dwarf_tag(die_mem) == DW_TAG_member) {
+		if (die_compare_name(die_mem, name))
+			return DIE_FIND_CB_END;
+		else if (!dwarf_diename(die_mem)) {	/* Unnamed structure */
+			Dwarf_Die type_die, tmp_die;
+			if (die_get_type(die_mem, &type_die) &&
+			    die_find_member(&type_die, name, &tmp_die))
+				return DIE_FIND_CB_END;
+		}
+	}
 	return DIE_FIND_CB_SIBLING;
 }
 
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 46f009a..7831e2d 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -460,7 +460,8 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 			       " nor array.\n", varname);
 			return -EINVAL;
 		}
-		if (field->ref) {
+		/* While prcessing unnamed field, we don't care about this */
+		if (field->ref && dwarf_diename(vr_die)) {
 			pr_err("Semantic error: %s must be referred by '.'\n",
 			       field->name);
 			return -EINVAL;
@@ -491,6 +492,11 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 	}
 	ref->offset += (long)offs;
 
+	/* If this member is unnamed, we need to reuse this field */
+	if (!dwarf_diename(die_mem))
+		return convert_variable_fields(die_mem, varname, field,
+						&ref, die_mem);
+
 next:
 	/* Converting next field */
 	if (field->next)