LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Masami Hiramatsu <mhiramat@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [BUGFIX PATCH 1/4] perf probe: Skip end-of-sequence and non statement lines
Date: Wed, 30 Oct 2019 16:09:21 +0900
Message-ID: <157241936090.32002.12156347518596111660.stgit@devnote2> (raw)
In-Reply-To: <157241935028.32002.10228194508152968737.stgit@devnote2>

Skip end-of-sequence and non-statement lines while walking
through lines list.

The "end-of-sequence" line information means
 "the current address is that of the first byte after the
  end of a sequence of target machine instructions."
 (DWARF version 4 spec 6.2.2)
This actually means out of scope and we can not probe on it.

On the other hand, the statement lines (is_stmt) means
 "the current instruction is a recommended breakpoint location.
  A recommended breakpoint location is intended to “represent”
  a line, a statement and/or a semantically distinct subpart
  of a statement."
 (DWARF version 4 spec 6.2.2)
So, non-statement line info also should be skipped.

These can reduce unneeded probe points and also avoid an error.

E.g. without this patch,
  # perf probe -a "clear_tasks_mm_cpumask:1"
  Added new events:
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:1)
    probe:clear_tasks_mm_cpumask_2 (on clear_tasks_mm_cpumask:1)
    probe:clear_tasks_mm_cpumask_3 (on clear_tasks_mm_cpumask:1)
    probe:clear_tasks_mm_cpumask_4 (on clear_tasks_mm_cpumask:1)

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

  	perf record -e probe:clear_tasks_mm_cpumask_4 -aR sleep 1

  #

This puts 5 probes on one line, but acutally it's not inlined
function. This is because there are many non statement instructions
at the function prologue.

With this patch,
  # perf probe -a "clear_tasks_mm_cpumask:1"
  Added new event:
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)

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

  	perf record -e probe:clear_tasks_mm_cpumask -aR sleep 1

  #

Now perf-probe skips unneeded addresses.

Fixes: 4cc9cec636e7 ("perf probe: Introduce lines walker interface")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/dwarf-aux.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index ac82fd937e4b..f31001d13bfb 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -782,6 +782,7 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 	int decl = 0, inl;
 	Dwarf_Die die_mem, *cu_die;
 	size_t nlines, i;
+	bool flag;
 
 	/* Get the CU die */
 	if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
@@ -812,6 +813,12 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 				  "Possible error in debuginfo.\n");
 			continue;
 		}
+		/* Skip end-of-sequence */
+		if (dwarf_lineendsequence(line, &flag) != 0 || flag)
+			continue;
+		/* Skip Non statement line-info */
+		if (dwarf_linebeginstatement(line, &flag) != 0 || !flag)
+			continue;
 		/* Filter lines based on address */
 		if (rt_die != cu_die) {
 			/*


  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30  7:09 [BUGFIX PATCH 0/4] perf probe: Fixes bugs in show-lines and show vars etc Masami Hiramatsu
2019-10-30  7:09 ` Masami Hiramatsu [this message]
2019-11-06 20:04   ` [BUGFIX PATCH 1/4] perf probe: Skip end-of-sequence and non statement lines Arnaldo Carvalho de Melo
2020-01-10  9:29     ` Rantala, Tommi T. (Nokia - FI/Espoo)
2020-01-10 15:43       ` Masami Hiramatsu
2019-11-12 11:17   ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2019-10-30  7:09 ` [BUGFIX PATCH 2/4] perf probe: Filter out instances except for inlined subroutine and subprogram Masami Hiramatsu
2019-11-06 20:06   ` Arnaldo Carvalho de Melo
2019-11-12 11:17   ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2019-10-30  7:09 ` [BUGFIX PATCH 3/4] perf probe: Fix to show calling lines of inlined functions Masami Hiramatsu
2019-11-06 20:08   ` Arnaldo Carvalho de Melo
2019-11-12 11:17   ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2019-10-30  7:09 ` [BUGFIX PATCH 4/4] perf probe: Skip overlapped location on searching variables Masami Hiramatsu
2019-11-06 20:09   ` Arnaldo Carvalho de Melo
2019-11-12 11:17   ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=157241936090.32002.12156347518596111660.stgit@devnote2 \
    --to=mhiramat@kernel.org \
    --cc=acme@kernel.org \
    --cc=jolsa@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=namhyung@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git