LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Jaewon Kim <jaewon31.kim@samsung.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Kees Cook <keescook@chromium.org>
Subject: [PATCH 3/3] tools lib traceevent: Add handler for __builtin_expect()
Date: Tue, 24 Mar 2020 16:08:48 -0400
Message-ID: <20200324200956.821799393@goodmis.org> (raw)
In-Reply-To: <20200324200845.763565368@goodmis.org>

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

In order to move pointer checks like IS_ERR_VALUE() out of the hotpath and
into the reader path of a trace event, user space tools need to be able to
parse that. IS_ERR_VALUE() is defined as:

 #define IS_ERR_VALUE() unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)

Which eventually turns into:

  __builtin_expect(!!((unsigned long)(void *)(x) >= (unsigned long)-4095), 0)

Now the traceevent parser can handle most of that except for the
__builtin_expect(), which needs to be added.

Link: https://lore.kernel.org/linux-mm/20200320055823.27089-3-jaewon31.kim@samsung.com/

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 tools/lib/traceevent/event-parse.c | 35 ++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 010e60d5a081..5b36c589a029 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -3084,6 +3084,37 @@ process_func_handler(struct tep_event *event, struct tep_function_handler *func,
 	return TEP_EVENT_ERROR;
 }
 
+static enum tep_event_type
+process_builtin_expect(struct tep_event *event, struct tep_print_arg *arg, char **tok)
+{
+	enum tep_event_type type;
+	char *token = NULL;
+
+	/* Handle __builtin_expect( cond, #) */
+	type = process_arg(event, arg, &token);
+
+	if (type != TEP_EVENT_DELIM || token[0] != ',')
+		goto out_free;
+
+	free_token(token);
+
+	/* We don't care what the second parameter is of the __builtin_expect() */
+	if (read_expect_type(TEP_EVENT_ITEM, &token) < 0)
+		goto out_free;
+
+	if (read_expected(TEP_EVENT_DELIM, ")") < 0)
+		goto out_free;
+
+	free_token(token);
+	type = read_token_item(tok);
+	return type;
+
+out_free:
+	free_token(token);
+	*tok = NULL;
+	return TEP_EVENT_ERROR;
+}
+
 static enum tep_event_type
 process_function(struct tep_event *event, struct tep_print_arg *arg,
 		 char *token, char **tok)
@@ -3128,6 +3159,10 @@ process_function(struct tep_event *event, struct tep_print_arg *arg,
 		free_token(token);
 		return process_dynamic_array_len(event, arg, tok);
 	}
+	if (strcmp(token, "__builtin_expect") == 0) {
+		free_token(token);
+		return process_builtin_expect(event, arg, tok);
+	}
 
 	func = find_func_handler(event->tep, token);
 	if (func) {
-- 
2.25.1



  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 20:08 [PATCH 0/3] tool lib traceevent: Fix some parsing errors Steven Rostedt
2020-03-24 20:08 ` [PATCH 1/3] tools lib traceevent: Add append() function helper for appending strings Steven Rostedt
2020-03-24 20:08 ` [PATCH 2/3] tools lib traceevent: Handle __attribute__((user)) in field names Steven Rostedt
2020-03-24 20:08 ` Steven Rostedt [this message]
2020-06-17 21:28 ` [PATCH 0/3] tool lib traceevent: Fix some parsing errors Steven Rostedt
2020-06-17 22:55   ` Arnaldo Carvalho de Melo
2020-06-18 13:24     ` Arnaldo Carvalho de Melo

Reply instructions:

You may reply publicly 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=20200324200956.821799393@goodmis.org \
    --to=rostedt@goodmis.org \
    --cc=acme@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=jaewon31.kim@samsung.com \
    --cc=jolsa@redhat.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-trace-devel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=namhyung@kernel.org \
    --cc=vbabka@suse.cz \
    /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