LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Namhyung Kim <namhyung@kernel.org>
Subject: [PATCH 05/10] lib traceevent: Handle new pointer processing of bprint strings
Date: Thu, 11 Jan 2018 19:47:46 -0500
Message-ID: <20180112004822.403349289@goodmis.org> (raw)
In-Reply-To: <20180112004741.378806573@goodmis.org>

[-- Attachment #0: 0005-lib-traceevent-Handle-new-pointer-processing-of-bpri.patch --]
[-- Type: text/plain, Size: 2323 bytes --]

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

The Linux kernel printf() has some extended use cases that dereference the
pointer. This is dangerouse for tracing because the pointer that is
dereferenced can change or even be unmapped. It also causes issues when the
trace data is extracted, because user space does not have access to the
contents of the pointer even if it still exists.

To handle this, the kernel was updated to process these dereferenced
pointers at the time they are recorded, and not post processed. Now they
exist in the tracing buffer, and no dereference is needed at the time of
reading the trace.

The event parsing library needs to handle this new case.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 tools/lib/traceevent/event-parse.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 8757dd64e42c..344a034a8fbc 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -4300,6 +4300,26 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
 				goto process_again;
 			case 'p':
 				ls = 1;
+				if (isalnum(ptr[1])) {
+					ptr++;
+					/* Check for special pointers */
+					switch (*ptr) {
+					case 's':
+					case 'S':
+					case 'f':
+					case 'F':
+						break;
+					default:
+						/*
+						 * Older kernels do not process
+						 * dereferenced pointers.
+						 * Only process if the pointer
+						 * value is a printable.
+						 */
+						if (isprint(*(char *)bptr))
+							goto process_string;
+					}
+				}
 				/* fall through */
 			case 'd':
 			case 'u':
@@ -4352,6 +4372,7 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
 
 				break;
 			case 's':
+ process_string:
 				arg = alloc_arg();
 				if (!arg) {
 					do_warning_event(event, "%s(%d): not enough memory!",
@@ -4959,6 +4980,11 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
 				if (isalnum(ptr[1]))
 					ptr++;
 
+				if (arg->type == PRINT_BSTRING) {
+					trace_seq_puts(s, arg->string.string);
+					break;
+				}
+
 				if (*ptr == 'F' || *ptr == 'f' ||
 				    *ptr == 'S' || *ptr == 's') {
 					show_func = *ptr;
-- 
2.13.2

  parent reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-12  0:47 [PATCH 00/10] tools lib traceveent: Pull updates from trace-cmd library Steven Rostedt
2018-01-12  0:47 ` [PATCH 01/10] lib, traceevent: Fix bad force_token escape sequence Steven Rostedt
2018-01-12  0:47 ` [PATCH 02/10] lib traceevent: Show value of flags that have not been parsed Steven Rostedt
2018-01-17 16:28   ` [tip:perf/core] tools " tip-bot for Steven Rostedt (VMware)
2018-01-12  0:47 ` [PATCH 03/10] lib traceevent: Print value of unknown symbolic fields Steven Rostedt
2018-01-17 16:28   ` [tip:perf/core] tools " tip-bot for Jan Kiszka
2018-01-12  0:47 ` [PATCH 04/10] lib traceevent: Simplify pointer print logic and fix %pF Steven Rostedt
2018-01-17 16:29   ` [tip:perf/core] tools " tip-bot for Steven Rostedt (VMware)
2018-01-12  0:47 ` Steven Rostedt [this message]
2018-01-17 16:29   ` [tip:perf/core] tools lib traceevent: Handle new pointer processing of bprint strings tip-bot for Steven Rostedt (VMware)
2018-01-12  0:47 ` [PATCH 06/10] lib traceevent: Show contents (in hex) of data of unrecognized type records Steven Rostedt
2018-01-17 16:30   ` [tip:perf/core] tools " tip-bot for Steven Rostedt (VMware)
2018-01-12  0:47 ` [PATCH 07/10] lib traceevent: Use asprintf when possible Steven Rostedt
2018-01-17 16:30   ` [tip:perf/core] tools " tip-bot for Federico Vaga
2018-01-12  0:47 ` [PATCH 08/10] lib traceevent: Add UL suffix to MISSING_EVENTS Steven Rostedt
2018-01-17 16:31   ` [tip:perf/core] tools " tip-bot for Michael Sartain
2018-01-12  0:47 ` [PATCH 09/10] lib traceeevent: Fix missing break in FALSE case of pevent_filter_clear_trivial() Steven Rostedt
2017-04-26 14:55   ` [PATCH] parse-events: Fix the FALSE case in pevent_filter_clear_trivial() Taeung Song
2018-01-17 16:31     ` [tip:perf/core] tools lib traceevent: Fix missing break in FALSE case of pevent_filter_clear_trivial() tip-bot for Taeung Song
2018-01-12  1:00   ` [PATCH 09/10] lib traceeevent: " Taeung Song
2018-01-12  1:14     ` Steven Rostedt
2018-01-12 16:02       ` Arnaldo Carvalho de Melo
2018-01-12  0:47 ` [PATCH 10/10] lib traceevent: Fix get_field_str() for dynamic strings Steven Rostedt
2018-01-17 16:31   ` [tip:perf/core] tools " tip-bot for Steven Rostedt (VMware)
2018-01-17  6:02 ` [PATCH 00/10] tools lib traceveent: Pull updates from trace-cmd library Namhyung Kim
  -- strict thread matches above, loose matches on Subject: below --
2017-10-16 16:55 [PATCH v2 0/4] trace-cmd: Fixes for four minor bugs Michael Sartain
2017-10-16 16:55 ` [PATCH v2 1/4] trace-cmd: Fix incorrect malloc size arg: *item instead of item Michael Sartain
2017-10-16 16:55 ` [PATCH v2 2/4] trace-cmd: Fix NULL pointer being passed to memcpy Michael Sartain
2017-10-16 16:55 ` [PATCH v2 3/4] trace-cmd: Add UL suffix to MISSING_EVENTS since ints shouldn't be left shifted by 31 Michael Sartain
2017-10-16 16:55 ` [PATCH v2 4/4] trace-cmd: Use unsigned values in Hsieh's trace_hash fast hash function Michael Sartain
2017-09-28 20:13 [PATCH][trace-cmd] Print value of unknown symbolic fields Jan Kiszka
2017-10-03 22:46 ` Steven Rostedt
2017-10-03 23:12 ` Steven Rostedt
2017-08-02 22:15 [PATCH V3 1/2] use direname instead of custom code Federico Vaga
2017-08-02 22:15 ` [PATCH V3 2/2] It makes the code clearer and less error prone Federico Vaga
2017-08-14 17:33   ` Steven Rostedt
2017-08-15  7:25     ` Federico Vaga
2017-11-08 18:50       ` Steven Rostedt
2017-08-02 23:48 ` [PATCH V3 1/2] trace-cmd record: use direname instead of custom code Steven Rostedt
2017-08-14 17:14 ` [PATCH V3 1/2] " Steven Rostedt
2017-06-15  0:27 [PATCH v3 0/6] trace-cmd: escape sequence, EINTR, error checking bug fixes Michael Sartain
2017-06-15  0:27 ` [PATCH v3 1/6] Fix bad force_token escape sequence Michael Sartain
2018-01-17 16:28   ` [tip:perf/core] tools lib traceevent: " tip-bot for Michael Sartain
2017-06-15  0:27 ` [PATCH v3 2/6] Fix unsigned return values being error checked as negative Michael Sartain
2017-06-15  0:27 ` [PATCH v3 3/6] Handle EINTR signal interrupts for read, write, open calls Michael Sartain
2017-06-21 13:26   ` Steven Rostedt
2017-06-15  0:27 ` [PATCH v3 4/6] Fix read / write data offsets in read / write loops Michael Sartain
2017-06-21 13:29   ` Steven Rostedt
2017-06-21 17:36     ` Michael Sartain
2017-06-15  0:28 ` [PATCH v3 5/6] Fix function prototypes for __vwarning, __vpr_stat, and __vdie Michael Sartain
2017-06-15  0:28 ` [PATCH v3 6/6] Fix cases where string literals were passed as string format args Michael Sartain

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=20180112004822.403349289@goodmis.org \
    --to=rostedt@goodmis.org \
    --cc=acme@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@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