linux-kernel - Announcing simple-pt -- a simple Processor Trace implementation for Linux

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 17 Aug 2015 06:31:30 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Announcing simple-pt -- a simple Processor Trace implementation for
 Linux


Modern Intel Core CPUs (5th and 6th generation) have a Intel Processor Trace (PT) feature
to trace branch execution with low overhead. This is useful for performance analysis and debugging.

simple-pt is a simple standalone driver and decoder tool to implement PT on Linux.

Starting with Linux 4.1 Linux has an integrated PT implementation in perf
(see https://lwn.net/Articles/648154/).
simple-pt is an alternative implementation. It has many disadvantages over the perf PT
implementation, such as:
- needs to run as root
- no long term tracing or sampling with interrupts
- no support for interactive debugging (use gdb 7.10 on perf for that)
- no support for histograms
- somewhat experimental
- not as well supported as perf

On the positive side simple-pt is:
- simple
- standalone. No kernel changes needed. Could be ported to older kernels or other operating systems
- easy to modify and experiment with
- more ftrace like decoding tool
- support for kprobes based triggers
- modular “unix style” design with simple tools that do only one thing each
- BSD licensed

Example output:


        % sptcmd  -c tcall taskset -c 0 ./tcall
        cpu   0 offset 1027688,  1003 KB, writing to ptout.0
        ...
        Wrote sideband to ptout.sideband
        % sptdecode --sideband ptout.sideband --pt ptout.0 | less
        TIME      DELTA  INSNs   OPERATION
        frequency 32
        0        [+0]     [+   1] _dl_aux_init+436
                          [+   6] __libc_start_main+455 -> _dl_discover_osversion
        ...
                          [+  13] __libc_start_main+446 -> main
                          [+   9]     main+22 -> f1
                          [+   4]             f1+9 -> f2
                          [+   2]             f1+19 -> f2
                          [+   5]     main+22 -> f1
                          [+   4]             f1+9 -> f2
                          [+   2]             f1+19 -> f2
                          [+   5]     main+22 -> f1
        ...

Available from https://github.com/andikleen/simple-pt

-- 
ak@...ux.intel.com -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/