Date:	Mon, 17 Feb 2014 15:28:00 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>, linux-kernel@...r.kernel.org,
	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	"David A. Long" <dave.long@...aro.org>,
	yrl.pp-manager.tt@...achi.com, Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH -tip v3 00/11] perf-probe: Updates for handling local
 functions correctly and distro debuginfo

Em Fri, Feb 14, 2014 at 02:43:12PM +0900, Masami Hiramatsu escreveu:
> Ping? :)

One patch didn't apply, 10/11, and it does't passes the build tests,
please try this before submitting patches:

[acme@zoo linux]$ make -C tools/perf build-test
make: Entering directory `/home/git/linux/tools/perf'
- make_pure: cd . && make -f Makefile DESTDIR=/tmp/tmp.yQDeWAV994 
make[1]: *** [make_pure] Error 1
make: *** [build-test] Error 2
make: Leaving directory `/home/git/linux/tools/perf'
[acme@zoo linux]$`

Failed the first test, to check what was that failed, do this:

[acme@zoo linux]$ tail -9 tools/perf/make_pure 
gcc -o ui/helpline.o -c  -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat-y2k -Winit-self -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-system-headers -Wold-style-definition -Wpacked -Wredundant-decls -Wshadow -Wstrict-aliasing=3 -Wstrict-prototypes -Wswitch-default -Wswitch-enum -Wundef -Wwrite-strings -Wformat -DHAVE_ARCH_X86_64_SUPPORT -DHAVE_PERF_REGS_SUPPORT -Werror -O6 -fno-omit-frame-pointer -ggdb3 -funwind-tables -Wall -Wextra -std=gnu99 -fstack-protector-all -D_FORTIFY_SOURCE=2 -I/home/git/linux/tools/perf/util/include -I/home/git/linux/tools/perf/arch/x86/include -I/home/git/linux/tools/include/ -I/home/git/linux/arch/x86/include/uapi -I/home/git/linux/arch/x86/include -I/home/git/linux/include/uapi -I/home/git/linux/include -I/home/git/linux/tools/perf/util -I/home/git/linux/tools/perf -I/home/git/linux/tools/lib/ -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -DHAVE_LIBELF_SUPPORT -DHAVE_LIBELF_MMAP_SUPPORT -DHAVE_ELF_GETPHDRNUM_SUPPORT -DHAVE_DWARF_SUPPORT  -DNO_LIBUNWIND_DEBUG_FRAME -DHAVE_DWARF_UNWIND_SUPPORT -DHAVE_LIBUNWIND_SUPPORT  -DHAVE_LIBAUDIT_SUPPORT -I/usr/include/slang -DHAVE_SLANG_SUPPORT -DHAVE_GTK2_SUPPORT -DHAVE_TIMERFD_SUPPORT -DHAVE_LIBBFD_SUPPORT -DHAVE_ON_EXIT_SUPPORT -DHAVE_BACKTRACE_SUPPORT -DHAVE_LIBNUMA_SUPPORT ui/helpline.c
util/probe-event.c: In function ‘add_exec_to_probe_trace_events’:
util/probe-event.c:369:3: error: ‘offset’ undeclared (first use in this function)
util/probe-event.c:369:3: note: each undeclared identifier is reported only once for each function it appears in
util/probe-event.c:373:20: error: ‘buf’ undeclared (first use in this function)
make[3]: *** [util/probe-event.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [all] Error 2
  test: test -x ./perf
[acme@zoo linux]$

So that lots of tests with multiple combos of features are performed.

Thanks,

- Arnaldo
 
> (2014/02/06 14:32), Masami Hiramatsu wrote:
> > Hi,
> > 
> > Here is the 3rd version of the series for handling local
> > functions correctly with perf-probe. This version also
> > includes distro debuginfo-file support (a small
> > enhancement, based on existing feature).
> > 
> > In this version, I used ref_reloc_sym based probe point
> > instead of absolute address/"_stext", because kASLR
> > changes the address offset randomly and the debuginfo
> > doesn't know that offset. Recently perftools supports
> > kASLR by introducing ref_reloc_sym (which is usually
> > "_text" or "_stext"). Since we already ensured that
> > the kmap->ref_reloc_sym symbol exists in the kernel,
> > it is safe to reuse it for the reference point of
> > probe points.
> > 
> > Note that this series requires a bugfix patch:
> >   perf-probe: Do not add offset to uprobe address
> >   https://lkml.org/lkml/2014/2/5/7
> > 
> > 
> > Issue 1)
> >  Current perf-probe can't handle probe-points for kprobes,
> >  since it uses symbol-based probe definition. The symbol
> >  based definition is easy to read and robust for differnt
> >  kernel and modules. However, when user gives a local
> >  function name which has several different instances,
> >  it may put probes on wrong (or unexpected) address.
> >  On the other hand, since uprobe events are based on the
> >  actual address, it can avoid this issue.
> > 
> >  E.g.
> > In the case to probe t_show local functions (which has
> > 4 different instances.
> >   ----
> >   # grep " t_show\$" /proc/kallsyms
> >   ffffffff810d9720 t t_show
> >   ffffffff810e2e40 t t_show
> >   ffffffff810ece30 t t_show
> >   ffffffff810f4ad0 t t_show
> >   # ./perf probe -fa "t_show \$vars"
> >   Added new events:
> >     probe:t_show         (on t_show with $vars)
> >     probe:t_show_1       (on t_show with $vars)
> >     probe:t_show_2       (on t_show with $vars)
> >     probe:t_show_3       (on t_show with $vars)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> >           perf record -e probe:t_show_3 -aR sleep 1
> >   ----
> > OK, we have 4 different t_show()s. All functions have
> > different arguments as below;
> >   ----
> >   # cat /sys/kernel/debug/tracing/kprobe_events
> >   p:probe/t_show t_show m=%di:u64 v=%si:u64
> >   p:probe/t_show_1 t_show m=%di:u64 v=%si:u64 t=%si:u64
> >   p:probe/t_show_2 t_show m=%di:u64 v=%si:u64 fmt=%si:u64
> >   p:probe/t_show_3 t_show m=%di:u64 v=%si:u64 file=%si:u64
> >   ----
> > However, all of them have been put on the *same* address.
> >   ----
> >   # cat /sys/kernel/debug/kprobes/list
> >   ffffffff810d9720  k  t_show+0x0    [DISABLED]
> >   ffffffff810d9720  k  t_show+0x0    [DISABLED]
> >   ffffffff810d9720  k  t_show+0x0    [DISABLED]
> >   ffffffff810d9720  k  t_show+0x0    [DISABLED]
> >   ----
> >  oops...
> > 
> > Issue 2)
> >  With the debuginfo, issue 1 can be solved by using
> >  _stext-based probe definition instead of local symbol-based.
> >  However, without debuginfo, perf-probe can only use
> >  symbol-map in the binary (or kallsyms). The map provides
> >  symbol find methods, but it returns only the first matched
> >  symbol. To put probes on all functions which have given
> >  symbol, we need a symbol-list iterator for the map.
> > 
> >  E.g. (built perf with NO_DWARF=1)
> > In the case to probe t_show and identity__map_ip in perf.
> >   ----
> >   # ./perf probe -a t_show
> >   Added new event:
> >     probe:t_show         (on t_show)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> >           perf record -e probe:t_show -aR sleep 1
> > 
> >   # ./perf probe -x perf -a identity__map_ip
> >   no symbols found in /kbuild/ksrc/linux-3/tools/perf/perf, maybe install a debug package?
> >   Failed to load map.
> >     Error: Failed to add events. (-22)
> >   ----
> >  oops.....
> > 
> > 
> > Solutions)
> > To solve the issue 1, this series changes perf probe to
> > use _stext-based probe definition. This means that we
> > also need to fix the --list options to analyze actual
> > probe address from _stext address. (and that has been
> > done in this series).
> > 
> > E.g. with this series;
> >   ----
> >   # ./perf probe -a "t_show \$vars"
> >   Added new events:
> >     probe:t_show         (on t_show with $vars)
> >     probe:t_show_1       (on t_show with $vars)
> >     probe:t_show_2       (on t_show with $vars)
> >     probe:t_show_3       (on t_show with $vars)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> >           perf record -e probe:t_show_3 -aR sleep 1
> > 
> >   # cat /sys/kernel/debug/tracing/kprobe_events
> >   p:probe/t_show _stext+889880 m=%di:u64 v=%si:u64
> >   p:probe/t_show_1 _stext+928568 m=%di:u64 v=%si:u64 t=%si:u64
> >   p:probe/t_show_2 _stext+969512 m=%di:u64 v=%si:u64 fmt=%si:u64
> >   p:probe/t_show_3 _stext+1001416 m=%di:u64 v=%si:u64 file=%si:u64
> > 
> >   # cat /sys/kernel/debug/kprobes/list
> >   ffffffffb50d95e0  k  t_show+0x0    [DISABLED]
> >   ffffffffb50e2d00  k  t_show+0x0    [DISABLED]
> >   ffffffffb50f4990  k  t_show+0x0    [DISABLED]
> >   ffffffffb50eccf0  k  t_show+0x0    [DISABLED]
> >   ----
> > This time we can see the events are set in different
> > addresses.
> > 
> > And for the issue 2, the last patch introduces symbol
> > iterators for map, dso and symbols (since the symbol
> > list is the symbols and it is included in dso, and perf
> > probe accesses dso via map).
> > 
> > E.g. with this series (built perf with NO_DWARF=1);
> >   ----
> >   # ./perf probe -a t_show
> >   Added new events:
> >     probe:t_show         (on t_show)
> >     probe:t_show_1       (on t_show)
> >     probe:t_show_2       (on t_show)
> >     probe:t_show_3       (on t_show)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> >           perf record -e probe:t_show_3 -aR sleep 1
> > 
> >   # ./perf probe -x perf -a identity__map_ip
> >   Added new events:
> >     probe_perf:identity__map_ip (on identity__map_ip in /kbuild/ksrc/linux-3/tools/perf/perf)
> >     probe_perf:identity__map_ip_1 (on identity__map_ip in /kbuild/ksrc/linux-3/tools/perf/perf)
> >     probe_perf:identity__map_ip_2 (on identity__map_ip in /kbuild/ksrc/linux-3/tools/perf/perf)
> >     probe_perf:identity__map_ip_3 (on identity__map_ip in /kbuild/ksrc/linux-3/tools/perf/perf)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> >           perf record -e probe_perf:identity__map_ip_3 -aR sleep 1
> >   ----
> > Now, even without the debuginfo, both the kprobe and
> > uprobe are set 4 different places correctly.
> > 
> > BTW, while testing above, I've found some bugs and
> > another minor issue; perf-probe doesn't show the
> > modules and binaries in which probes are set.
> > I've also fixed it in this series as below.
> > 
> > Without the fix;
> > 
> >   # ./perf probe -m drm drm_av_sync_delay
> >   # ./perf probe -x perf dso__load_vmlinux
> > 
> >   # ./perf probe -l
> >     probe:drm_av_sync_delay (on drm_av_sync_delay)
> >     probe_perf:dso__load_vmlinux (on 0x000000000006d110)
> > 
> > With this fix;
> > 
> >   # ./perf probe -l
> >     probe:drm_av_sync_delay (on drm_av_sync_delay in drm)
> >     probe_perf:dso__load_vmlinux (on 0x000000000006d110 in /kbuild/ksrc/linux-3/tools/perf/perf)
> > 
> > Changes from v2:
> >  - Use ref_reloc_sym instead of "_stext" for reference point.
> >    (Thanks for Namhyung Kim!)
> >  - Add 2 cleanup patches for reducing the redundant features.
> >  - Add distro-style debuginfo support.
> > 
> > TODO:
> >  - Support local functions in modules. This requires kernel
> >  side enhancement to allow setting probes by the relative
> >  addresses in modules too.
> >  - Uprobe-event MUST traces the change of given binary even
> >  when the event is disabled. I've found that user can replace
> >  the target binary after setting events and the events can be
> >  enabled on the different instructions...
> > 
> > ---
> > 
> > Masami Hiramatsu (11):
> >       [BUGFIX] perf-probe: Fix to do exit call for symbol maps
> >       [CLEANUP] perf-probe: Remove incorrect symbol check for --list
> >       [CLEANUP] perf-probe: Replace line_list with intlist
> >       [CLEANUP] perf-probe: Unify show_available_functions for uprobes/kprobes
> >       perf-probe: Show in what binaries/modules probes are set
> >       perf-probe: Use ref_reloc_sym based address instead of the symbol name
> >       perf-probe: Find given address from offline dwarf
> >       perf-probe: Show appropriate symbol for ref_reloc_sym based kprobes
> >       perf-probe: Show source-level or symbol-level info for uprobes
> >       perf-probe: Allow to add events on the local functions
> >       perf probe: Support distro-style debuginfo for uprobe
> > 
> > 
> >  tools/perf/builtin-probe.c     |   12 -
> >  tools/perf/util/dso.h          |   10 
> >  tools/perf/util/map.h          |   10 
> >  tools/perf/util/probe-event.c  |  863 ++++++++++++++++++++++------------------
> >  tools/perf/util/probe-event.h  |   12 -
> >  tools/perf/util/probe-finder.c |  198 ++-------
> >  tools/perf/util/probe-finder.h |    5 
> >  tools/perf/util/symbol.h       |   11 +
> >  8 files changed, 566 insertions(+), 555 deletions(-)
> > 
> 
> 
> -- 
> Masami HIRAMATSU
> IT Management Research Dept. Linux Technology Center
> Hitachi, Ltd., Yokohama Research Laboratory
> E-mail: masami.hiramatsu.pt@...achi.com
> 
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