linux.git/tools/perf/util/jitdump.c, branch v4.13

perf str{filter,list}: Disentangle headers

2017-04-19T16:01:52+00:00

There are places where we just need a forward declaration, and others
were we need to include strlist.h and/or strfilter.h, reducing the
impact of changes in headers on the build time, do it.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-zab42gbiki88y9k0csorxekb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Include errno.h where needed

2017-04-19T16:01:51+00:00

Removing it from util.h, part of an effort to disentangle the includes
hell, that makes changes to util.h or something included by it to cause
a complete rebuild of the tools.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-ztrjy52q1rqcchuy3rubfgt2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Move sane ctype stuff from util.h to sane_ctype.h

2017-04-19T16:01:48+00:00

More stuff that came from git, out of the hodge-podge that is util.h

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-e3lana4gctz3ub4hn4y29hkw@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Replace STR() calls with __stringify()

2017-04-19T16:01:47+00:00

Both do the same thing, the later is the one we get from
linux/stringify.h, i.e. we now use the same function name/practice as
the kernel sources.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-w2sxa5o4bfx7fjrd5mu4zmke@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf jit: Check JITHEADER_VERSION

2016-10-24T14:07:40+00:00

Check the version number when opening a jitdump file.  Accept older
versions, but not newer ones.

Signed-off-by: Stefano Sanfilippo 
Signed-off-by: Ross McIlroy 
Reviewed-by: Stephane Eranian 
Cc: Anton Blanchard 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1476356383-30100-9-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jit: Generate .eh_frame/.eh_frame_hdr in DSO

2016-10-24T14:07:40+00:00

When the jit_buf_desc contains unwinding information, it is emitted as
eh_frame unwinding sections in the DSOs generated by perf inject.

The unwinding information is required to unwind of JITed code which do
not maintain the frame pointer register during function calls.  It can
be emitted by V8 / Chromium when the --perf_prof_unwinding_info is
passed to V8.

The eh_frame and eh_frame_hdr sections are emitted immediately after the
.text.

The .eh_frame is aligned at a 8-byte boundary, and .eh_frame_hdr at a
4-byte one. Since size of the .eh_frame is required to be a multiple of
the word size, which means there will never be additional padding
between it and the .eh_frame_hdr on machines where the word size is 4 or
8 bytes.

However, additional padding might be inserted between .text and
.eh_frame to reach the correct alignment, which will always be 8 bytes,
also on 32bit machines. The reasoning behind this choice is that 4 extra
bytes of padding worst case are not a large cost for the advantage of
removing word-size dependent offset calculations when emitting the
jitdump.

Signed-off-by: Stefano Sanfilippo 
Signed-off-by: Ross McIlroy 
Reviewed-by: Stephane Eranian 
Cc: Anton Blanchard 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1476356383-30100-8-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jit: Add unwinding support

2016-10-24T14:07:39+00:00

This record is intended to provide unwinding information in the
eh_frame format. This is required to unwind JITed code which
does not maintain the frame pointer register during function calls.

The eh_frame unwinding information can be emitted by V8 / Chromium
when the --perf_prof_unwinding_info is passed.

A record of type jr_code_unwinding_info comes before the jr_code_load
it referred to and contains both the .eh_frame and .eh_frame_hdr.

The fields in the header have the following meaning:

  * unwinding_size: size of the eh_frame and eh_frame_hdr, necessary
    for distinguishing the content from the padding.

  * eh_frame_hdr_size: as the name says.

  * mapped_size: size of the payload that was in memory at runtime.
    typically unwinding_size if the .eh_frame_hdr and .eh_frame were
    mapped, or 0 if they weren't. It should always be the former case,
    since the .eh_frame is guaranteed to be mapped in memory. However,
    certain JITs might want to inject an .eh_frame_hdr with an empty LUT
    to trigger fp-based unwinding fallback in libunwind. The only part
    of the .eh_frame_hdr that libunwind reads from remote memory is the
    LUT, and since there is none, mapping the unwinding info in memory
    is not necessary, and 0 in this field signifies that it wasn't.
    This practical hack allows to save bytes in code memory for those
    JIT compilers that might or might not maintain a valid frame pointer.

The payload that follows is assumed to contain first the .eh_frame and
then the .eh_header_hdr, with no padding between the two.

Signed-off-by: Stefano Sanfilippo 
Signed-off-by: Ross McIlroy 
Reviewed-by: Stephane Eranian 
Cc: Anton Blanchard 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1476356383-30100-7-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jit: Make perf skip unknown records

2016-10-24T14:07:38+00:00

The behavior before this commit was to skip the remaining portion of the
jitdump in case an unknown record was found, including those records
that perf could handle.

With this change, parsing a record with an unknown id will cause a
warning to be emitted, the record will be skipped and parsing will
resume from the next (valid) one.

The patch aims at making perf more future proof, by extracting as much
information as possible from jitdumps.

Signed-off-by: Stefano Sanfilippo 
Signed-off-by: Ross McIlroy 
Reviewed-by: Stephane Eranian 
Cc: Anton Blanchard 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1476356383-30100-5-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf jit: Avoid returning garbage for a ret variable

2016-10-24T14:07:36+00:00

When the loop body isn't executed at all, then the 'ret' local variable,
that is uninitialized will be used as the return value.

This triggers this error on Alpine Linux:

    CC	   /tmp/build/perf/util/demangle-java.o
    CC	   /tmp/build/perf/util/demangle-rust.o
    CC       /tmp/build/perf/util/jitdump.o
    CC       /tmp/build/perf/util/genelf.o
  util/jitdump.c: In function 'jit_process':
  util/jitdump.c:622:3: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]
     fprintf(stderr, "injected: %s (%d)\n", path, ret);
     ^
  util/jitdump.c:584:6: note: 'ret' was declared here
    int ret;
        ^
    FLEX     /tmp/build/perf/util/parse-events-flex.c

  / $ gcc -v
  Using built-in specs.
  COLLECT_GCC=gcc
  COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-alpine-linux-musl/5.3.0/lto-wrapper
  Target: x86_64-alpine-linux-musl
  Configured with: /home/buildozer/aports/main/gcc/src/gcc-5.3.0/configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info
  +--build=x86_64-alpine-linux-musl --host=x86_64-alpine-linux-musl --target=x86_64-alpine-linux-musl --with-pkgversion='Alpine 5.3.0' --enable-checking=release
  +--disable-fixed-point --disable-libstdcxx-pch --disable-multilib --disable-nls --disable-werror --disable-symvers --enable-__cxa_atexit --enable-esp
  +--enable-cloog-backend --enable-languages=c,c++,objc,java,fortran,ada --disable-libssp --disable-libmudflap --disable-libsanitizer --enable-shared
  +--enable-threads --enable-tls --with-system-zlib
  Thread model: posix
  gcc version 5.3.0 (Alpine 5.3.0)

But this so far got under the radar, not causing any build problem, till the
"perf jit: enable jitdump support without dwarf" gets applied, when the above
problem takes place, some combination of inlining or whatever, the problem
is real, so fix it by initializing the variable to zero.

Cc: Anton Blanchard 
Cc: Jiri Olsa 
Cc: Maciej Debski 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: https://lkml.kernel.org/r/20161013200437.GA12815@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf jitdump: Add the right header to get the major()/minor() definitions

2016-08-15T16:10:28+00:00

Noticed on Fedora Rawhide:

  $ gcc --version
  gcc (GCC) 6.1.1 20160721 (Red Hat 6.1.1-4)
  $ rpm -q glibc
  glibc-2.24.90-1.fc26.x86_64
  $

    CC       /tmp/build/perf/util/jitdump.o
  util/jitdump.c: In function 'jit_repipe_code_load':
  util/jitdump.c:428:2: error: '__major_from_sys_types' is deprecated:
    In the GNU C Library, `major' is defined by .
    For historical compatibility, it is currently defined by
     as well, but we plan to remove this soon.
    To use `major', include  directly.
    If you did not intend to use a system-defined macro `major',
    you should #undef it after including .
    [-Werror=deprecated-declarations]
    event->mmap2.maj   = major(st.st_dev);
    ^~~~~
  In file included from /usr/include/features.h:397:0,
                   from /usr/include/sys/types.h:25,
                   from util/jitdump.c:1:
  /usr/include/sys/sysmacros.h:87:1: note: declared here
   __SYSMACROS_DEFINE_MAJOR (__SYSMACROS_FST_IMPL_TEMPL)

Fix it following that recomendation.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-3majvd0adhfr25rvx4v5e9te@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo