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 <ssanfilippo@chromium.org>
Signed-off-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Stephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-8-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This patch modifies the build dependencies on the jitdump support in
perf. As it stands jitdump was wrongfully made dependent 100% on using
DWARF. However, the dwarf dependency, only exist if generating the
source line table in genelf_debug.c. The rest of the support does not
need DWARF.
This patch removes the dependency on DWARF for the entire jitdump
support. It keeps it only for the genelf_debug.c support.
Signed-off-by: Maciej Debski <maciejd@google.com>
Reviewed-by: Stephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-3-git-send-email-eranian@google.com
Fixes: e12b202f8f ("perf jitdump: Build only on supported archs")
[ Make it build only if NO_LIBELF isn't defined, as jitdump.o will only be built in that case ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Such as CentOS5, where such define is not present in elf.h.
This file, genelf.c, wasn't being built for several systems, because
it mistakenly was conditional on some DWARF features, now that it
is just needing libelf, after "perf jit: Enable jitdump support without
dwarf" it fails.
So, as preparation for "perf jit: Enable jitdump support without dwarf",
conditionally define it, if not available.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Maciej Debski <maciejd@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-k09qay1cmr0l3fzprmztzy3o@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This patch adds source line information support to perf for jitted code.
The source line info must be emitted by the runtime, such as JVMTI.
Perf injects extract the source line info from the jitdump file and adds
the corresponding .debug_lines section in the ELF image generated for
each jitted function.
The source line enables matching any address in the profile with a
source file and line number.
The improvement is visible in perf annotate with the source code
displayed alongside the assembly code.
The dwarf code leverages the support from OProfile which is also
released under GPLv2. Copyright 2007 OProfile authors.
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Carl Love <cel@us.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John McCutchan <johnmccutchan@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sonny Rao <sonnyrao@chromium.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1448874143-7269-5-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This patch adds a --jit/-j option to perf inject.
This options injects MMAP records into the perf.data file to cover the
jitted code mmaps. It also emits ELF images for each function in the
jidump file. Those images are created where the jitdump file is. The
MMAP records point to that location as well.
Typical flow:
$ perf record -k mono -- java -agentpath:libpjvmti.so java_class
$ perf inject --jit -i perf.data -o perf.data.jitted
$ perf report -i perf.data.jitted
Note that jitdump.h support is not limited to Java, it works with any
jitted environment modified to emit the jitdump file format, include
those where code can be jitted multiple times and moved around.
The jitdump.h format is adapted from the Oprofile project.
The genelf.c (ELF binary generation) depends on MD5 hash encoding for
the buildid. To enable this, libssl-dev must be installed. If not, then
genelf.c defaults to using urandom to generate the buildid, which is not
ideal. The Makefile auto-detects the presence on libssl-dev.
This version mmaps the jitdump file to create a marker MMAP record in
the perf.data file. The marker is used to detect jitdump and cause perf
inject to inject the jitted mmaps and generate ELF images for jitted
functions.
In V8, the following fixes and changes were made among other things:
- the jidump header format include a new flags field to be used
to carry information about the configuration of the runtime agent.
Contributed by: Adrian Hunter <adrian.hunter@intel.com>
- Fix mmap pgoff: MMAP event pgoff must be the offset within the ELF file
at which the code resides.
Contributed by: Adrian Hunter <adrian.hunter@intel.com>
- Fix ELF virtual addresses: perf tools expect the ELF virtual addresses of dynamic
objects to match the file offset.
Contributed by: Adrian Hunter <adrian.hunter@intel.com>
- JIT MMAP injection does not obey finished_round semantics. JIT MMAP injection injects all
MMAP events in one go, so it does not obey finished_round semantics, so drop the
finished_round events from the output perf.data file.
Contributed by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Carl Love <cel@us.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John McCutchan <johnmccutchan@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sonny Rao <sonnyrao@chromium.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1448874143-7269-3-git-send-email-eranian@google.com
[ Moved inject.build_ids ordering bits to a separate patch, fixed the NO_LIBELF=1 build ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
