linux.git/tools/perf/util/unwind.c, branch master

perf unwind: Refactor get_entries to allow dynamic libdw/libunwind selection

2026-05-15T11:25:02+00:00

Currently, both libdw and libunwind define 'unwind__get_entries'. This
causes a duplicate symbol build failure when both are compiled into
perf.

This commit refactors the DWARF unwind post-processing to be
configurable at runtime via the .perfconfig file option
'unwind.style', or using the argument '--unwind-style' in the commands
'perf report', 'perf script' and 'perf inject', in a similar manner to
the addr2line or the disassembler style.

The file 'tools/perf/util/unwind.c' adds the top-level dispatch
function 'unwind__get_entries'. The backend implementations are
renamed to 'libdw__get_entries' and 'libunwind__get_entries'. Both are
attempted as fallbacks if not configured, or if the primary backend
fails.

Fixes: 2e9191573a69ff96 ("perf build: Remove NO_LIBDW_DWARF_UNWIND option")
Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Albert Ou 
Cc: Alexander Shishkin 
Cc: Alexandre Ghiti 
Cc: Andrew Jones 
Cc: Athira Rajeev 
Cc: Dapeng Mi 
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Florian Fainelli 
Cc: Howard Chu 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Leo Yan 
Cc: libunwind-devel@nongnu.org
Cc: Li Guan 
Cc: Namhyung Kim 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Peter Zijlstra 
Cc: Shimin Guo 
Cc: Thomas Richter 
Cc: Tomas Glozar 
Cc: Will Deacon 
[ Don't mix declarations and code, move 'entries' variable to the start of scope ]
[ Use pr_warning_once() instead of pr_err() in stubs for get_entries(), suggested by a local sashiko instance ]
Signed-off-by: Arnaldo Carvalho de Melo

perf callchain: Separate libunwind code to special object

2014-02-18T12:34:48+00:00

We are going to add libdw library support to do dwarf post unwind.

Making the code ready by moving libunwind dwarf post unwind stuff into
separate object.

Signed-off-by: Jiri Olsa 
Acked-by: Jean Pihet 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1389098853-14466-10-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo

perf callchain: Add mask into struct regs_dump

2014-02-18T12:34:48+00:00

Adding mask info into struct regs_dump to make the registers information
compact.

The mask was always passed along, so logically the mask info fits more
into the struct regs_dump.

Signed-off-by: Jiri Olsa 
Acked-by: Jean Pihet 
Cc: Adrian Hunter 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1389098853-14466-9-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo

perf callchain: Do not report zero address in unwind

2014-02-18T12:34:48+00:00

We are not interested in zero addresses in callchain, do not report
them.

Signed-off-by: Jiri Olsa 
Acked-by: Jean Pihet 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1389098853-14466-8-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Fix dwarf unwind max_stack processing

2014-02-18T12:34:47+00:00

The 'unwind__get_entries' function currently returns 'max_stack + 1'
entries (instead of exact max_stack entries), because max_stack value
does not get decremented for the first entry.

This fix makes dwarf-unwind test pass.

Signed-off-by: Jiri Olsa 
Acked-by: Jean Pihet 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1389098853-14466-7-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Export elf_section_by_name and reuse

2014-01-16T19:29:44+00:00

Remove duplicated elf_section_by_name() functions from unwind.c and
probe-event.c and use one exported elf_section_by_name() instance
defined in symbol-elf.c.

Note that this also moves get_text_start_address() to merge
HAVE_DWARF_SUPPORT defined area.

Reported-by: David Ahern 
Signed-off-by: Masami Hiramatsu 
Cc: "David A. Long" 
Cc: "Steven Rostedt (Red Hat)" 
Cc: David Ahern 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: Oleg Nesterov 
Cc: Srikar Dronamraju 
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20140116093949.24403.38093.stgit@kbuild-fedora.novalocal
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Use the DWARF unwind info only if loaded

2014-01-13T13:06:26+00:00

Use the info only if it has been found in the .debug_frame section of
the ELF binary.

Signed-off-by: Jean Pihet 
Acked-by: Jiri Olsa 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Will Deacon 
Cc: linaro-kernel@lists.linaro.org
Cc: patches@linaro.org
Link: http://lkml.kernel.org/r/1387212194-8028-1-git-send-email-jean.pihet@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Limit max callchain using max_stack on DWARF unwinding too

2013-11-14T19:00:23+00:00

It was affecting only frame-pointer (fp) based callchain processing.

Usage example:

  perf top --call-graph dwarf,1024 --max-stack 2

Works for any tool that does callchain resolving and provides a
--max-stack option.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Mike Galbraith 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Waiman Long 
Link: http://lkml.kernel.org/n/tip-eu45v8s3tq9ruay8tpfyon79@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf: parse the .debug_frame section in case .eh_frame is not present

2013-09-30T15:42:12+00:00

On ARM the debug info is not present in the .eh_frame sections but
in .debug_frame instead, in dwarf format.
Use libunwind to load and parse the debug info.

Dependencies:
 . if present, libunwind >= 1.1 is needed to prevent a segfault when
   parsing the dwarf info,
 . libunwind needs to be configured with --enable-debug-frame. Note:
   --enable-debug-frame is automatically selected on ARM.

Acked-by: Jiri Olsa 
Signed-off-by: Jean Pihet 
Signed-off-by: Will Deacon

perf tools: Remove filter parameter of thread__find_addr_map()

2013-08-12T13:31:12+00:00

Now that the symbol filter is recorded on the machine there is no need
to pass it to thread__find_addr_map().  So remove it.

Signed-off-by: Adrian Hunter 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Mike Galbraith 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/r/1375961547-30267-9-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo