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    Subject[tip:perf/core] perf tools: Disable kernel symbol demangling by default
    Commit-ID:  763122ade725592402190f5ff3b8d2edf42b87e8
    Gitweb: http://git.kernel.org/tip/763122ade725592402190f5ff3b8d2edf42b87e8
    Author: Avi Kivity <avi@cloudius-systems.com>
    AuthorDate: Sat, 13 Sep 2014 07:15:05 +0300
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Wed, 17 Sep 2014 17:08:09 -0300

    perf tools: Disable kernel symbol demangling by default

    Some Linux symbols (for example __vt_event_wait) are interpreted by the
    demangler as C++ mangled names, which of course they aren't.

    Disable kernel symbol demangling by default to avoid this, and allow
    enabling it with a new option --demangle-kernel for those who wish it.

    Reported-by: Jiri Olsa <jolsa@redhat.com>
    Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
    Acked-by: Jiri Olsa <jolsa@kernel.org>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Link: http://lkml.kernel.org/r/1410581705-26968-1-git-send-email-avi@cloudius-systems.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/Documentation/perf-probe.txt | 3 +++
    tools/perf/Documentation/perf-report.txt | 3 +++
    tools/perf/Documentation/perf-top.txt | 3 +++
    tools/perf/builtin-probe.c | 2 ++
    tools/perf/builtin-report.c | 2 ++
    tools/perf/builtin-top.c | 2 ++
    tools/perf/util/symbol-elf.c | 7 ++++++-
    tools/perf/util/symbol.c | 1 +
    tools/perf/util/symbol.h | 1 +
    9 files changed, 23 insertions(+), 1 deletion(-)

    diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
    index 1513935..aaa869b 100644
    --- a/tools/perf/Documentation/perf-probe.txt
    +++ b/tools/perf/Documentation/perf-probe.txt
    @@ -104,6 +104,9 @@ OPTIONS
    Specify path to the executable or shared library file for user
    space tracing. Can also be used with --funcs option.

    +--demangle-kernel::
    + Demangle kernel symbols.
    +
    In absence of -m/-x options, perf probe checks if the first argument after
    the options is an absolute path name. If its an absolute path, perf probe
    uses it as a target module/target user space binary to probe.
    diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
    index d561e02..0927bf4 100644
    --- a/tools/perf/Documentation/perf-report.txt
    +++ b/tools/perf/Documentation/perf-report.txt
    @@ -276,6 +276,9 @@ OPTIONS
    Demangle symbol names to human readable form. It's enabled by default,
    disable with --no-demangle.

    +--demangle-kernel::
    + Demangle kernel symbol names to human readable form (for C++ kernels).
    +
    --mem-mode::
    Use the data addresses of samples in addition to instruction addresses
    to build the histograms. To generate meaningful output, the perf.data
    diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
    index 28fdee3..3265b10 100644
    --- a/tools/perf/Documentation/perf-top.txt
    +++ b/tools/perf/Documentation/perf-top.txt
    @@ -98,6 +98,9 @@ Default is to monitor all CPUS.
    --hide_user_symbols::
    Hide user symbols.

    +--demangle-kernel::
    + Demangle kernel symbols.
    +
    -D::
    --dump-symtab::
    Dump the symbol table used for profiling.
    diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
    index 347729e..4d6858d 100644
    --- a/tools/perf/builtin-probe.c
    +++ b/tools/perf/builtin-probe.c
    @@ -376,6 +376,8 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
    "target executable name or path", opt_set_target),
    OPT_BOOLEAN(0, "demangle", &symbol_conf.demangle,
    "Disable symbol demangling"),
    + OPT_BOOLEAN(0, "demangle-kernel", &symbol_conf.demangle_kernel,
    + "Enable kernel symbol demangling"),
    OPT_END()
    };
    int ret;
    diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
    index 3da59a8..8c0b3f2 100644
    --- a/tools/perf/builtin-report.c
    +++ b/tools/perf/builtin-report.c
    @@ -680,6 +680,8 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
    "objdump binary to use for disassembly and annotations"),
    OPT_BOOLEAN(0, "demangle", &symbol_conf.demangle,
    "Disable symbol demangling"),
    + OPT_BOOLEAN(0, "demangle-kernel", &symbol_conf.demangle_kernel,
    + "Enable kernel symbol demangling"),
    OPT_BOOLEAN(0, "mem-mode", &report.mem_mode, "mem access profile"),
    OPT_CALLBACK(0, "percent-limit", &report, "percent",
    "Don't show entries under that percent", parse_percent_limit),
    diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
    index 9848e27..7da2c46 100644
    --- a/tools/perf/builtin-top.c
    +++ b/tools/perf/builtin-top.c
    @@ -1142,6 +1142,8 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
    "Interleave source code with assembly code (default)"),
    OPT_BOOLEAN(0, "asm-raw", &symbol_conf.annotate_asm_raw,
    "Display raw encoding of assembly instructions (default)"),
    + OPT_BOOLEAN(0, "demangle-kernel", &symbol_conf.demangle_kernel,
    + "Enable kernel symbol demangling"),
    OPT_STRING(0, "objdump", &objdump_path, "path",
    "objdump binary to use for disassembly and annotations"),
    OPT_STRING('M', "disassembler-style", &disassembler_style, "disassembler style",
    diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
    index 9fb5e9e..9c9b27f 100644
    --- a/tools/perf/util/symbol-elf.c
    +++ b/tools/perf/util/symbol-elf.c
    @@ -680,6 +680,11 @@ static u64 ref_reloc(struct kmap *kmap)
    return 0;
    }

    +static bool want_demangle(bool is_kernel_sym)
    +{
    + return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
    +}
    +
    int dso__load_sym(struct dso *dso, struct map *map,
    struct symsrc *syms_ss, struct symsrc *runtime_ss,
    symbol_filter_t filter, int kmodule)
    @@ -938,7 +943,7 @@ new_symbol:
    * DWARF DW_compile_unit has this, but we don't always have access
    * to it...
    */
    - if (symbol_conf.demangle) {
    + if (want_demangle(dso->kernel || kmodule)) {
    int demangle_flags = DMGL_NO_OPTS;
    if (verbose)
    demangle_flags = DMGL_PARAMS | DMGL_ANSI;
    diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
    index ac098a3..1adb143 100644
    --- a/tools/perf/util/symbol.c
    +++ b/tools/perf/util/symbol.c
    @@ -34,6 +34,7 @@ struct symbol_conf symbol_conf = {
    .try_vmlinux_path = true,
    .annotate_src = true,
    .demangle = true,
    + .demangle_kernel = false,
    .cumulate_callchain = true,
    .show_hist_headers = true,
    .symfs = "",
    diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
    index 3f95ea0..bec4b7b 100644
    --- a/tools/perf/util/symbol.h
    +++ b/tools/perf/util/symbol.h
    @@ -120,6 +120,7 @@ struct symbol_conf {
    annotate_src,
    event_group,
    demangle,
    + demangle_kernel,
    filter_relative,
    show_hist_headers;
    const char *vmlinux_name,

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