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>

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 1513935..aaa869b 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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,