perf symbol: Add abi::__cxa_demangle C++ demangling support

Refactor C++ demangling out of symbol-elf into its own files similar
to other languages. Add abi::__cxa_demangle support. As the other
demanglers are not shippable with distributions, this brings back C++
demangling in a common case. It isn't perfect as the support for
optionally demangling arguments and modifiers isn't present.

Signed-off-by: Ian Rogers <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Martin Liška <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Pavithra Gurushankar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Quentin Monnet <[email protected]>
Cc: Roberto Sassu <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Tiezhu Yang <[email protected]>
Cc: Tom Rix <[email protected]>
Cc: Yang Jihong <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/Makefile.config

@@ -914,6 +914,7 @@ ifdef BUILD_NONDISTRO
   endif
 
   CFLAGS += -DHAVE_LIBBFD_SUPPORT
+  CXXFLAGS += -DHAVE_LIBBFD_SUPPORT
   ifeq ($(feature-libbfd-buildid), 1)
     CFLAGS += -DHAVE_LIBBFD_BUILDID_SUPPORT
   else
@@ -921,26 +922,24 @@ ifdef BUILD_NONDISTRO
   endif
 endif
 
-ifdef NO_DEMANGLE
-  CFLAGS += -DNO_DEMANGLE
-else
+ifndef NO_DEMANGLE
+  $(call feature_check,cxa-demangle)
+  ifeq ($(feature-cxa-demangle), 1)
+    EXTLIBS += -lstdc++
+    CFLAGS += -DHAVE_CXA_DEMANGLE_SUPPORT
+    CXXFLAGS += -DHAVE_CXA_DEMANGLE_SUPPORT
+  endif
   ifdef BUILD_NONDISTRO
     ifeq ($(filter -liberty,$(EXTLIBS)),)
-      ifdef HAVE_CPLUS_DEMANGLE_SUPPORT
+      $(call feature_check,cplus-demangle)
+      ifeq ($(feature-cplus-demangle), 1)
         EXTLIBS += -liberty
-      else
-        $(call feature_check,cplus-demangle)
-        ifeq ($(feature-cplus-demangle), 1)
-          EXTLIBS += -liberty
-        endif
       endif
     endif
-  endif
-
-  ifneq ($(filter -liberty,$(EXTLIBS)),)
-    CFLAGS += -DHAVE_CPLUS_DEMANGLE_SUPPORT
-  else
-    CFLAGS += -DNO_DEMANGLE
+    ifneq ($(filter -liberty,$(EXTLIBS)),)
+      CFLAGS += -DHAVE_CPLUS_DEMANGLE_SUPPORT
+      CXXFLAGS += -DHAVE_CPLUS_DEMANGLE_SUPPORT
+    endif
   endif
 endif
 

tools/perf/util/Build

@@ -211,6 +211,7 @@ perf-$(CONFIG_ZSTD) += zstd.o
 
 perf-$(CONFIG_LIBCAP) += cap.o
 
+perf-y += demangle-cxx.o
 perf-y += demangle-ocaml.o
 perf-y += demangle-java.o
 perf-y += demangle-rust.o

tools/perf/util/demangle-cxx.cpp

@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "demangle-cxx.h"
+#include <stdlib.h>
+#include <string.h>
+#include <linux/compiler.h>
+
+#ifdef HAVE_LIBBFD_SUPPORT
+#define PACKAGE 'perf'
+#include <bfd.h>
+#endif
+
+#ifdef HAVE_CXA_DEMANGLE_SUPPORT
+#include <cxxabi.h>
+#endif
+
+#if defined(HAVE_LIBBFD_SUPPORT) || defined(HAVE_CPLUS_DEMANGLE_SUPPORT)
+#ifndef DMGL_PARAMS
+#define DMGL_PARAMS     (1 << 0)  /* Include function args */
+#define DMGL_ANSI       (1 << 1)  /* Include const, volatile, etc */
+#endif
+#endif
+
+/*
+ * Demangle C++ function signature
+ *
+ * Note: caller is responsible for freeing demangled string
+ */
+extern "C"
+char *cxx_demangle_sym(const char *str, bool params __maybe_unused,
+                       bool modifiers __maybe_unused)
+{
+#ifdef HAVE_LIBBFD_SUPPORT
+        int flags = (params ? DMGL_PARAMS : 0) | (modifiers ? DMGL_ANSI : 0);
+
+        return bfd_demangle(NULL, str, flags);
+#elif defined(HAVE_CPLUS_DEMANGLE_SUPPORT)
+        int flags = (params ? DMGL_PARAMS : 0) | (modifiers ? DMGL_ANSI : 0);
+
+        return cplus_demangle(str, flags);
+#elif defined(HAVE_CXA_DEMANGLE_SUPPORT)
+        size_t len = strlen(str);
+        char *output = (char*)malloc(len);
+        int status;
+
+        output = abi::__cxa_demangle(str, output, &len, &status);
+        return output;
+#else
+        return NULL;
+#endif
+}

tools/perf/util/demangle-cxx.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_DEMANGLE_CXX
+#define __PERF_DEMANGLE_CXX 1
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+char *cxx_demangle_sym(const char *str, bool params, bool modifiers);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif /* __PERF_DEMANGLE_CXX */

tools/perf/util/symbol-elf.c

@@ -12,6 +12,7 @@
 #include "maps.h"
 #include "symbol.h"
 #include "symsrc.h"
+#include "demangle-cxx.h"
 #include "demangle-ocaml.h"
 #include "demangle-java.h"
 #include "demangle-rust.h"
@@ -25,6 +26,11 @@
 #include <symbol/kallsyms.h>
 #include <internal/lib.h>
 
+#ifdef HAVE_LIBBFD_SUPPORT
+#define PACKAGE 'perf'
+#include <bfd.h>
+#endif
+
 #ifndef EM_AARCH64
 #define EM_AARCH64	183  /* ARM 64 bit */
 #endif
@@ -45,34 +51,6 @@
 
 typedef Elf64_Nhdr GElf_Nhdr;
 
-#ifndef DMGL_PARAMS
-#define DMGL_NO_OPTS     0              /* For readability... */
-#define DMGL_PARAMS      (1 << 0)       /* Include function args */
-#define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */
-#endif
-
-#ifdef HAVE_LIBBFD_SUPPORT
-#define PACKAGE 'perf'
-#include <bfd.h>
-#else
-#ifdef HAVE_CPLUS_DEMANGLE_SUPPORT
-extern char *cplus_demangle(const char *, int);
-
-static inline char *bfd_demangle(void __maybe_unused *v, const char *c, int i)
-{
-	return cplus_demangle(c, i);
-}
-#else
-#ifdef NO_DEMANGLE
-static inline char *bfd_demangle(void __maybe_unused *v,
-				 const char __maybe_unused *c,
-				 int __maybe_unused i)
-{
-	return NULL;
-}
-#endif
-#endif
-#endif
 
 #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
 static int elf_getphdrnum(Elf *elf, size_t *dst)
@@ -295,7 +273,6 @@ static bool want_demangle(bool is_kernel_sym)
 
 static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
 {
-	int demangle_flags = verbose > 0 ? (DMGL_PARAMS | DMGL_ANSI) : DMGL_NO_OPTS;
 	char *demangled = NULL;
 
 	/*
@@ -306,7 +283,7 @@ static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
 	if (!want_demangle(dso->kernel || kmodule))
 	    return demangled;
 
-	demangled = bfd_demangle(NULL, elf_name, demangle_flags);
+	demangled = cxx_demangle_sym(elf_name, verbose > 0, verbose > 0);
 	if (demangled == NULL) {
 		demangled = ocaml_demangle_sym(elf_name);
 		if (demangled == NULL) {