[PATCH v2 1/4] perf tools: add Java demangling support

Stephane Eranian
2015-02-18T17:24:14Z

Add Java function descriptor demangling support.
Something bfd cannot do.

Use the JAVA_DEMANGLE_NORET flag to avoid decoding the
return type of functions.

Signed-off-by: Stephane Eranian <eranian@google.com>
---
tools/perf/Makefile.perf | 2 +
tools/perf/util/demangle-java.c | 199 ++++++++++++++++++++++++++++++++++++++++
tools/perf/util/demangle-java.h | 10 ++
tools/perf/util/symbol-elf.c | 3 +
tools/perf/util/symbol.c | 6 +-
5 files changed, 219 insertions(+), 1 deletion(-)
create mode 100644 tools/perf/util/demangle-java.c
create mode 100644 tools/perf/util/demangle-java.h

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index aa6a504..53a44be 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -331,6 +331,7 @@ LIB_H += ui/ui.h
LIB_H += util/data.h
LIB_H += util/kvm-stat.h
LIB_H += util/thread-stack.h
+LIB_H += util/demangle-java.h

LIB_OBJS += $(OUTPUT)util/abspath.o
LIB_OBJS += $(OUTPUT)util/alias.o
@@ -410,6 +411,7 @@ LIB_OBJS += $(OUTPUT)util/data.o
LIB_OBJS += $(OUTPUT)util/tsc.o
LIB_OBJS += $(OUTPUT)util/cloexec.o
LIB_OBJS += $(OUTPUT)util/thread-stack.o
+LIB_OBJS += $(OUTPUT)util/demangle-java.o

LIB_OBJS += $(OUTPUT)ui/setup.o
LIB_OBJS += $(OUTPUT)ui/helpline.o
diff --git a/tools/perf/util/demangle-java.c b/tools/perf/util/demangle-java.c
new file mode 100644
index 0000000..79d5484
--- /dev/null
+++ b/tools/perf/util/demangle-java.c
@@ -0,0 +1,199 @@
+#include <sys/types.h>
+#include <stdio.h>
+#include <string.h>
+#include "util.h"
+#include "debug.h"
+#include "symbol.h"
+
+#include "demangle-java.h"
+
+enum {
+ MODE_PREFIX=0,
+ MODE_CLASS=1,
+ MODE_FUNC=2,
+ MODE_TYPE=3,
+ MODE_CTYPE=3, /* class arg */
+};
+
+#define BASE_ENT(c, n) [c-'A']=n
+static const char *base_types['Z'-'A' + 1]={
+ BASE_ENT('B', "byte" ),
+ BASE_ENT('C', "char" ),
+ BASE_ENT('D', "double" ),
+ BASE_ENT('F', "float" ),
+ BASE_ENT('I', "int" ),
+ BASE_ENT('J', "long" ),
+ BASE_ENT('S', "short" ),
+ BASE_ENT('Z', "bool" ),
+};
+
+/*
+ * demangle Java symbol between str and end positions and stores
+ * up to maxlen characters into buf. The parser starts in mode.
+ *
+ * Use MODE_PREFIX to process entire prototype till end position
+ * Use MODE_TYPE to process return type if str starts on return type char
+ *
+ * Return:
+ * success: buf
+ * error : NULL
+ */
+static char *
+__demangle_java_sym(const char *str, const char *end, char *buf, int maxlen, int mode)
+{
+ int rlen = 0;
+ int array = 0;
+ int narg = 0;
+ const char *q;
+
+ if (!end)
+ end = str + strlen(str);
+
+ for (q = str; q != end; q++) {
+
+ if (rlen == (maxlen - 1))
+ break;
+
+ switch (*q) {
+ case 'L':
+ if (mode == MODE_PREFIX || mode == MODE_CTYPE) {
+ if (mode == MODE_CTYPE) {
+ if (narg)
+ rlen += snprintf(buf+rlen, maxlen - rlen, ", ");
+ narg++;
+ }
+ rlen += snprintf(buf+rlen, maxlen - rlen, "class ");
+ if (mode == MODE_PREFIX)
+ mode = MODE_CLASS;
+ } else
+ buf[rlen++] = *q;
+ break;
+ case 'B':
+ case 'C':
+ case 'D':
+ case 'F':
+ case 'I':
+ case 'J':
+ case 'S':
+ case 'Z':
+ if (mode == MODE_TYPE) {
+ if (narg)
+ rlen += snprintf(buf+rlen, maxlen - rlen, ", ");
+ rlen += snprintf(buf+rlen, maxlen - rlen, "%s", base_types[*q - 'A']);
+ while(array--)
+ rlen += snprintf(buf+rlen, maxlen - rlen, "[]");
+ array = 0;
+ narg++;
+ } else
+ buf[rlen++] = *q;
+ break;
+ case 'V':
+ if (mode == MODE_TYPE) {
+ rlen += snprintf(buf+rlen, maxlen - rlen, "void");
+ while(array--)
+ rlen += snprintf(buf+rlen, maxlen - rlen, "[]");
+ array = 0;
+ } else
+ buf[rlen++] = *q;
+ break;
+ case '[':
+ if (mode != MODE_TYPE)
+ goto error;
+ array++;
+ break;
+ case '(':
+ if (mode != MODE_FUNC)
+ goto error;
+ buf[rlen++] = *q;
+ mode = MODE_TYPE;
+ break;
+ case ')':
+ if (mode != MODE_TYPE)
+ goto error;
+ buf[rlen++] = *q;
+ narg = 0;
+ break;
+ case ';':
+ if (mode != MODE_CLASS && mode != MODE_CTYPE)
+ goto error;
+ /* safe because at least one other char to process */
+ if (isalpha(*(q+1)))
+ rlen += snprintf(buf+rlen, maxlen - rlen, ".");
+ if (mode == MODE_CLASS)
+ mode = MODE_FUNC;
+ else if (mode == MODE_CTYPE)
+ mode = MODE_TYPE;
+ break;
+ case '/':
+ if (mode != MODE_CLASS && mode != MODE_CTYPE)
+ goto error;
+ rlen += snprintf(buf+rlen, maxlen - rlen, ".");
+ break;
+ default :
+ buf[rlen++] = *q;
+ }
+ }
+ buf[rlen] = '\0';
+ return buf;
+error:
+ return NULL;
+}
+
+/*
+ * Demangle Java function signature (openJDK, not GCJ)
+ * input:
+ * str: string to parse. String is not modified
+ * flags: comobination of JAVA_DEMANGLE_* flags to modify demangling
+ * return:
+ * if input can be demangled, then a newly allocated string is returned.
+ * if input cannot be demangled, then NULL is returned
+ *
+ * Note: caller is responsible for freeing demangled string
+ */
+char *
+java_demangle_sym(const char *str, int flags)
+{
+ char *buf, *ptr;
+ char *p;
+ size_t len, l1 = 0;
+
+ if (!str)
+ return NULL;
+
+ /* find start of retunr type */
+ p = strrchr(str, ')');
+ if (!p)
+ return NULL;
+
+ /*
+ * expansion factor estimated to 3x
+ */
+ len = strlen(str) * 3 + 1;
+ buf = malloc(len);
+ if (!buf)
+ return NULL;
+
+ buf[0] = '\0';
+ if (!(flags & JAVA_DEMANGLE_NORET)) {
+ /*
+ * get return type first
+ */
+ ptr = __demangle_java_sym(p+1, NULL, buf, len, MODE_TYPE);
+ if (!ptr)
+ goto error;
+
+ /* add space between return type and function prototype */
+ l1 = strlen(buf);
+ buf[l1++] = ' ';
+ }
+
+ /* process function up to return type */
+ ptr = __demangle_java_sym(str, p + 1, buf + l1, len - l1, MODE_PREFIX);
+ if (!ptr)
+ goto error;
+
+ return buf;
+error:
+ free(buf);
+ return NULL;
+}
diff --git a/tools/perf/util/demangle-java.h b/tools/perf/util/demangle-java.h
new file mode 100644
index 0000000..a981c1f
--- /dev/null
+++ b/tools/perf/util/demangle-java.h
@@ -0,0 +1,10 @@
+#ifndef __PERF_DEMANGLE_JAVA
+#define __PERF_DEMANGLE_JAVA 1
+/*
+ * demangle function flags
+ */
+#define JAVA_DEMANGLE_NORET 0x1 /* do not process return type */
+
+char * java_demangle_sym(const char *str, int flags);
+
+#endif /* __PERF_DEMANGLE_JAVA */
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index b24f9d8..73b3e8f 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -6,6 +6,7 @@
#include <inttypes.h>

#include "symbol.h"
+#include "demangle-java.h"
#include "machine.h"
#include "vdso.h"
#include <symbol/kallsyms.h>
@@ -1019,6 +1020,8 @@ int dso__load_sym(struct dso *dso, struct map *map,
demangle_flags = DMGL_PARAMS | DMGL_ANSI;

demangled = bfd_demangle(NULL, elf_name, demangle_flags);
+ if (demangled == NULL)
+ demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
if (demangled != NULL)
elf_name = demangled;
}
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a690668..3bc779b 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -9,6 +9,7 @@
#include <fcntl.h>
#include <unistd.h>
#include <inttypes.h>
+#include <bfd.h>
#include "build-id.h"
#include "util.h"
#include "debug.h"
@@ -1257,6 +1258,7 @@ static int dso__load_perf_map(struct dso *dso, struct map *map,
u64 start, size;
struct symbol *sym;
int line_len, len;
+ char *name;

line_len = getline(&line, &n, file);
if (line_len < 0)
@@ -1279,7 +1281,9 @@ static int dso__load_perf_map(struct dso *dso, struct map *map,
if (len + 2 >= line_len)
continue;

- sym = symbol__new(start, size, STB_GLOBAL, line + len);
+ name = line + len;
+
+ sym = symbol__new(start, size, STB_GLOBAL, name);

if (sym == NULL)
goto out_delete_line;
--
1.9.1