Re: [PATCH v3 1/4] perf tools: add Java demangling support

From: Stephane Eranian
Date: Sat Feb 21 2015 - 21:02:28 EST

Next message: Al Viro: "Re: [git pull] more vfs bits"
Previous message: Al Viro: "Re: [git pull] more vfs bits"
In reply to: Namhyung Kim: "Re: [PATCH v3 1/4] perf tools: add Java demangling support"
Next in thread: Stephane Eranian: "[PATCH v3 4/4] perf: Use monotonic clock as a source for timestamps"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Fri, Feb 20, 2015 at 10:17 PM, Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> Hi Stephane,
>
> On Wed, Feb 18, 2015 at 10:40:25PM +0100, Stephane Eranian wrote:
> > 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@xxxxxxxxxx>
> > ---
> > 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
>
> So this still includes the argument (type) right? I just worry about
> that it might fill up the precious screen width of TUI like C++
> symbols did before..
>
>
Yes, because just like C++, argument type are part of signature of the
function. int Foo(int a) vs int Foo(float). Not the same code.

>
> > + * Use MODE_TYPE to process return type if str starts on return type char
>
> What about MODE_CTYPE? I cannot find where it's used..
>
>
CTYPE is ued internally.

>
> > + *
> > + * 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>
>
> Wouldn't it break build on systems don't have the bfd devel package?
> And I don't see why it's needed here..
>
>
I will fix that in v4.

>
> > #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);
>
> I think this file is not a part of this changeset.
>
Removed.

>
> Thanks,
> Namhyung
>
>
> >
> > if (sym == NULL)
> > goto out_delete_line;
> > --
> > 1.9.1
> >
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Al Viro: "Re: [git pull] more vfs bits"
Previous message: Al Viro: "Re: [git pull] more vfs bits"
In reply to: Namhyung Kim: "Re: [PATCH v3 1/4] perf tools: add Java demangling support"
Next in thread: Stephane Eranian: "[PATCH v3 4/4] perf: Use monotonic clock as a source for timestamps"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]