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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Nick Gasson <nick.gasson@arm.com>
Cc: Ian Rogers <irogers@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] perf jvmti: Fix demangling Java symbols
Date: Wed, 27 May 2020 13:23:00 -0300	[thread overview]
Message-ID: <20200527162300.GD16490@kernel.org> (raw)
In-Reply-To: <20200527142057.GF14219@kernel.org>

Em Wed, May 27, 2020 at 11:20:57AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Mon, Apr 27, 2020 at 02:15:16PM +0800, Nick Gasson escreveu:
> > For a Java method signature like:
> > 
> >     Ljava/lang/AbstractStringBuilder;appendChars(Ljava/lang/String;II)V
> > 
> > The demangler produces:
> > 
> >     void class java.lang.AbstractStringBuilder.appendChars(class java.lang., shorttring., int, int)
> > 
> > The arguments should be (java.lang.String, int, int) but the demangler
> > interprets the "S" in String as the type code for "short". Correct this
> > and two other minor things:
> > 
> > - There is no "bool" type in Java, should be "boolean".
> > 
> > - The demangler prepends "class" to every Java class name. This is not
> >   standard Java syntax and it wastes a lot of horizontal space if the
> >   signature is long. Remove this as there isn't any ambiguity between
> >   class names and primitives.
> > 
> > Also added a test case.
> 
> So, I took this and split into a patch for the new 'perf test java' and
> then the fix, so that we can see the problem being detected and then
> apply the fix and see it fixed, the last patch in this series thus
> became:

This is in my tmp.perf/core branch pending a round of testing, after
that it'll move to perf/core on its way to 5.8, thanks.

- Arnaldo
 
> 
> commit 341e11c1d445999932da3f5d626c9fe096949ae3
> Author: Nick Gasson <nick.gasson@arm.com>
> Date:   Mon Apr 27 14:15:16 2020 +0800
> 
>     perf jvmti: Fix demangling Java symbols
>     
>     For a Java method signature like:
>     
>         Ljava/lang/AbstractStringBuilder;appendChars(Ljava/lang/String;II)V
>     
>     The demangler produces:
>     
>         void class java.lang.AbstractStringBuilder.appendChars(class java.lang., shorttring., int, int)
>     
>     The arguments should be (java.lang.String, int, int) but the demangler
>     interprets the "S" in String as the type code for "short". Correct this
>     and two other minor things:
>     
>     - There is no "bool" type in Java, should be "boolean".
>     
>     - The demangler prepends "class" to every Java class name. This is not
>       standard Java syntax and it wastes a lot of horizontal space if the
>       signature is long. Remove this as there isn't any ambiguity between
>       class names and primitives.
>     
>     Committer notes:
>     
>     This was split from a larger patch that also added a java demangler
>     'perf test' entry, that, before this patch shows the error being fixed
>     by it:
>     
>       $ perf test java
>       65: Demangle Java                                         : FAILED!
>       $ perf test -v java
>       Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
>       65: Demangle Java                                         :
>       --- start ---
>       test child forked, pid 307264
>       FAILED: Ljava/lang/StringLatin1;equals([B[B)Z: bool class java.lang.StringLatin1.equals(byte[], byte[]) != boolean java.lang.StringLatin1.equals(byte[], byte[])
>       FAILED: Ljava/util/zip/ZipUtils;CENSIZ([BI)J: long class java.util.zip.ZipUtils.CENSIZ(byte[], int) != long java.util.zip.ZipUtils.CENSIZ(byte[], int)
>       FAILED: Ljava/util/regex/Pattern$BmpCharProperty;match(Ljava/util/regex/Matcher;ILjava/lang/CharSequence;)Z: bool class java.util.regex.Pattern$BmpCharProperty.match(class java.util.regex.Matcher., int, class java.lang., charhar, shortequence) != boolean java.util.regex.Pattern$BmpCharProperty.match(java.util.regex.Matcher, int, java.lang.CharSequence)
>       FAILED: Ljava/lang/AbstractStringBuilder;appendChars(Ljava/lang/String;II)V: void class java.lang.AbstractStringBuilder.appendChars(class java.lang., shorttring., int, int) != void java.lang.AbstractStringBuilder.appendChars(java.lang.String, int, int)
>       FAILED: Ljava/lang/Object;<init>()V: void class java.lang.Object<init>() != void java.lang.Object<init>()
>       test child finished with -1
>       ---- end ----
>       Demangle Java: FAILED!
>       $
>     
>     After applying this patch:
>     
>       $ perf test  java
>       65: Demangle Java                                         : Ok
>       $
>     
>     Signed-off-by: Nick Gasson <nick.gasson@arm.com>
>     Reviewed-by: Ian Rogers <irogers@google.com>
>     Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>     Tested-by: Ian Rogers <irogers@google.com>
>     Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>     Cc: Jiri Olsa <jolsa@redhat.com>
>     Cc: Mark Rutland <mark.rutland@arm.com>
>     Cc: Namhyung Kim <namhyung@kernel.org>
>     Cc: Peter Zijlstra <peterz@infradead.org>
>     Link: http://lore.kernel.org/lkml/20200427061520.24905-4-nick.gasson@arm.com
>     Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> diff --git a/tools/perf/util/demangle-java.c b/tools/perf/util/demangle-java.c
> index 6fb7f34c0814..39c05200ed65 100644
> --- a/tools/perf/util/demangle-java.c
> +++ b/tools/perf/util/demangle-java.c
> @@ -15,7 +15,7 @@ enum {
>  	MODE_CLASS  = 1,
>  	MODE_FUNC   = 2,
>  	MODE_TYPE   = 3,
> -	MODE_CTYPE  = 3, /* class arg */
> +	MODE_CTYPE  = 4, /* class arg */
>  };
>  
>  #define BASE_ENT(c, n)	[c - 'A']=n
> @@ -27,7 +27,7 @@ static const char *base_types['Z' - 'A' + 1] = {
>  	BASE_ENT('I', "int" ),
>  	BASE_ENT('J', "long" ),
>  	BASE_ENT('S', "short" ),
> -	BASE_ENT('Z', "bool" ),
> +	BASE_ENT('Z', "boolean" ),
>  };
>  
>  /*
> @@ -59,15 +59,16 @@ __demangle_java_sym(const char *str, const char *end, char *buf, int maxlen, int
>  
>  		switch (*q) {
>  		case 'L':
> -			if (mode == MODE_PREFIX || mode == MODE_CTYPE) {
> -				if (mode == MODE_CTYPE) {
> +			if (mode == MODE_PREFIX || mode == MODE_TYPE) {
> +				if (mode == MODE_TYPE) {
>  					if (narg)
>  						rlen += scnprintf(buf + rlen, maxlen - rlen, ", ");
>  					narg++;
>  				}
> -				rlen += scnprintf(buf + rlen, maxlen - rlen, "class ");
>  				if (mode == MODE_PREFIX)
>  					mode = MODE_CLASS;
> +				else
> +					mode = MODE_CTYPE;
>  			} else
>  				buf[rlen++] = *q;
>  			break;
> @@ -120,7 +121,7 @@ __demangle_java_sym(const char *str, const char *end, char *buf, int maxlen, int
>  			if (mode != MODE_CLASS && mode != MODE_CTYPE)
>  				goto error;
>  			/* safe because at least one other char to process */
> -			if (isalpha(*(q + 1)))
> +			if (isalpha(*(q + 1)) && mode == MODE_CLASS)
>  				rlen += scnprintf(buf + rlen, maxlen - rlen, ".");
>  			if (mode == MODE_CLASS)
>  				mode = MODE_FUNC;

-- 

- Arnaldo

  reply	other threads:[~2020-05-27 16:23 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-27  6:15 [PATCH 0/3] perf jvmti: Various fixes to JVMTI agent Nick Gasson
2020-04-27  6:15 ` [PATCH 1/3] perf jvmti: Fix jitdump for methods without debug info Nick Gasson
2020-05-14 22:06   ` Ian Rogers
2020-04-27  6:15 ` [PATCH 2/3] perf jvmti: Do not report error when missing debug information Nick Gasson
2020-05-14 22:08   ` Ian Rogers
2020-05-27 14:07   ` Arnaldo Carvalho de Melo
2020-05-27 14:08     ` Arnaldo Carvalho de Melo
2020-04-27  6:15 ` [PATCH 3/3] perf jvmti: Fix demangling Java symbols Nick Gasson
2020-05-14 22:09   ` Ian Rogers
2020-05-27 14:10   ` Arnaldo Carvalho de Melo
2020-05-27 14:20   ` Arnaldo Carvalho de Melo
2020-05-27 16:23     ` Arnaldo Carvalho de Melo [this message]
2020-05-27 22:34       ` Arnaldo Carvalho de Melo
2020-05-28  5:42         ` Nick Gasson
2020-04-27 10:35 ` [PATCH 0/3] perf jvmti: Various fixes to JVMTI agent Jiri Olsa
2020-05-14  8:56   ` Nick Gasson
2020-05-14 13:23     ` Arnaldo Carvalho de Melo
2020-05-14 22:41       ` Ian Rogers
2020-05-15  7:45         ` Nick Gasson

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