From: Nick Gasson nick.gasson@arm.com
mainline inclusion from mainline-v5.7 commit 0bdf31811be08f93a4bea015d6666df4455c5180 category: bugfix bugzilla: NA CVE: NA
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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 Signed-off-by: Zhichang Yuan erik.yuan@arm.com --- tools/perf/util/demangle-java.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/tools/perf/util/demangle-java.c b/tools/perf/util/demangle-java.c index e4c486756053..c384f66a77fe 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;