Commit 0bdf3181 authored by Nick Gasson's avatar Nick Gasson Committed by Arnaldo Carvalho de Melo

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: default avatarNick Gasson <nick.gasson@arm.com>
Reviewed-by: default avatarIan Rogers <irogers@google.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: default avatarIan 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.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 525c821d
...@@ -15,7 +15,7 @@ enum { ...@@ -15,7 +15,7 @@ enum {
MODE_CLASS = 1, MODE_CLASS = 1,
MODE_FUNC = 2, MODE_FUNC = 2,
MODE_TYPE = 3, MODE_TYPE = 3,
MODE_CTYPE = 3, /* class arg */ MODE_CTYPE = 4, /* class arg */
}; };
#define BASE_ENT(c, n) [c - 'A']=n #define BASE_ENT(c, n) [c - 'A']=n
...@@ -27,7 +27,7 @@ static const char *base_types['Z' - 'A' + 1] = { ...@@ -27,7 +27,7 @@ static const char *base_types['Z' - 'A' + 1] = {
BASE_ENT('I', "int" ), BASE_ENT('I', "int" ),
BASE_ENT('J', "long" ), BASE_ENT('J', "long" ),
BASE_ENT('S', "short" ), 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 ...@@ -59,15 +59,16 @@ __demangle_java_sym(const char *str, const char *end, char *buf, int maxlen, int
switch (*q) { switch (*q) {
case 'L': case 'L':
if (mode == MODE_PREFIX || mode == MODE_CTYPE) { if (mode == MODE_PREFIX || mode == MODE_TYPE) {
if (mode == MODE_CTYPE) { if (mode == MODE_TYPE) {
if (narg) if (narg)
rlen += scnprintf(buf + rlen, maxlen - rlen, ", "); rlen += scnprintf(buf + rlen, maxlen - rlen, ", ");
narg++; narg++;
} }
rlen += scnprintf(buf + rlen, maxlen - rlen, "class ");
if (mode == MODE_PREFIX) if (mode == MODE_PREFIX)
mode = MODE_CLASS; mode = MODE_CLASS;
else
mode = MODE_CTYPE;
} else } else
buf[rlen++] = *q; buf[rlen++] = *q;
break; break;
...@@ -120,7 +121,7 @@ __demangle_java_sym(const char *str, const char *end, char *buf, int maxlen, int ...@@ -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) if (mode != MODE_CLASS && mode != MODE_CTYPE)
goto error; goto error;
/* safe because at least one other char to process */ /* 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, "."); rlen += scnprintf(buf + rlen, maxlen - rlen, ".");
if (mode == MODE_CLASS) if (mode == MODE_CLASS)
mode = MODE_FUNC; mode = MODE_FUNC;
......
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