perf tests: objdump output can contain multi byte chunks

objdump's raw insn output can vary across architectures on the number of
bytes per chunk (bpc) displayed and their endianness.

The code-reading test relied on reading objdump output as 1 bpc. Kaixu
Xia reported test failure on ARM64, where objdump displays 4 bpc:

  70c48:        f90027bf         str        xzr, [x29,#72]
  70c4c:        91224000         add        x0, x0, #0x890
  70c50:        f90023a0         str        x0, [x29,#64]

This patch adds support to read raw insn output for any bpc length.
In case of 2+ bpc it also guesses objdump's display endian.

Reported-and-Tested-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/07f0f7bcbda78deb423298708ef9b6a54d6b92bd.1452592712.git.jstancek@redhat.com
[ Fix up pr_fmt() call to use %zd for size_t variables, fixing the build on Ubuntu cross-compiling to armhf and ppc64 ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 68a69a1..2af156a 100644 (file)
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -33,44 +33,86 @@ static unsigned int hex(char c)
        return c - 'A' + 10;
 }
 
-static size_t read_objdump_line(const char *line, size_t line_len, void *buf,
-                             size_t len)
+static size_t read_objdump_chunk(const char **line, unsigned char **buf,
+                                size_t *buf_len)
 {
-       const char *p;
-       size_t i, j = 0;
-
-       /* Skip to a colon */
-       p = strchr(line, ':');
-       if (!p)
-               return 0;
-       i = p + 1 - line;
+       size_t bytes_read = 0;
+       unsigned char *chunk_start = *buf;
 
        /* Read bytes */
-       while (j < len) {
+       while (*buf_len > 0) {
                char c1, c2;
 
-               /* Skip spaces */
-               for (; i < line_len; i++) {
-                       if (!isspace(line[i]))
-                               break;
-               }
                /* Get 2 hex digits */
-               if (i >= line_len || !isxdigit(line[i]))
+               c1 = *(*line)++;
+               if (!isxdigit(c1))
                        break;
-               c1 = line[i++];
-               if (i >= line_len || !isxdigit(line[i]))
+               c2 = *(*line)++;
+               if (!isxdigit(c2))
                        break;
-               c2 = line[i++];
-               /* Followed by a space */
-               if (i < line_len && line[i] && !isspace(line[i]))
+
+               /* Store byte and advance buf */
+               **buf = (hex(c1) << 4) | hex(c2);
+               (*buf)++;
+               (*buf_len)--;
+               bytes_read++;
+
+               /* End of chunk? */
+               if (isspace(**line))
                        break;
-               /* Store byte */
-               *(unsigned char *)buf = (hex(c1) << 4) | hex(c2);
-               buf += 1;
-               j++;
        }
+
+       /*
+        * objdump will display raw insn as LE if code endian
+        * is LE and bytes_per_chunk > 1. In that case reverse
+        * the chunk we just read.
+        *
+        * see disassemble_bytes() at binutils/objdump.c for details
+        * how objdump chooses display endian)
+        */
+       if (bytes_read > 1 && !bigendian()) {
+               unsigned char *chunk_end = chunk_start + bytes_read - 1;
+               unsigned char tmp;
+
+               while (chunk_start < chunk_end) {
+                       tmp = *chunk_start;
+                       *chunk_start = *chunk_end;
+                       *chunk_end = tmp;
+                       chunk_start++;
+                       chunk_end--;
+               }
+       }
+
+       return bytes_read;
+}
+
+static size_t read_objdump_line(const char *line, unsigned char *buf,
+                               size_t buf_len)
+{
+       const char *p;
+       size_t ret, bytes_read = 0;
+
+       /* Skip to a colon */
+       p = strchr(line, ':');
+       if (!p)
+               return 0;
+       p++;
+
+       /* Skip initial spaces */
+       while (*p) {
+               if (!isspace(*p))
+                       break;
+               p++;
+       }
+
+       do {
+               ret = read_objdump_chunk(&p, &buf, &buf_len);
+               bytes_read += ret;
+               p++;
+       } while (ret > 0);
+
        /* return number of successfully read bytes */
-       return j;
+       return bytes_read;
 }
 
 static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
@@ -95,7 +137,7 @@ static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
                }
 
                /* read objdump data into temporary buffer */
-               read_bytes = read_objdump_line(line, ret, tmp, sizeof(tmp));
+               read_bytes = read_objdump_line(line, tmp, sizeof(tmp));
                if (!read_bytes)
                        continue;
 
@@ -152,7 +194,7 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
 
        ret = read_objdump_output(f, buf, &len, addr);
        if (len) {
-               pr_debug("objdump read too few bytes\n");
+               pr_debug("objdump read too few bytes: %zd\n", len);
                if (!ret)
                        ret = len;
        }