perf test: Add support for setting objdump binary via perf config

Add a 'perf config' variable that does the same thing as "perf test
--objdump <x>".

Also update the man page.

Committer testing:

  # perf config test.objdump
  # perf test "object code reading"
   26: Object code reading                                             : Ok
  # perf config test.objdump=blah
  # perf config test.objdump
  test.objdump=blah
  # perf test "object code reading"
   26: Object code reading                                             : FAILED!
  # perf test -v "object code reading"
   26: Object code reading                                             :
  --- start ---
  test child forked, pid 600599
  Looking at the vmlinux_path (8 entries long)
  Using /proc/kcore for kernel data
  Using /proc/kallsyms for symbols
  Parsing event 'cycles'
  Using CPUID AuthenticAMD-25-21-0
  mmap size 528384B
  Reading object code for memory address: 0x4d9a02
  File is: /home/acme/bin/perf
  On file address is: 0xd9a02
  Objdump command is: blah -z -d --start-address=0x4d9a02 --stop-address=0x4d9a82 /home/acme/bin/perf
  objdump read too few bytes: 128
  Bytes read differ from those read by objdump
  buf1 (dso):
  0x48 0x85 0xff 0x74 0x29 0xe8 0x94 0xdf 0x07 0x00 0x8b 0x73 0x1c 0x48 0x8b 0x43
  0x08 0xeb 0xa5 0x0f 0x1f 0x00 0x48 0x8b 0x45 0xe8 0x64 0x48 0x2b 0x04 0x25 0x28
  0x00 0x00 0x00 0x75 0x0f 0x48 0x8b 0x5d 0xf8 0xc9 0xc3 0x0f 0x1f 0x00 0x48 0x8b
  0x43 0x08 0xeb 0x84 0xe8 0xc5 0x3e 0xf3 0xff 0x0f 0x1f 0x44 0x00 0x00 0x55 0x48
  0x89 0xe5 0x41 0x56 0x41 0x55 0x49 0x89 0xd5 0x41 0x54 0x49 0x89 0xfc 0x53 0x48
  0x89 0xf3 0x48 0x83 0xec 0x30 0x48 0x8b 0x7e 0x20 0x64 0x48 0x8b 0x04 0x25 0x28
  0x00 0x00 0x00 0x48 0x89 0x45 0xd8 0x31 0xc0 0x48 0x89 0x75 0xb0 0x48 0xc7 0x45
  0xb8 0x00 0x00 0x00 0x00 0x48 0xc7 0x45 0xc0 0x00 0x00 0x00 0x00 0xe8 0xad 0xfa

  buf2 (objdump):
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00

  test child finished with -1
  ---- end ----
  Object code reading: FAILED!
  # perf config test.objdump=/usr/bin/objdump
  # perf config test.objdump
  test.objdump=/usr/bin/objdump
  # perf test "object code reading"
   26: Object code reading                                             : Ok
  #
Signed-off-by: James Clark <james.clark@arm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20231106151051.129440-3-james.clark@arm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-config.txt

@@ -722,6 +722,10 @@ session-<NAME>.*::
 		Defines new record session for daemon. The value is record's
 		command line without the 'record' keyword.
 
+test.*::
+
+	test.objdump::
+		objdump binary to use for disassembly and annotations.
 
 SEE ALSO
 --------

tools/perf/tests/builtin-test.c

@@ -14,6 +14,7 @@
 #include <sys/wait.h>
 #include <sys/stat.h>
 #include "builtin.h"
+#include "config.h"
 #include "hist.h"
 #include "intlist.h"
 #include "tests.h"
@@ -514,6 +515,15 @@ static int run_workload(const char *work, int argc, const char **argv)
 	return -1;
 }
 
+static int perf_test__config(const char *var, const char *value,
+			     void *data __maybe_unused)
+{
+	if (!strcmp(var, "test.objdump"))
+		test_objdump_path = value;
+
+	return 0;
+}
+
 int cmd_test(int argc, const char **argv)
 {
 	const char *test_usage[] = {
@@ -541,6 +551,8 @@ int cmd_test(int argc, const char **argv)
         if (ret < 0)
                 return ret;
 
+	perf_config(perf_test__config, NULL);
+
 	/* Unbuffered output */
 	setvbuf(stdout, NULL, _IONBF, 0);