Optionally allow unknown symbols in the backtrace tests

This is useful to test unwinding without debug information. The
binaries being examined might still have frame pointers that allow
us to bridge the unknown symbols.

Signed-off-by: Ulf Hermann <ulf.hermann@qt.io>

3 files changed, 38 insertions, 12 deletions

diff --git a/tests/ChangeLog b/tests/ChangeLog
index 7040ac84..bca47be1 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,5 +1,11 @@
 2017-02-09  Ulf Hermann  <ulf.hermann@qt.io>
 
+	* backtrace.c: Add an option to allow unknown symbols in the trace
+	* backtrace-substr.sh: Add an option to allow unknown symbols
+	to check_core() and allow failed symbol lookups in check_err()
+
+2017-02-09  Ulf Hermann  <ulf.hermann@qt.io>
+
 	* backtrace-data.c: Don't assert that symbols are found.
 	The unwinder is allowed to ask for invalid addresses. We deny
 	such requests, rather than make the test fail.
diff --git a/tests/backtrace-subr.sh b/tests/backtrace-subr.sh
index 790b4f44..5d3937c2 100644
--- a/tests/backtrace-subr.sh
+++ b/tests/backtrace-subr.sh
@@ -44,9 +44,12 @@ check_gsignal()
 # In some cases we cannot reliably find out we got behind _start as some
 # operating system do not properly terminate CFI by undefined PC.
 # Ignore it here as it is a bug of OS, not a bug of elfutils.
+# If the CFI is not terminated correctly, we might find another frame by
+# checking for frame pointers. This is still not our problem, but only
+# gives an error message when trying to look up the function name.
 check_err()
 {
-  if [ $(egrep -v <$1 'dwfl_thread_getframes: (No DWARF information found|no matching address range)$' \
+  if [ $(egrep -v <$1 'dwfl_thread_getframes: (No DWARF information found|no matching address range|address out of range)$' \
          | wc -c) \
        -eq 0 ]
   then
@@ -61,7 +64,9 @@ check_all()
   bt=$1
   err=$2
   testname=$3
-  check_main $bt $testname
+  if [ "x$4" != "x--allow-unknown" ]; then
+    check_main $bt $testname
+  fi
   check_gsignal $bt $testname
   check_err $err $testname
 }
@@ -98,13 +103,14 @@ check_native_unsupported()
 check_core()
 {
   arch=$1
+  args=$2
   testfiles backtrace.$arch.{exec,core}
   tempfiles backtrace.$arch.{bt,err}
   echo ./backtrace ./backtrace.$arch.{exec,core}
-  testrun ${abs_builddir}/backtrace -e ./backtrace.$arch.exec --core=./backtrace.$arch.core 1>backtrace.$arch.bt 2>backtrace.$arch.err || true
+  testrun ${abs_builddir}/backtrace $args -e ./backtrace.$arch.exec --core=./backtrace.$arch.core 1>backtrace.$arch.bt 2>backtrace.$arch.err || true
   cat backtrace.$arch.{bt,err}
   check_unsupported backtrace.$arch.err backtrace.$arch.core
-  check_all backtrace.$arch.{bt,err} backtrace.$arch.core
+  check_all backtrace.$arch.{bt,err} backtrace.$arch.core $args
 }
 
 # Backtrace live process.
diff --git a/tests/backtrace.c b/tests/backtrace.c
index 1ff6353c..34a2ab0b 100644
--- a/tests/backtrace.c
+++ b/tests/backtrace.c
@@ -64,6 +64,7 @@ dump_modules (Dwfl_Module *mod, void **userdata __attribute__ ((unused)),
   return DWARF_CB_OK;
 }
 
+static bool allow_unknown;
 static bool use_raise_jmp_patching;
 static pid_t check_tid;
 
@@ -78,7 +79,8 @@ callback_verify (pid_t tid, unsigned frameno, Dwarf_Addr pc,
     seen_main = true;
   if (pc == 0)
     {
-      assert (seen_main);
+      if (!allow_unknown)
+        assert (seen_main);
       return;
     }
   if (check_tid == 0)
@@ -103,11 +105,12 @@ callback_verify (pid_t tid, unsigned frameno, Dwarf_Addr pc,
 	       && (strcmp (symname, "__kernel_vsyscall") == 0
 		   || strcmp (symname, "__libc_do_syscall") == 0))
 	reduce_frameno = true;
-      else
+      else if (!allow_unknown || symname)
 	assert (symname && strcmp (symname, "raise") == 0);
       break;
     case 1:
-      assert (symname != NULL && strcmp (symname, "sigusr2") == 0);
+      if (!allow_unknown || symname)
+        assert (symname != NULL && strcmp (symname, "sigusr2") == 0);
       break;
     case 2: // x86_64 only
       /* __restore_rt - glibc maybe does not have to have this symbol.  */
@@ -116,20 +119,24 @@ callback_verify (pid_t tid, unsigned frameno, Dwarf_Addr pc,
       if (use_raise_jmp_patching)
 	{
 	  /* Verify we trapped on the very first instruction of jmp.  */
-	  assert (symname != NULL && strcmp (symname, "jmp") == 0);
+          if (!allow_unknown || symname)
+            assert (symname != NULL && strcmp (symname, "jmp") == 0);
 	  mod = dwfl_addrmodule (dwfl, pc - 1);
 	  if (mod)
 	    symname2 = dwfl_module_addrname (mod, pc - 1);
-	  assert (symname2 == NULL || strcmp (symname2, "jmp") != 0);
+          if (!allow_unknown || symname2)
+            assert (symname2 == NULL || strcmp (symname2, "jmp") != 0);
 	  break;
 	}
       /* FALLTHRU */
     case 4:
-      assert (symname != NULL && strcmp (symname, "stdarg") == 0);
+      if (!allow_unknown || symname)
+        assert (symname != NULL && strcmp (symname, "stdarg") == 0);
       break;
     case 5:
       /* Verify we trapped on the very last instruction of child.  */
-      assert (symname != NULL && strcmp (symname, "backtracegen") == 0);
+      if (!allow_unknown || symname)
+        assert (symname != NULL && strcmp (symname, "backtracegen") == 0);
       mod = dwfl_addrmodule (dwfl, pc);
       if (mod)
 	symname2 = dwfl_module_addrname (mod, pc);
@@ -138,7 +145,7 @@ callback_verify (pid_t tid, unsigned frameno, Dwarf_Addr pc,
       // there is no guarantee that the compiler doesn't reorder the
       // instructions or even inserts some padding instructions at the end
       // (which apparently happens on ppc64).
-      if (use_raise_jmp_patching)
+      if (use_raise_jmp_patching && (!allow_unknown || symname2))
         assert (symname2 == NULL || strcmp (symname2, "backtracegen") != 0);
       break;
   }
@@ -424,10 +431,12 @@ exec_dump (const char *exec)
 }
 
 #define OPT_BACKTRACE_EXEC 0x100
+#define OPT_ALLOW_UNKNOWN 0x200
 
 static const struct argp_option options[] =
   {
     { "backtrace-exec", OPT_BACKTRACE_EXEC, "EXEC", 0, N_("Run executable"), 0 },
+    { "allow-unknown", OPT_ALLOW_UNKNOWN, 0, 0, N_("Allow unknown symbols"), 0 },
     { NULL, 0, NULL, 0, NULL, 0 }
   };
 
@@ -445,6 +454,10 @@ parse_opt (int key, char *arg, struct argp_state *state)
       exec_dump (arg);
       exit (0);
 
+    case OPT_ALLOW_UNKNOWN:
+      allow_unknown = true;
+      break;
+
     default:
       return ARGP_ERR_UNKNOWN;
     }
@@ -463,6 +476,7 @@ main (int argc __attribute__ ((unused)), char **argv)
   (void) setlocale (LC_ALL, "");
 
   elf_version (EV_CURRENT);
+  allow_unknown = false;
 
   Dwfl *dwfl = NULL;
   const struct argp_child argp_children[] =