gdb/testsuite/gdb.base/premature-dummy-frame-removal.exp

   1 # Copyright 2021-2024 Free Software Foundation, Inc.
   2
   3 # This program is free software; you can redistribute it and/or modify
   4 # it under the terms of the GNU General Public License as published by
   5 # the Free Software Foundation; either version 3 of the License, or
   6 # (at your option) any later version.
   7 #
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU General Public License for more details.
  12 #
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 # Make an inferior call to a function which uses longjmp.  However,
  17 # the backtrace for the function that is called is broken at the point
  18 # where the longjmp is handled.  This test is checking to see if the
  19 # inferior call still completes successfully.
  20 #
  21 # This test forces a broken backtrace using Python, but in real life a
  22 # broken backtrace can easily occur when calling through code for
  23 # which there is no debug information if the prologue unwinder fails,
  24 # which can often happen if the code has been optimized.
  25 #
  26 # The problem was that, due to the broken backtrace, GDB failed to
  27 # find the inferior call's dummy frame.  GDB then concluded that the
  28 # inferior had longjmp'd backward past the dummy frame and so garbage
  29 # collected the dummy frame, this causes the breakpoint within the
  30 # dummy frame to be deleted.
  31 #
  32 # When the inferior continued, and eventually returned to the dummy
  33 # frame, it would try to execute instruction from the dummy frame
  34 # (which for most, or even all, targets, is on the stack), and then
  35 # experience undefined behaviuor, often a SIGSEGV.
  36
  37 standard_testfile .c
  38
  39 require allow_python_tests
  40
  41 if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
  42     return -1
  43 }
  44
  45 if {![runto_main]} {
  46     return 0
  47 }
  48
  49 set pyfile [gdb_remote_download host ${srcdir}/${subdir}/${testfile}.py]
  50 gdb_test_no_output "source ${pyfile}" "load python file"
  51
  52 gdb_test "p some_func ()" " = 0"
  53
  54 # When frame debugging is turned on, this test has (previously)
  55 # revealed some crashes due to the Python frame unwinder trying to
  56 # read registers.
  57 #
  58 # Enable frame debug and rerun the test.  We don't bother checking the
  59 # output of calling 'p some_func ()' as the output will be full of
  60 # debug, to format of which isn't fixed.  All we care about is that
  61 # GDB is still running afterwards.
  62 #
  63 # All of the debug output makes this really slow when testing with the
  64 # special read1 version of expect, hence the timeout factor.
  65 with_read1_timeout_factor 10 {
  66     gdb_test_no_output "set debug frame on"
  67     gdb_test "p some_func ()" ".*" \
  68         "repeat p some_func () with frame debug on"
  69     gdb_test_no_output "set debug frame off"
  70 }
  71 gdb_test "p 1 + 2 + 3" " = 6"