Home | History | Annotate | Line # | Download | only in gdb.python 
      1 # Copyright (C) 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 # Setup an unwinder that uses gdb.UnwindInfo.add_saved_register with
     17 # the register's 'pc' and 'sp'.  On some (all?) targets, these
     18 # registers are implemented as user-registers, and so can't normally
     19 # be written to directly.
     20 #
     21 # The Python unwinder now includes code similar to how the expression
     22 # evaluator would handle something like 'set $pc=0x1234', we fetch the
     23 # value of '$pc', and then use the value's location to tell us which
     24 # register to write to.
     25 #
     26 # The unwinder defined here deliberately breaks the unwind by setting
     27 # the unwound $pc and $sp to be equal to the current frame's $pc and
     28 # $sp.  GDB will spot this as a loop in the backtrace and terminate
     29 # the unwind.
     30 #
     31 # However, by the time the unwind terminates we have already shown
     32 # that it is possible to call add_saved_register with a user-register,
     33 # so the test is considered passed.
     34 #
     35 # For completeness this test checks two cases, calling
     36 # add_saved_register with a gdb.RegisterDescriptor and calling
     37 # add_saved_register with a string containing the register name.
     38 
     39 load_lib gdb-python.exp
     40 
     41 require allow_python_tests
     42 
     43 standard_testfile
     44 
     45 if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
     46     return -1
     47 }
     48 
     49 if {![runto_main]} {
     50     return 0
     51 }
     52 
     53 set pyfile [gdb_remote_download host ${srcdir}/${subdir}/${testfile}.py]
     54 
     55 gdb_breakpoint [gdb_get_line_number "Break here"]
     56 gdb_continue_to_breakpoint "stop at test breakpoint"
     57 
     58 # Load the script containing the unwinders.  There are actually two
     59 # unwinders defined here that will catch the same function, so we
     60 # immediately disable one of the unwinders.
     61 gdb_test_no_output "source ${pyfile}"\
     62     "import python scripts"
     63 gdb_test "disable unwinder global \"break unwinding using strings\"" \
     64     "1 unwinder disabled" "disable the unwinder that uses strings"
     65 
     66 # At this point we are using the unwinder that passes a
     67 # gdb.RegisterDescriptor to add_saved_register.
     68 gdb_test_sequence "bt"  "Backtrace corrupted by descriptor based unwinder" {
     69     "\\r\\n#0 \[^\r\n\]* foo \\(\\) at "
     70     "\\r\\n#1 \[^\r\n\]* bar \\(\\) at "
     71     "Backtrace stopped: previous frame inner to this frame \\(corrupt stack\\?\\)"
     72 }
     73 
     74 # Disable the unwinder that calls add_saved_register with a
     75 # gdb.RegisterDescriptor, and enable the unwinder that calls
     76 # add_saved_register with a string (containing the register name).
     77 gdb_test "disable unwinder global \"break unwinding using descriptors\"" \
     78     "1 unwinder disabled" "disable the unwinder that uses descriptors"
     79 gdb_test "enable unwinder global \"break unwinding using strings\"" \
     80     "1 unwinder enabled" "enable the unwinder that uses strings"
     81 gdb_test_sequence "bt"  "Backtrace corrupted by string based unwinder" {
     82     "\\r\\n#0 \[^\r\n\]* foo \\(\\) at "
     83     "\\r\\n#1 \[^\r\n\]* bar \\(\\) at "
     84     "Backtrace stopped: previous frame inner to this frame \\(corrupt stack\\?\\)"
     85 }
     86 
     87 # Just for completeness, disable the string unwinder again (neither of
     88 # our special unwinders are now enabled), and check the backtrace.  We
     89 # now get the complete stack back to main.
     90 gdb_test "disable unwinder global \"break unwinding using strings\"" \
     91     "1 unwinder disabled" "disable the unwinder that uses strings again"
     92 gdb_test_sequence "bt"  "Backtrace not corrupted when using no unwinder" {
     93     "\\r\\n#0 \[^\r\n\]* foo \\(\\) at "
     94     "\\r\\n#1 \[^\r\n\]* bar \\(\\) at "
     95     "\\r\\n#2 \[^\r\n\]* main \\(\\) at "
     96 }
     97