From 0c92d8c1c34359a02073b9b3ec19956841b232b2 Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Thu, 16 Aug 2012 15:45:46 +0000 Subject: [PATCH] DWARF frame unwinder executes one too many rows The problem is trying to unwind from a function where %ebp is NOT used as the frame pointer, and the size of the frame changes over the lifetime of that function. For instance, trying to unwind past the GNAT runtime function called system.tasking.rendezvous.timed_selective_wait on x86-linux, one can get: (gdb) bt [...] #3 0x0805364b in system.tasking.rendezvous.timed_selective_wait () #4 0xb7fe5068 in ?? () Backtrace stopped: previous frame inner to this frame (corrupt stack?) Looking at the CFI, we find the following initial instructions... > DW_CFA_def_cfa: %esp+4 (r4 ofs 4) > DW_CFA_offset: %eip at cfa-4 (r8 = %eip) ... and the associated FDE: > 00001be4 00000054 00001be8 FDE cie=00000000 pc=08053310..08053951 [...] > DW_CFA_advance_loc: 8 to 080534ad > DW_CFA_def_cfa_offset: 112 > DW_CFA_advance_loc2: 414 to 0805364b > DW_CFA_def_cfa_offset: 108 [...] The problem is that the DWARF frame unwinder executed the FDE until the row for PC == 0x0805364b. But in reality, our program hasn't executed the instruction at that address yet (it is the return address). So GDB executed a little too much of the FDE, giving us the wrong offset for the frame base, and thus the wrong address where %eip got saved. This patch fixes the problem by using a more correct PC as the bound for executing the FDE. gdb/ChangeLog: * dwarf2-frame.c (dwarf2_frame_cache): Use get_frame_address_in_block instead of get_frame_pc as the bound for executing the frame's FDE. gdb/testsuite/ChangeLog: * gdb.ada/rdv_wait: New testcase. --- gdb/ChangeLog | 6 +++ gdb/dwarf2-frame.c | 5 ++- gdb/testsuite/ChangeLog | 4 ++ gdb/testsuite/gdb.ada/rdv_wait.exp | 32 ++++++++++++++++ gdb/testsuite/gdb.ada/rdv_wait/foo.adb | 53 ++++++++++++++++++++++++++ gdb/testsuite/gdb.ada/rdv_wait/pck.adb | 23 +++++++++++ gdb/testsuite/gdb.ada/rdv_wait/pck.ads | 22 +++++++++++ 7 files changed, 143 insertions(+), 2 deletions(-) create mode 100644 gdb/testsuite/gdb.ada/rdv_wait.exp create mode 100644 gdb/testsuite/gdb.ada/rdv_wait/foo.adb create mode 100644 gdb/testsuite/gdb.ada/rdv_wait/pck.adb create mode 100644 gdb/testsuite/gdb.ada/rdv_wait/pck.ads diff --git a/gdb/ChangeLog b/gdb/ChangeLog index fd04d7ada55..3c83d5d8d67 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2012-08-16 Joel Brobecker + + * dwarf2-frame.c (dwarf2_frame_cache): Use + get_frame_address_in_block instead of get_frame_pc as + the bound for executing the frame's FDE. + 2012-08-16 Yao Qi * gdbtypes.h (enum type_code): Define TYPE_CODE_BITSTRING -1. diff --git a/gdb/dwarf2-frame.c b/gdb/dwarf2-frame.c index 986aaea2335..dcfbeb7be59 100644 --- a/gdb/dwarf2-frame.c +++ b/gdb/dwarf2-frame.c @@ -1065,7 +1065,8 @@ dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache) /* First decode all the insns in the CIE. */ execute_cfa_program (fde, fde->cie->initial_instructions, - fde->cie->end, gdbarch, get_frame_pc (this_frame), fs); + fde->cie->end, gdbarch, + get_frame_address_in_block (this_frame), fs); /* Save the initialized register set. */ fs->initial = fs->regs; @@ -1090,7 +1091,7 @@ dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache) /* Then decode the insns in the FDE up to our target PC. */ execute_cfa_program (fde, instr, fde->end, gdbarch, - get_frame_pc (this_frame), fs); + get_frame_address_in_block (this_frame), fs); TRY_CATCH (ex, RETURN_MASK_ERROR) { diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index f15d8c7c611..9c80ecbc925 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2012-08-16 Joel Brobecker + + * gdb.ada/rdv_wait: New testcase. + 2012-08-14 Jan Kratochvil * gdb.base/attach-twice.exp: Remove excessive ps exec. diff --git a/gdb/testsuite/gdb.ada/rdv_wait.exp b/gdb/testsuite/gdb.ada/rdv_wait.exp new file mode 100644 index 00000000000..67e0f1e8bad --- /dev/null +++ b/gdb/testsuite/gdb.ada/rdv_wait.exp @@ -0,0 +1,32 @@ +# Copyright 2012 Free Software Foundation, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +load_lib "ada.exp" + +standard_ada_testfile foo + +if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } { + return -1 +} + +clean_restart ${testfile} + +runto "break_me" + +# Switch to task 2, and verify that GDB is able to unwind all the way +# to foo.T. +gdb_test "task 2" \ + [join {"\\\[Switching to task 2\\\].*" \ + ".*foo\\.t \\(.*\\).*foo\\.adb:.*"} ""] diff --git a/gdb/testsuite/gdb.ada/rdv_wait/foo.adb b/gdb/testsuite/gdb.ada/rdv_wait/foo.adb new file mode 100644 index 00000000000..cc3c22c988f --- /dev/null +++ b/gdb/testsuite/gdb.ada/rdv_wait/foo.adb @@ -0,0 +1,53 @@ +-- Copyright 2012 Free Software Foundation, Inc. +-- +-- This program is free software; you can redistribute it and/or modify +-- it under the terms of the GNU General Public License as published by +-- the Free Software Foundation; either version 3 of the License, or +-- (at your option) any later version. +-- +-- This program is distributed in the hope that it will be useful, +-- but WITHOUT ANY WARRANTY; without even the implied warranty of +-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +-- GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License +-- along with this program. If not, see . + +with Pck; use Pck; + +procedure Foo is + + task type T is + entry Finish; + end T; + type TA is access T; + + task body T is + begin + -- Wait for up to 100 seconds for the Finish Rendez-Vous to occur. + select + accept Finish do + null; + end Finish; + or + delay 100.0; + end select; + end T; + + MIT : TA; + +begin + + -- Create a task, and give it some time to activate and then start + -- its execution. + MIT := new T; + delay 0.01; + + -- Now, call our anchor. The task we just created should now be + -- blocked on a timed entry wait. + Break_Me; + + -- Tell the task to finish before the 100 seconds are up. The test + -- is now finished, no need to wait :). + MIT.Finish; +end Foo; diff --git a/gdb/testsuite/gdb.ada/rdv_wait/pck.adb b/gdb/testsuite/gdb.ada/rdv_wait/pck.adb new file mode 100644 index 00000000000..e5eebdcca5d --- /dev/null +++ b/gdb/testsuite/gdb.ada/rdv_wait/pck.adb @@ -0,0 +1,23 @@ +-- Copyright 2012 Free Software Foundation, Inc. +-- +-- This program is free software; you can redistribute it and/or modify +-- it under the terms of the GNU General Public License as published by +-- the Free Software Foundation; either version 3 of the License, or +-- (at your option) any later version. +-- +-- This program is distributed in the hope that it will be useful, +-- but WITHOUT ANY WARRANTY; without even the implied warranty of +-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +-- GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License +-- along with this program. If not, see . + +package body Pck is + + procedure Break_Me is + begin + null; + end Break_Me; + +end Pck; diff --git a/gdb/testsuite/gdb.ada/rdv_wait/pck.ads b/gdb/testsuite/gdb.ada/rdv_wait/pck.ads new file mode 100644 index 00000000000..afe98f792ed --- /dev/null +++ b/gdb/testsuite/gdb.ada/rdv_wait/pck.ads @@ -0,0 +1,22 @@ +-- Copyright 2012 Free Software Foundation, Inc. +-- +-- This program is free software; you can redistribute it and/or modify +-- it under the terms of the GNU General Public License as published by +-- the Free Software Foundation; either version 3 of the License, or +-- (at your option) any later version. +-- +-- This program is distributed in the hope that it will be useful, +-- but WITHOUT ANY WARRANTY; without even the implied warranty of +-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +-- GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License +-- along with this program. If not, see . + +package Pck is + + procedure Break_Me; + -- A procedure doing nothing, but which is a convenient anchor + -- for inserting breakpoints. + +end Pck; -- 2.30.2