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0c92d8c1c3
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.
33 lines
1.1 KiB
Plaintext
33 lines
1.1 KiB
Plaintext
# Copyright 2012 Free Software Foundation, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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load_lib "ada.exp"
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standard_ada_testfile foo
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if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } {
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return -1
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}
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clean_restart ${testfile}
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runto "break_me"
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# Switch to task 2, and verify that GDB is able to unwind all the way
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# to foo.T.
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gdb_test "task 2" \
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[join {"\\\[Switching to task 2\\\].*" \
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".*foo\\.t \\(.*\\).*foo\\.adb:.*"} ""]
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