From dcd27ddf875d6b913f1ddb0573c22b0931e36061 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Sat, 22 Jul 2017 00:01:03 +0200 Subject: [PATCH] gdb.python/py-unwind: Disable stack protection [I made some typo fixes but forgot to amend my commit before sending the patch, hence this v2.] I see the following failure on Ubuntu 16.04's gcc 5.4.0: Running /home/emaisin/src/binutils-gdb/gdb/testsuite/gdb.python/py-unwind.exp ... FAIL: gdb.python/py-unwind.exp: continue to breakpoint: break backtrace-broken FAIL: gdb.python/py-unwind.exp: Backtrace restored by unwinder (pattern 1) The problem is that the test expects a very particular stack layout. When stack protection is enabled, it adds a canary value which looks like an additional local variable. This makes the test complain about a bad stack layout and fail. The simple solution is to disable stack protection for that test using -fno-stack-protector. I checked older compilers (gcc 4.4, clang 3.5) and they support that flag, so I don't think it's necessary to probe for whether the compiler supports it. Maybe a better solution would be to change the test to make it cope with different stack layouts (perhaps it could save addresses of stuff in some global variables which GDB/the unwinder would read). I'll go with the simple solution for now though. gdb/testsuite/ChangeLog: * gdb.python/py-unwind.exp: Disable stack protection when building test file. --- gdb/testsuite/ChangeLog | 5 +++++ gdb/testsuite/gdb.python/py-unwind.exp | 7 ++++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index eef141d14e2..273d1f78865 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2017-07-22 Simon Marchi + + * gdb.python/py-unwind.exp: Disable stack protection when + building test file. + 2017-07-20 Pedro Alves * gdb.base/default.exp (set language): Adjust expected output. diff --git a/gdb/testsuite/gdb.python/py-unwind.exp b/gdb/testsuite/gdb.python/py-unwind.exp index 625b04c40e3..86e695cb924 100644 --- a/gdb/testsuite/gdb.python/py-unwind.exp +++ b/gdb/testsuite/gdb.python/py-unwind.exp @@ -20,7 +20,12 @@ load_lib gdb-python.exp standard_testfile -if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } { +# Stack protection can make the stack look a bit different, breaking the +# assumptions this test has about its layout. + +set flags "additional_flags=-fno-stack-protector" + +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} "debug $flags"] } { return -1 }