Re: [PATCH] gdb/testsuite: make gdb.dwarf2/dw2-empty-inline-ranges.exp work when ASLR can't be disabled

[Andrew Burgess <aburgess@redhat.com>]

Simon Marchi <simon.marchi@efficios.com> writes:

> A colleague that goes by the name "Luis Machado" reported a failure when
> running gdb.dwarf2/dw2-empty-inline-ranges.exp.  After investigation, we
> found that the conditions for the test to fail are:
>
>  - running in an environment where GDB can't disable address space
>    randomization (such as in a container where that capability is
>    removed)
>
>  - a toolchain generating position-independent executables
>
> The test does a first run to grab the addresses of a few labels defined
> in the source file.  It then crafts the DWARF using these addresses.
> And then it does a second run for the actual test stuff.
>
> When the executable is PIE and ASLR is active, then the addresses in
> both runs don't agree, which the test doesn't expect.
>
> It is possible to emulate the failure by inserting some:
>
>     gdb_test_no_output "set disable-randomization off"
>
> after both "prepare_for_testing" calls.  The (first) failure then
> manifests as:
>
>     FAIL: gdb.dwarf2/dw2-empty-inline-ranges.exp: dwarf_version=4: empty_loc=start: entry_pc_type=empty: stopped at entry-pc
>
> This test compares the expected stop PC "entry_pc" with the actual stop
> PC "pc".  In my example run, they were indeed different:
>
>     pc       = 0x5603ec67a159
>     entry_pc = 0x55baba6a9159
>
> The simplest way to fix this, which this patch implements, is to use
> "nopie" when building the binaries.  I don't think this affects the
> effectiveness of the test.
>
> Also, in the first run, it is longer necessary to run the inferior
> before grabbing the addresses, they are going to be the same with a
> non-PIE executable.  So remove that.

Thanks for fixing this.  LGTM.

Approved-By: Andrew Burgess <aburgess@redhat.com>


Thanks,
Andrew