[PATCH v5 00/14] Fix BZ 25631 - core file memory access problem

[Kevin Buettner]

On Thu, 23 Jul 2020 07:37:42 -0300
Luis Machado <luis.machado@linaro.org> wrote:

> On 7/23/20 12:49 AM, Kevin Buettner wrote:
> > On Wed, 22 Jul 2020 19:40:18 -0300
> > Luis Machado <luis.machado@linaro.org> wrote:
> >   
> >> I'm seeing the following regressions on AArch64 Linux running Ubuntu
> >> 18.04 (GCC 7).
> >>
> >> FAIL: gdb.base/corefile.exp: backtrace in corefile.exp
> >> FAIL: gdb.base/corefile.exp: core-file warning-free
> >> FAIL: gdb.base/corefile.exp: print func2::coremaker_local
> >> FAIL: gdb.base/corefile.exp: up in corefile.exp
> >> FAIL: gdb.base/corefile.exp: up in corefile.exp (reinit)
> >>
> >> On a quick look, the test doesn't go according to what is expected.
> >>
> >> --
> >>
> >> (gdb) PASS: gdb.base/corefile.exp: print coremaker_ro
> >> print func2::coremaker_local^M
> >> No frame is currently executing in block func2.^M
> >> (gdb) FAIL: gdb.base/corefile.exp: print func2::coremaker_local
> >> ...
> >> (gdb) PASS: gdb.base/corefile.exp: $_exitcode is void
> >> bt^M
> >> #0  0x0000ffff80d1c4d8 in raise () from /lib/aarch64-linux-gnu/libc.so.6^M
> >> Backtrace stopped: previous frame identical to this frame (corrupt stack?)^M
> >> (gdb) FAIL: gdb.base/corefile.exp: backtrace in corefile.exp
> >> up^M
> >> Initial frame selected; you cannot go up.^M
> >> (gdb) FAIL: gdb.base/corefile.exp: up in corefile.exp
> >> ...
> >> (gdb) file gdb/testsuite/outputs/gdb.base/corefile/corefile^M
> >> Load new symbol table from
> >> "gdb/testsuite/outputs/gdb.base/corefile/corefile"? (y or n) y^M
> >> Reading symbols from gdb/testsuite/outputs/gdb.base/corefile/corefile...^M
> >> (gdb) up^M
> >> Initial frame selected; you cannot go up.^M
> >> (gdb) FAIL: gdb.base/corefile.exp: up in corefile.exp (reinit)  
> > 
> > Hi Luis,
> > 
> > I'm not seeing these failures on my Raspberry Pi 4 running aarch64
> > rawhide.  I have a spare Pi upon which I'll install Ubuntu 18.04.4.
> > 
> > In the interim, would it be possible for you to show me the same
> > sections of the log file from a test run using a GDB build prior to my
> > core file patches?  
> 
> I've attached the complete log files for both runs. Hopefully that will 
> be more useful.
> 
> Please let me know if you need anything else and I can fetch it.

Thanks for sending the log files.  One of the things I found puzzling
were these messages in after.log:

(gdb) core-file /home/user/work/build/binutils-gdb-master/gdb/testsuite/outputs/gdb.base/corefile/corefile.core
warning: Can't open file (null) during file-backed mapping note processing
warning: Can't open file (null) during file-backed mapping note processing
warning: Can't open file (null) during file-backed mapping note processing
warning: Can't open file (null) during file-backed mapping note processing
warning: Can't open file (null) during file-backed mapping note processing
warning: Can't open file (null) during file-backed mapping note processing
warning: Can't open file (null) during file-backed mapping note processing

Something is going terribly wrong!

I've installed Ubuntu 18.04.4 on a Raspberry Pi 3 B+.

So far, I haven't been able to reproduce the failures that you're seeing.

kev@ubuntu:/ironwood1/sourceware-git/u18.04-rpi3-master/bld/gdb$ cat /etc/issue
Ubuntu 18.04.4 LTS \n \l

kev@ubuntu:/ironwood1/sourceware-git/u18.04-rpi3-master/bld/gdb$ uname -a
Linux ubuntu 5.3.0-1028-raspi2 #30~18.04.2-Ubuntu SMP Fri Jun 19
05:12:46 UTC 2020 aarch64 aarch64 aarch64 GNU/Linux

kev@ubuntu:/ironwood1/sourceware-git/u18.04-rpi3-master/bld/gdb$ make
check TESTS="gdb.base/corefile.exp"
...
		=== gdb Summary ===

# of expected passes		30

I'd like to see the following...

1) The output of "uname -a".

2) The output of "cat /etc/issue".

3) The output of "cat /proc/self/coredump_filter".  (Is there a better
way to know what the global filter is?)

4) The before / after contents of testsuite/outputs/gdb.base/corefile .

Thanks,

Kevin