[libvirt] [PATCH v2 5/5] Prevent more compiler optimization of mockable functions

[Marc-André Lureau]

On Wed, Jul 12, 2017 at 1:54 AM Marc-André Lureau <
marcandre.lureau at gmail.com> wrote:

> Hi
>
> On Mon, Jul 10, 2017 at 1:14 PM Peter Krempa <pkrempa at redhat.com> wrote:
>
>> On Wed, Jul 05, 2017 at 12:58:51 +0100, Daniel Berrange wrote:
>> > Currently all mockable functions are annotated with the 'noinline'
>> > attribute. This is insufficient to guarantee that a function can
>> > be reliably mocked with an LD_PRELOAD. The C language spec allows
>> > the compiler to assume there is only a single implementation of
>> > each function. It can thus do things like propagating constant
>> > return values into the caller at compile time, or creating
>> > multiple specialized copies of the function body each optimized
>> > for a different caller. To prevent these optimizations we must
>> > also set the 'noclone' and 'weak' attributes.
>> >
>> > This fixes the test suite when libvirt.so is built with CLang
>> > with optimization enabled.
>> >
>> > Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
>>
>
> This patch makes virtlogd crash:
>
>  (gdb) bt
> #0  0x0000000000000000 in ?? ()
> #1  0x00005555555a8084 in virHashCreateFull (size=size at entry=5,
> dataFree=0x5555555b0930 <virObjectFreeHashData>, keyCode=keyCode at entry=0x5555555a7c30
> <virHashStrCode>, keyEqual=keyEqual at entry=0x5555555a7c10
> <virHashStrEqual>, keyCopy=keyCopy at entry=0x5555555a7bb0 <virHashStrCopy>,
> keyFree=keyFree at entry=0x5555555a7b90 <virHashStrFree>) at
> util/virhash.c:167
> #2  0x00005555555a8151 in virHashCreate (size=size at entry=5,
> dataFree=<optimized out>) at util/virhash.c:196
> #3  0x00005555555779f0 in virNetDaemonNew () at rpc/virnetdaemon.c:137
> #4  0x00005555555708ec in virLogDaemonNew (privileged=false,
> config=0x555555820940) at logging/log_daemon.c:163
> #5  main (argc=<optimized out>, argv=0x7fffffffd888) at
> logging/log_daemon.c:1069
>
> any idea?
>
>
(btw, this is on f25,  gcc (GCC) 6.3.1 20161221 (Red Hat 6.3.1-1))

> ---
>> >  build-aux/mock-noinline.pl      |  2 +-
>> >  src/check-symfile.pl            |  2 +-
>> >  src/internal.h                  | 23 ++++++++++++++++++-----
>> >  src/qemu/qemu_capspriv.h        |  2 +-
>> >  src/rpc/virnetsocket.h          |  4 ++--
>> >  src/util/vircommand.h           |  2 +-
>> >  src/util/vircrypto.h            |  2 +-
>> >  src/util/virfile.h              |  2 +-
>> >  src/util/virhostcpu.h           |  4 ++--
>> >  src/util/virmacaddr.h           |  2 +-
>> >  src/util/virnetdev.h            |  8 ++++----
>> >  src/util/virnetdevip.h          |  2 +-
>> >  src/util/virnetdevopenvswitch.h |  2 +-
>> >  src/util/virnetdevtap.h         |  6 +++---
>> >  src/util/virnuma.h              | 16 ++++++++--------
>> >  src/util/virrandom.h            |  6 +++---
>> >  src/util/virscsi.h              |  2 +-
>> >  src/util/virscsivhost.h         |  2 +-
>> >  src/util/virtpm.h               |  2 +-
>> >  src/util/virutil.h              | 10 +++++-----
>> >  src/util/viruuid.h              |  2 +-
>> >  21 files changed, 58 insertions(+), 45 deletions(-)
>>
>> ACK
>> --
>> libvir-list mailing list
>> libvir-list at redhat.com
>> https://www.redhat.com/mailman/listinfo/libvir-list
>
> --
> Marc-André Lureau
>
-- 
Marc-André Lureau
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