Re: [kbuild-all] drivers/media/dvb-frontends/cxd2841er.c:2393:1: warning: the frame size of 2992 bytes is larger than 2048 bytes
From: Fengguang Wu
Date: Mon Oct 05 2015 - 07:09:40 EST
Hi Abylay,
> cause of this 'Kernel Address sanitizer (KASan)' is enabled in your
> config. With gcc-4.9 kasan was disabled in compile time because of:
> "scripts/Makefile.kasan:23: CONFIG_KASAN: compiler does not support
> all options. Trying minimal configuration"
>
> but with gcc-5 it's enabled.
>
> and
> objdump -d drivers/media/dvb-frontends/cxd2841er.o
>
> shows that KASan adds some instructions to 'cxd2841er_sleep_tc' which
> writes necessary data to -fasan-shadow-offset=0xdffffc0000000000:
> 1476: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
> ...
> 14d3: c7 00 f1 f1 f1 f1 movl $0xf1f1f1f1,(%rax)
> 14d9: c7 40 04 01 f4 f4 f4 movl $0xf4f4f401,0x4(%rax)
> 14e0: c7 40 08 f2 f2 f2 f2 movl $0xf2f2f2f2,0x8(%rax)
> 14e7: c7 40 0c 01 f4 f4 f4 movl $0xf4f4f401,0xc(%rax)
> ...
>
> and function will grow and we get '-Wframe-larger-than=2048' warnings.
>
> So, this warning looks normal (until they less than 8K I think) for
> configurations with KASan enabled.
>
> I can suggest:
> * ignore this warning if KASan enabled
Yes I can easily teach the kbuild robot to ignore this warning when
KASan enabled. Thanks for the explanations!
> * Increase -Wframe-larger-than=2048 to -Wframe-larger-than=8192 if
> KASan enabled ( CONFIG_FRAME_WARN=8192 in kernel .config)
Would it be possible to auto increase the threshold (in below Kconfig) when
KASan is enabled, so that all other developers/testers won't get the warnings,
too?
lib/Kconfig.debug
config FRAME_WARN
int "Warn for stack frames larger than (needs gcc 4.4)"
range 0 8192
default 1024 if !64BIT
default 2048 if 64BIT
Thanks,
Fengguang
> 2015-09-25 12:46 GMT+03:00 Fengguang Wu <fengguang.wu@xxxxxxxxx>:
> > Hi Abylay,
> >
> > This warning can be reproduced with gcc-5.2:
> >
> > =============== commit a6dc60ff1 ===============
> > /home/wfg/linux
> > HEAD is now at a6dc60ff... [media] cxd2841er: Sony CXD2841ER DVB-S/S2/T/T2/C demodulator driver
> > /home/wfg/linux/obj-compiletest
> >
> > make ARCH=x86_64 drivers/media/dvb-frontends/cxd2841er.o
> >
> > grep -a -F drivers/media/dvb-frontends/cxd2841er.c /tmp/build-err-a6dc60ff1209df29ee4668024e93d31f31421932-wfg --color
> > ../drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_sleep_tc':
> > ../drivers/media/dvb-frontends/cxd2841er.c:2393:1: warning: the frame size of 2992 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> > }
> > ^
> > ../drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_set_frontend_tc':
> > ../drivers/media/dvb-frontends/cxd2841er.c:2274:1: warning: the frame size of 4336 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> > }
> > ^
> >
> > =============== PREV commit e025273b86fb4a6440192b809e05332777c3faa5 ===============
> > /home/wfg/linux
> > Previous HEAD position was a6dc60ff... [media] cxd2841er: Sony CXD2841ER DVB-S/S2/T/T2/C demodulator driver
> > HEAD is now at e025273... [media] lnbh25: LNBH25 SEC controller driver
> > /home/wfg/linux/obj-compiletest
> >
> > make ARCH=x86_64 drivers/media/dvb-frontends/cxd2841er.o
> >
> > !!! BUILD ERROR !!!
> > grep -a -F drivers/media/dvb-frontends/cxd2841er.c /tmp/build-err-e025273b86fb4a6440192b809e05332777c3faa5-wfg --color
> >
> > =============== linus/master linus/master ===============
> > /home/wfg/linux
> > Previous HEAD position was e025273... [media] lnbh25: LNBH25 SEC controller driver
> > HEAD is now at 8e64a73... Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
> > /home/wfg/linux/obj-compiletest
> >
> > make ARCH=x86_64 drivers/media/dvb-frontends/cxd2841er.o
> >
> > grep -a -F drivers/media/dvb-frontends/cxd2841er.c /tmp/build-err-8e64a7331702b7888ccf84b2b9ff46ab8e167c7f-wfg --color
> > ../drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_sleep_tc':
> > ../drivers/media/dvb-frontends/cxd2841er.c:2401:1: warning: the frame size of 2984 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> > }
> > ^
> > ../drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_set_frontend_tc':
> > ../drivers/media/dvb-frontends/cxd2841er.c:2282:1: warning: the frame size of 4336 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> > }
> > ^
> >
> > Thanks,
> > Fengguang
> >
> > On Fri, Sep 25, 2015 at 12:21:57PM +0300, Abylay Ospan wrote:
> >> Hello,
> >>
> >> I cannot reproduce this warning. I'm compiling with your config and
> >> following commands:
> >>
> >> git checkout a6dc60ff1209df29ee4668024e93d31f31421932
> >> make ARCH=x86_64
> >>
> >> my gcc version is 4.9.2 (Ubuntu 4.9.2-10ubuntu13)
> >>
> >> warning doesn't appear even if I set:
> >> CONFIG_FRAME_WARN=128
> >>
> >> Please point me if problem still exist.
> >>
> >> thanks !
> >>
> >>
> >>
> >> 2015-09-17 9:05 GMT+03:00 kbuild test robot <fengguang.wu@xxxxxxxxx>:
> >> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> >> > head: 72714841b705a5b9bccf37ee85a62352bee3a3ef
> >> > commit: a6dc60ff1209df29ee4668024e93d31f31421932 [media] cxd2841er: Sony CXD2841ER DVB-S/S2/T/T2/C demodulator driver
> >> > date: 5 weeks ago
> >> > config: x86_64-randconfig-b0-09171322 (attached as .config)
> >> > reproduce:
> >> > git checkout a6dc60ff1209df29ee4668024e93d31f31421932
> >> > # save the attached .config to linux build tree
> >> > make ARCH=x86_64
> >> >
> >> > All warnings (new ones prefixed by >>):
> >> >
> >> > drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_sleep_tc':
> >> >>> drivers/media/dvb-frontends/cxd2841er.c:2393:1: warning: the frame size of 2992 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> >> > }
> >> > ^
> >> > drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_set_frontend_tc':
> >> > drivers/media/dvb-frontends/cxd2841er.c:2274:1: warning: the frame size of 4336 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> >> > }
> >> > ^
> >> >
> >> > vim +2393 drivers/media/dvb-frontends/cxd2841er.c
> >> >
> >> > 2377 case SYS_DVBC_ANNEX_A:
> >> > 2378 cxd2841er_active_c_to_sleep_tc(priv);
> >> > 2379 break;
> >> > 2380 default:
> >> > 2381 dev_warn(&priv->i2c->dev,
> >> > 2382 "%s(): unknown delivery system %d\n",
> >> > 2383 __func__, priv->system);
> >> > 2384 }
> >> > 2385 }
> >> > 2386 if (priv->state != STATE_SLEEP_TC) {
> >> > 2387 dev_err(&priv->i2c->dev, "%s(): invalid state %d\n",
> >> > 2388 __func__, priv->state);
> >> > 2389 return -EINVAL;
> >> > 2390 }
> >> > 2391 cxd2841er_sleep_tc_to_shutdown(priv);
> >> > 2392 return 0;
> >> >> 2393 }
> >> > 2394
> >> > 2395 static int cxd2841er_send_burst(struct dvb_frontend *fe,
> >> > 2396 enum fe_sec_mini_cmd burst)
> >> > 2397 {
> >> > 2398 u8 data;
> >> > 2399 struct cxd2841er_priv *priv = fe->demodulator_priv;
> >> > 2400
> >> > 2401 dev_dbg(&priv->i2c->dev, "%s(): burst mode %s\n", __func__,
> >> >
> >> > ---
> >> > 0-DAY kernel test infrastructure Open Source Technology Center
> >> > https://lists.01.org/pipermail/kbuild-all Intel Corporation
> >>
> >>
> >>
> >> --
> >> Abylay Ospan,
> >> NetUP Inc.
> >> http://www.netup.tv
> >> _______________________________________________
> >> kbuild-all mailing list
> >> kbuild-all@xxxxxxxxxxxx
> >> https://lists.01.org/mailman/listinfo/kbuild-all
>
>
>
> --
> Abylay Ospan,
> NetUP Inc.
> http://www.netup.tv
> _______________________________________________
> kbuild-all mailing list
> kbuild-all@xxxxxxxxxxxx
> https://lists.01.org/mailman/listinfo/kbuild-all
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