2015-10-05 14:09 GMT+03:00 Fengguang Wu <fengguang.wu@xxxxxxxxx>: > 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? > Makes sense, although 8K is too much, I think. 6K probably enough. > 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
