Buildresult: linus/um-allmodconfig/um-x86_64 built on Dec 18 2020, 05:43

kisskb

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Status:	Failed
Date/Time:	Dec 18 2020, 05:43
Duration:	0:04:56.011420
Builder:	ka2
Revision:	drm/edid: fix objtool warning in drm_cvt_modes() (`d652d5f1eeeb06046009f4fcb9b4542249526916)`
Target:	linus/um-allmodconfig/um-x86_64
Branch:	linus
Compiler:	um-x86_64 (x86_64-linux-gcc.br_real (Buildroot 2017.05) 5.4.0 / GNU ld (GNU Binutils) 2.27)
Config:	allmodconfig (download)
Log:	Download original Possible errors make[5]: * [Makefile:287: elfdep] Error 1 make[4]: * [kernel/bpf/preload/Makefile:8: kernel/bpf/preload/libbpf.a] Error 2 make[3]: * [scripts/Makefile.build:496: kernel/bpf/preload] Error 2 make[2]: * [scripts/Makefile.build:496: kernel/bpf] Error 2 make[1]: * [Makefile:1805: kernel] Error 2 make: * [Makefile:185: __sub-make] Error 2 Possible warnings (8) .config:4372:warning: override: reassigning to symbol GCC_PLUGIN_CYC_COMPLEXITY .config:4374:warning: override: reassigning to symbol GCC_PLUGIN_LATENT_ENTROPY .config:4378:warning: override: reassigning to symbol UML_NET_ETHERTAP .config:4380:warning: override: reassigning to symbol UML_NET_SLIP .config:4383:warning: override: reassigning to symbol UML_NET_MCAST .config:4385:warning: override: reassigning to symbol UML_NET_SLIRP arch/um/os-Linux/signal.c:51:1: warning: the frame size of 2976 bytes is larger than 2048 bytes [-Wframe-larger-than=] arch/um/os-Linux/signal.c:95:1: warning: the frame size of 2960 bytes is larger than 2048 bytes [-Wframe-larger-than=] Full Log # git rev-parse -q --verify d652d5f1eeeb06046009f4fcb9b4542249526916^{commit} d652d5f1eeeb06046009f4fcb9b4542249526916 already have revision, skipping fetch # git checkout -q -f -B kisskb d652d5f1eeeb06046009f4fcb9b4542249526916 # git clean -qxdf # < git log -1 # commit d652d5f1eeeb06046009f4fcb9b4542249526916 # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Thu Dec 17 09:27:57 2020 -0800 # # drm/edid: fix objtool warning in drm_cvt_modes() # # Commit 991fcb77f490 ("drm/edid: Fix uninitialized variable in # drm_cvt_modes()") just replaced one warning with another. # # The original warning about a possibly uninitialized variable was due to # the compiler not being smart enough to see that the case statement # actually enumerated all possible cases. And the initial fix was just to # add a "default" case that had a single "unreachable()", just to tell the # compiler that that situation cannot happen. # # However, that doesn't actually fix the fundamental reason for the # problem: the compiler still doesn't see that the existing case # statements enumerate all possibilities, so the compiler will still # generate code to jump to that unreachable case statement. It just won't # complain about an uninitialized variable any more. # # So now the compiler generates code to our inline asm marker that we told # it would not fall through, and end end result is basically random. We # have created a bridge to nowhere. # # And then, depending on the random details of just exactly what the # compiler ends up doing, 'objtool' might end up complaining about the # conditional branches (for conditions that cannot happen, and that thus # will never be taken - but if the compiler was not smart enough to figure # that out, we can't expect objtool to do so) going off in the weeds. # # So depending on how the compiler has laid out the result, you might see # something like this: # # drivers/gpu/drm/drm_edid.o: warning: objtool: do_cvt_mode() falls through to next function drm_mode_detailed.isra.0() # # and now you have a truly inscrutable warning that makes no sense at all # unless you start looking at whatever random code the compiler happened # to generate for our bare "unreachable()" statement. # # IOW, don't use "unreachable()" unless you have an _active_ operation # that generates code that actually makes it obvious that something is not # reachable (ie an UD instruction or similar). # # Solve the "compiler isn't smart enough" problem by just marking one of # the cases as "default", so that even when the compiler doesn't otherwise # see that we've enumerated all cases, the compiler will feel happy and # safe about there always being a valid case that initializes the 'width' # variable. # # This also generates better code, since now the compiler doesn't generate # comparisons for five different possibilities (the four real ones and the # one that can't happen), but just for the three real ones and "the rest" # (which is that last one). # # A smart enough compiler that sees that we cover all the cases won't care. # # Cc: Lyude Paul <lyude@redhat.com> # Cc: Ilia Mirkin <imirkin@alum.mit.edu> # Cc: Josh Poimboeuf <jpoimboe@redhat.com> # Cc: Peter Zijlstra <peterz@infradead.org> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-gcc --version # < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-ld --version # < git log --format=%s --max-count=1 d652d5f1eeeb06046009f4fcb9b4542249526916 # < make -s -j 48 ARCH=um O=/kisskb/build/linus_um-allmodconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 allmodconfig # Added to kconfig CONFIG_STANDALONE=y # Added to kconfig CONFIG_KCOV=n # Added to kconfig CONFIG_GCC_PLUGINS=n # Added to kconfig CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=n # Added to kconfig CONFIG_GCC_PLUGIN_SANCOV=n # Added to kconfig CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n # Added to kconfig CONFIG_GCC_PLUGIN_STRUCTLEAK=n # Added to kconfig CONFIG_GCC_PLUGIN_RANDSTRUCT=n # Added to kconfig CONFIG_UML_NET=n # Added to kconfig CONFIG_UML_NET_ETHERTAP=n # Added to kconfig CONFIG_UML_NET_TUNTAP=n # Added to kconfig CONFIG_UML_NET_SLIP=n # Added to kconfig CONFIG_UML_NET_DAEMON=n # Added to kconfig CONFIG_UML_NET_VDE=n # Added to kconfig CONFIG_UML_NET_MCAST=n # Added to kconfig CONFIG_UML_NET_PCAP=n # Added to kconfig CONFIG_UML_NET_SLIRP=n # Added to kconfig CONFIG_GCOV_KERNEL=n # Added to kconfig CONFIG_DEBUG_INFO_BTF=n # < make -s -j 48 ARCH=um O=/kisskb/build/linus_um-allmodconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 help # make -s -j 48 ARCH=um O=/kisskb/build/linus_um-allmodconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 olddefconfig .config:4372:warning: override: reassigning to symbol GCC_PLUGIN_CYC_COMPLEXITY .config:4374:warning: override: reassigning to symbol GCC_PLUGIN_LATENT_ENTROPY .config:4378:warning: override: reassigning to symbol UML_NET_ETHERTAP .config:4380:warning: override: reassigning to symbol UML_NET_SLIP .config:4383:warning: override: reassigning to symbol UML_NET_MCAST .config:4385:warning: override: reassigning to symbol UML_NET_SLIRP # make -s -j 48 ARCH=um O=/kisskb/build/linus_um-allmodconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 /kisskb/src/arch/um/os-Linux/signal.c: In function 'sig_handler_common': /kisskb/src/arch/um/os-Linux/signal.c:51:1: warning: the frame size of 2976 bytes is larger than 2048 bytes [-Wframe-larger-than=] } ^ /kisskb/src/arch/um/os-Linux/signal.c: In function 'timer_real_alarm_handler': /kisskb/src/arch/um/os-Linux/signal.c:95:1: warning: the frame size of 2960 bytes is larger than 2048 bytes [-Wframe-larger-than=] } ^ Auto-detecting system features: ... libelf: [ [31mOFF[m ] ... zlib: [ [31mOFF[m ] ... bpf: [ [32mon[m ] No libelf found make[5]: * [Makefile:287: elfdep] Error 1 make[4]: * [/kisskb/src/kernel/bpf/preload/Makefile:8: kernel/bpf/preload/libbpf.a] Error 2 make[3]: * [/kisskb/src/scripts/Makefile.build:496: kernel/bpf/preload] Error 2 make[2]: * [/kisskb/src/scripts/Makefile.build:496: kernel/bpf] Error 2 make[2]: * Waiting for unfinished jobs.... make[1]: * [/kisskb/src/Makefile:1805: kernel] Error 2 make[1]: * Waiting for unfinished jobs.... make: * [Makefile:185: __sub-make] Error 2 Command 'make -s -j 48 ARCH=um O=/kisskb/build/linus_um-allmodconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 ' returned non-zero exit status 2 # rm -rf /kisskb/build/linus_um-allmodconfig_um-x86_64 # Build took: 0:04:56.011420

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