Buildresult: linus/um-allmodconfig/um-x86_64 built on Jul 16 2021, 14:12

kisskb

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Status:	OK
Date/Time:	Jul 16 2021, 14:12
Duration:	0:11:00.763960
Builder:	ka4
Revision:	iov_iter: remove uaccess_kernel() warning from iov_iter_init() (`a180bd1d7e16173d965b263c5a536aa40afa2a2a)`
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 warnings (7) .config:4565:warning: override: reassigning to symbol GCC_PLUGIN_CYC_COMPLEXITY .config:4567:warning: override: reassigning to symbol GCC_PLUGIN_LATENT_ENTROPY .config:4571:warning: override: reassigning to symbol UML_NET_ETHERTAP .config:4573:warning: override: reassigning to symbol UML_NET_SLIP .config:4576:warning: override: reassigning to symbol UML_NET_MCAST .config:4578:warning: override: reassigning to symbol UML_NET_SLIRP kernel/trace/trace_osnoise.c:1461:8: warning: 'main' is usually a function [-Wmain] Full Log # git rev-parse -q --verify a180bd1d7e16173d965b263c5a536aa40afa2a2a^{commit} a180bd1d7e16173d965b263c5a536aa40afa2a2a already have revision, skipping fetch # git checkout -q -f -B kisskb a180bd1d7e16173d965b263c5a536aa40afa2a2a # git clean -qxdf # < git log -1 # commit a180bd1d7e16173d965b263c5a536aa40afa2a2a # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Sun Jul 4 16:12:42 2021 -0700 # # iov_iter: remove uaccess_kernel() warning from iov_iter_init() # # This warning was there to catch any architectures that still use # CONFIG_SET_FS, and that would mis-use iov_iter_init() for anything that # wasn't a proper user space pointer. So that # # WARN_ON_ONCE(uaccess_kernel()); # # makes perfect conceptual sense: you really shouldn't use a kernel # pointer with set_fs(KERNEL_DS) and then pass it to iov_iter_init(). # # HOWEVER. # # Guenter Roeck reports that this warning actually triggers in no-mmu # configurations of both ARM and m68k. And the reason isn't that they # pass in a kernel pointer under set_fs(KERNEL_DS) at all: the reason is # that in those configurations, "uaccess_kernel()" is simply not reliable. # # Those no-mmu setups set USER_DS and KERNEL_DS to the same values, so you # can't test for the difference. # # In particular, the no-mmu case for ARM does # # #define USER_DS KERNEL_DS # #define uaccess_kernel() (true) # # so USER_DS and KERNEL_DS have the same value, and uaccess_kernel() is # always trivially true. # # The m68k case is slightly different and not quite as obvious. It does # (spread out over multiple header files just to be extra exciting: # asm/processor.h, asm/segment.h and asm-generic/uaccess.h): # # #define TASK_SIZE (0xFFFFFFFFUL) # #define USER_DS MAKE_MM_SEG(TASK_SIZE) # #define KERNEL_DS MAKE_MM_SEG(~0UL) # #define get_fs() (current_thread_info()->addr_limit) # #define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg) # # but the end result is the same: uaccess_kernel() will always be true, # because USER_DS and KERNEL_DS end up having the same value, even if that # value is defined differently. # # This is very arguably a misfeature in those implementations, but in the # end we don't really care. All modern architectures have gotten rid of # set_fs() already, and generic kernel code never uses it. And while the # sanity check was a nice idea, an architecture would have to go the extra # mile to actually break this. # # So this well-intentioned warning isn't really all that likely to find # anything but these known false positives, and as such just isn't worth # maintaining. # # Reported-by: Guenter Roeck <linux@roeck-us.net> # Fixes: 8cd54c1c8480 ("iov_iter: separate direction from flavour") # Cc: Matthew Wilcox <willy@infradead.org> # Cc: Al Viro <viro@zeniv.linux.org.uk> # 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 a180bd1d7e16173d965b263c5a536aa40afa2a2a # < make -s -j 10 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 # Added to kconfig CONFIG_BPF_PRELOAD=n # < make -s -j 10 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 10 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:4565:warning: override: reassigning to symbol GCC_PLUGIN_CYC_COMPLEXITY .config:4567:warning: override: reassigning to symbol GCC_PLUGIN_LATENT_ENTROPY .config:4571:warning: override: reassigning to symbol UML_NET_ETHERTAP .config:4573:warning: override: reassigning to symbol UML_NET_SLIP .config:4576:warning: override: reassigning to symbol UML_NET_MCAST .config:4578:warning: override: reassigning to symbol UML_NET_SLIRP # make -s -j 10 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/kernel/trace/trace_osnoise.c: In function 'start_kthread': /kisskb/src/kernel/trace/trace_osnoise.c:1461:8: warning: 'main' is usually a function [-Wmain] void *main = osnoise_main; ^ LINK linux Completed OK # rm -rf /kisskb/build/linus_um-allmodconfig_um-x86_64 # Build took: 0:11:00.763960

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