# 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 # 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 # Fixes: 8cd54c1c8480 ("iov_iter: separate direction from flavour") # Cc: Matthew Wilcox # Cc: Al Viro # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux-gcc --version # < /opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux-ld --version # < git log --format=%s --max-count=1 a180bd1d7e16173d965b263c5a536aa40afa2a2a # < make -s -j 24 ARCH=sparc O=/kisskb/build/linus_sparc-allmodconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux- allmodconfig # Added to kconfig CONFIG_64BIT=n # Added to kconfig CONFIG_BUILD_DOCSRC=n # Added to kconfig CONFIG_HAVE_FTRACE_MCOUNT_RECORD=n # Added to kconfig CONFIG_SAMPLES=n # Added to kconfig CONFIG_MODULE_SIG=n # < make -s -j 24 ARCH=sparc O=/kisskb/build/linus_sparc-allmodconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux- help # make -s -j 24 ARCH=sparc O=/kisskb/build/linus_sparc-allmodconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux- olddefconfig # make -s -j 24 ARCH=sparc O=/kisskb/build/linus_sparc-allmodconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux- :1511:2: warning: #warning syscall clone3 not implemented [-Wcpp] /kisskb/src/drivers/tty/serial/sunzilog.c:1128:13: warning: 'sunzilog_putchar' defined but not used [-Wunused-function] static void sunzilog_putchar(struct uart_port *port, int ch) ^ /kisskb/src/drivers/input/joystick/analog.c:160:2: warning: #warning Precise timer not defined for this architecture. [-Wcpp] #warning Precise timer not defined for this architecture. ^ /kisskb/src/drivers/scsi/ufs/ufshcd.c:9016:12: warning: 'ufshcd_wl_runtime_suspend' defined but not used [-Wunused-function] static int ufshcd_wl_runtime_suspend(struct device *dev) ^ /kisskb/src/drivers/scsi/ufs/ufshcd.c:9036:12: warning: 'ufshcd_wl_runtime_resume' defined but not used [-Wunused-function] static int ufshcd_wl_runtime_resume(struct device *dev) ^ /kisskb/src/drivers/scsi/ufs/ufshcd.c:9769:12: warning: 'ufshcd_rpmb_resume' defined but not used [-Wunused-function] static int ufshcd_rpmb_resume(struct device *dev) ^ In file included from :0:0: /kisskb/src/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c: In function 'ifh_encode_bitfield': /kisskb/src/include/linux/compiler_types.h:328:38: error: call to '__compiletime_assert_399' declared with attribute error: Unsupported width, must be <= 40 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ /kisskb/src/include/linux/compiler_types.h:309:4: note: in definition of macro '__compiletime_assert' prefix ## suffix(); \ ^ /kisskb/src/include/linux/compiler_types.h:328:2: note: in expansion of macro '_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ /kisskb/src/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c:28:2: note: in expansion of macro 'compiletime_assert' compiletime_assert(width <= 40, "Unsupported width, must be <= 40"); ^ make[6]: *** [/kisskb/src/scripts/Makefile.build:273: drivers/net/ethernet/microchip/sparx5/sparx5_netdev.o] Error 1 make[5]: *** [/kisskb/src/scripts/Makefile.build:516: drivers/net/ethernet/microchip/sparx5] Error 2 make[4]: *** [/kisskb/src/scripts/Makefile.build:516: drivers/net/ethernet/microchip] Error 2 make[4]: *** Waiting for unfinished jobs.... make[3]: *** [/kisskb/src/scripts/Makefile.build:516: drivers/net/ethernet] Error 2 make[3]: *** Waiting for unfinished jobs.... make[2]: *** [/kisskb/src/scripts/Makefile.build:516: drivers/net] Error 2 make[1]: *** [/kisskb/src/Makefile:1847: drivers] Error 2 make: *** [Makefile:215: __sub-make] Error 2 Command 'make -s -j 24 ARCH=sparc O=/kisskb/build/linus_sparc-allmodconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux- ' returned non-zero exit status 2 # rm -rf /kisskb/build/linus_sparc-allmodconfig_sparc64 # Build took: 0:15:29.807032