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    Kbuild: always define endianess in kconfig.h · 101110f6
    Arnd Bergmann 提交于
    Build testing with LTO found a couple of files that get compiled
    differently depending on whether asm/byteorder.h gets included early
    enough or not.  In particular, include/asm-generic/qrwlock_types.h is
    affected by this, but there are probably others as well.
    
    The symptom is a series of LTO link time warnings, including these:
    
        net/netlabel/netlabel_unlabeled.h:223: error: type of 'netlbl_unlhsh_add' does not match original declaration [-Werror=lto-type-mismatch]
         int netlbl_unlhsh_add(struct net *net,
        net/netlabel/netlabel_unlabeled.c:377: note: 'netlbl_unlhsh_add' was previously declared here
    
        include/net/ipv6.h:360: error: type of 'ipv6_renew_options_kern' does not match original declaration [-Werror=lto-type-mismatch]
         ipv6_renew_options_kern(struct sock *sk,
        net/ipv6/exthdrs.c:1162: note: 'ipv6_renew_options_kern' was previously declared here
    
        net/core/dev.c:761: note: 'dev_get_by_name_rcu' was previously declared here
         struct net_device *dev_get_by_name_rcu(struct net *net, const char *name)
        net/core/dev.c:761: note: code may be misoptimized unless -fno-strict-aliasing is used
    
        drivers/gpu/drm/i915/i915_drv.h:3377: error: type of 'i915_gem_object_set_to_wc_domain' does not match original declaration [-Werror=lto-type-mismatch]
         i915_gem_object_set_to_wc_domain(struct drm_i915_gem_object *obj, bool write);
        drivers/gpu/drm/i915/i915_gem.c:3639: note: 'i915_gem_object_set_to_wc_domain' was previously declared here
    
        include/linux/debugfs.h:92:9: error: type of 'debugfs_attr_read' does not match original declaration [-Werror=lto-type-mismatch]
         ssize_t debugfs_attr_read(struct file *file, char __user *buf,
        fs/debugfs/file.c:318: note: 'debugfs_attr_read' was previously declared here
    
        include/linux/rwlock_api_smp.h:30: error: type of '_raw_read_unlock' does not match original declaration [-Werror=lto-type-mismatch]
         void __lockfunc _raw_read_unlock(rwlock_t *lock) __releases(lock);
        kernel/locking/spinlock.c:246:26: note: '_raw_read_unlock' was previously declared here
    
        include/linux/fs.h:3308:5: error: type of 'simple_attr_open' does not match original declaration [-Werror=lto-type-mismatch]
         int simple_attr_open(struct inode *inode, struct file *file,
        fs/libfs.c:795: note: 'simple_attr_open' was previously declared here
    
    All of the above are caused by include/asm-generic/qrwlock_types.h
    failing to include asm/byteorder.h after commit e0d02285
    ("locking/qrwlock: Use 'struct qrwlock' instead of 'struct __qrwlock'")
    in linux-4.15.
    
    Similar bugs may or may not exist in older kernels as well, but there is
    no easy way to test those with link-time optimizations, and kernels
    before 4.14 are harder to fix because they don't have Babu's patch
    series
    
    We had similar issues with CONFIG_ symbols in the past and ended up
    always including the configuration headers though linux/kconfig.h.  This
    works around the issue through that same file, defining either
    __BIG_ENDIAN or __LITTLE_ENDIAN depending on CONFIG_CPU_BIG_ENDIAN,
    which is now always set on all architectures since commit 4c97a0c8
    ("arch: define CPU_BIG_ENDIAN for all fixed big endian archs").
    
    Link: http://lkml.kernel.org/r/20180202154104.1522809-2-arnd@arndb.deSigned-off-by: NArnd Bergmann <arnd@arndb.de>
    Cc: Babu Moger <babu.moger@amd.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
    Cc: Nicolas Pitre <nico@linaro.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    101110f6
kconfig.h 2.4 KB