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https://github.com/brain-hackers/linux-brain.git
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f2ae679411
Alpha provides a custom implementation of dec_and_lock(). The functions is split into two parts: - atomic_add_unless() + return 0 (fast path in assembly) - remaining part including locking (slow path in C) Comparing the result of the alpha implementation with the generic implementation compiled by gcc it looks like the fast path is optimized by avoiding a stack frame (and reloading the GP), register store and all this. This is only done in the slowpath. After marking the slowpath (atomic_dec_and_lock_1()) as "noinline" and doing the slowpath in C (the atomic_add_unless(atomic, -1, 1) part) I noticed differences in the resulting assembly: - the GP is still reloaded - atomic_add_unless() adds more memory barriers compared to the custom assembly - the custom assembly here does "load, sub, beq" while atomic_add_unless() does "load, cmpeq, add, bne". This is okay because it compares against zero after subtraction while the generic code compares against 1 before. I'm not sure if avoiding the stack frame (and GP reloading) brings a lot in terms of performance. Regarding the different barriers, Peter Zijlstra says: |refcount decrement needs to be a RELEASE operation, such that all the |load/stores to the object happen before we decrement the refcount. | |Otherwise things like: | | obj->foo = 5; | refcnt_dec(&obj->ref); | |can be re-ordered, which then allows fun scenarios like: | | CPU0 CPU1 | | refcnt_dec(&obj->ref); | if (dec_and_test(&obj->ref)) | free(obj); | obj->foo = 5; // oops UaF | | |This means (for alpha) that there should be a memory barrier _before_ |the decrement, however the dec_and_lock asm thing only has one _after_, |which, per the above, is too late. | |The generic version using add_unless will result in memory barrier |before and after (because that is the rule for atomic ops with a return |value) which is strictly too many barriers for the refcount story, but |who knows what other ordering requirements code has. Remove the custom alpha implementation of dec_and_lock() and if it is an issue (performance wise) then the fast path could still be inlined. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: linux-alpha@vger.kernel.org Link: https://lkml.kernel.org/r/20180606115918.GG12198@hirez.programming.kicks-ass.net Link: https://lkml.kernel.org/r20180612161621.22645-2-bigeasy@linutronix.de
266 lines
8.5 KiB
Makefile
266 lines
8.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for some libs needed in the kernel.
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#
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ifdef CONFIG_FUNCTION_TRACER
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ORIG_CFLAGS := $(KBUILD_CFLAGS)
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KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
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endif
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# These files are disabled because they produce lots of non-interesting and/or
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# flaky coverage that is not a function of syscall inputs. For example,
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# rbtree can be global and individual rotations don't correlate with inputs.
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KCOV_INSTRUMENT_string.o := n
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KCOV_INSTRUMENT_rbtree.o := n
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KCOV_INSTRUMENT_list_debug.o := n
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KCOV_INSTRUMENT_debugobjects.o := n
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KCOV_INSTRUMENT_dynamic_debug.o := n
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lib-y := ctype.o string.o vsprintf.o cmdline.o \
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rbtree.o radix-tree.o timerqueue.o\
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idr.o int_sqrt.o extable.o \
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sha1.o chacha20.o irq_regs.o argv_split.o \
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flex_proportions.o ratelimit.o show_mem.o \
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is_single_threaded.o plist.o decompress.o kobject_uevent.o \
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earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
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nmi_backtrace.o nodemask.o win_minmax.o
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lib-$(CONFIG_PRINTK) += dump_stack.o
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lib-$(CONFIG_MMU) += ioremap.o
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lib-$(CONFIG_SMP) += cpumask.o
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lib-$(CONFIG_DMA_DIRECT_OPS) += dma-direct.o
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lib-$(CONFIG_DMA_NONCOHERENT_OPS) += dma-noncoherent.o
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lib-$(CONFIG_DMA_VIRT_OPS) += dma-virt.o
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lib-y += kobject.o klist.o
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obj-y += lockref.o
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obj-y += bcd.o div64.o sort.o parser.o debug_locks.o random32.o \
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bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
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gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
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bsearch.o find_bit.o llist.o memweight.o kfifo.o \
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percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o \
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once.o refcount.o usercopy.o errseq.o bucket_locks.o
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obj-$(CONFIG_STRING_SELFTEST) += test_string.o
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obj-y += string_helpers.o
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obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
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obj-y += hexdump.o
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obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o
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obj-y += kstrtox.o
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obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o
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obj-$(CONFIG_TEST_BPF) += test_bpf.o
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obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o
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obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o
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obj-$(CONFIG_TEST_HASH) += test_hash.o test_siphash.o
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obj-$(CONFIG_TEST_KASAN) += test_kasan.o
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CFLAGS_test_kasan.o += -fno-builtin
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obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
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UBSAN_SANITIZE_test_ubsan.o := y
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obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
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obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
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obj-$(CONFIG_TEST_LKM) += test_module.o
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obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.o
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obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
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obj-$(CONFIG_TEST_SORT) += test_sort.o
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obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
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obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
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obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
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obj-$(CONFIG_TEST_PRINTF) += test_printf.o
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obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
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obj-$(CONFIG_TEST_UUID) += test_uuid.o
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obj-$(CONFIG_TEST_PARMAN) += test_parman.o
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obj-$(CONFIG_TEST_KMOD) += test_kmod.o
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obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
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ifeq ($(CONFIG_DEBUG_KOBJECT),y)
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CFLAGS_kobject.o += -DDEBUG
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CFLAGS_kobject_uevent.o += -DDEBUG
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endif
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obj-$(CONFIG_DEBUG_INFO_REDUCED) += debug_info.o
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CFLAGS_debug_info.o += $(call cc-option, -femit-struct-debug-detailed=any)
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obj-$(CONFIG_GENERIC_IOMAP) += iomap.o
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obj-$(CONFIG_GENERIC_PCI_IOMAP) += pci_iomap.o
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obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o
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obj-$(CONFIG_CHECK_SIGNATURE) += check_signature.o
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obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o
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obj-y += logic_pio.o
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obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
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obj-$(CONFIG_BTREE) += btree.o
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obj-$(CONFIG_INTERVAL_TREE) += interval_tree.o
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obj-$(CONFIG_ASSOCIATIVE_ARRAY) += assoc_array.o
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obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
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obj-$(CONFIG_DEBUG_LIST) += list_debug.o
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obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o
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obj-$(CONFIG_BITREVERSE) += bitrev.o
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obj-$(CONFIG_RATIONAL) += rational.o
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obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o
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obj-$(CONFIG_CRC16) += crc16.o
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obj-$(CONFIG_CRC_T10DIF)+= crc-t10dif.o
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obj-$(CONFIG_CRC_ITU_T) += crc-itu-t.o
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obj-$(CONFIG_CRC32) += crc32.o
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obj-$(CONFIG_CRC32_SELFTEST) += crc32test.o
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obj-$(CONFIG_CRC4) += crc4.o
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obj-$(CONFIG_CRC7) += crc7.o
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obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
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obj-$(CONFIG_CRC8) += crc8.o
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obj-$(CONFIG_XXHASH) += xxhash.o
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obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
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obj-$(CONFIG_842_COMPRESS) += 842/
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obj-$(CONFIG_842_DECOMPRESS) += 842/
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obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/
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obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate/
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obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
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obj-$(CONFIG_BCH) += bch.o
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obj-$(CONFIG_LZO_COMPRESS) += lzo/
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obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
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obj-$(CONFIG_LZ4_COMPRESS) += lz4/
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obj-$(CONFIG_LZ4HC_COMPRESS) += lz4/
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obj-$(CONFIG_LZ4_DECOMPRESS) += lz4/
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obj-$(CONFIG_ZSTD_COMPRESS) += zstd/
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obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd/
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obj-$(CONFIG_XZ_DEC) += xz/
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obj-$(CONFIG_RAID6_PQ) += raid6/
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lib-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o
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lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
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lib-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o
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lib-$(CONFIG_DECOMPRESS_XZ) += decompress_unxz.o
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lib-$(CONFIG_DECOMPRESS_LZO) += decompress_unlzo.o
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lib-$(CONFIG_DECOMPRESS_LZ4) += decompress_unlz4.o
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obj-$(CONFIG_TEXTSEARCH) += textsearch.o
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obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o
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obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o
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obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o
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obj-$(CONFIG_SMP) += percpu_counter.o
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obj-$(CONFIG_AUDIT_GENERIC) += audit.o
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obj-$(CONFIG_AUDIT_COMPAT_GENERIC) += compat_audit.o
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obj-$(CONFIG_SWIOTLB) += swiotlb.o
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obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
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obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
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obj-$(CONFIG_NOTIFIER_ERROR_INJECTION) += notifier-error-inject.o
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obj-$(CONFIG_PM_NOTIFIER_ERROR_INJECT) += pm-notifier-error-inject.o
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obj-$(CONFIG_NETDEV_NOTIFIER_ERROR_INJECT) += netdev-notifier-error-inject.o
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obj-$(CONFIG_MEMORY_NOTIFIER_ERROR_INJECT) += memory-notifier-error-inject.o
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obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \
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of-reconfig-notifier-error-inject.o
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obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
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lib-$(CONFIG_GENERIC_BUG) += bug.o
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obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
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obj-$(CONFIG_DYNAMIC_DEBUG) += dynamic_debug.o
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obj-$(CONFIG_NLATTR) += nlattr.o
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obj-$(CONFIG_LRU_CACHE) += lru_cache.o
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obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o
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obj-$(CONFIG_GENERIC_CSUM) += checksum.o
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obj-$(CONFIG_GENERIC_ATOMIC64) += atomic64.o
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obj-$(CONFIG_ATOMIC64_SELFTEST) += atomic64_test.o
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obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o
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obj-$(CONFIG_CORDIC) += cordic.o
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obj-$(CONFIG_DQL) += dynamic_queue_limits.o
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obj-$(CONFIG_GLOB) += glob.o
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obj-$(CONFIG_GLOB_SELFTEST) += globtest.o
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obj-$(CONFIG_MPILIB) += mpi/
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obj-$(CONFIG_SIGNATURE) += digsig.o
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lib-$(CONFIG_CLZ_TAB) += clz_tab.o
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obj-$(CONFIG_DDR) += jedec_ddr_data.o
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obj-$(CONFIG_GENERIC_STRNCPY_FROM_USER) += strncpy_from_user.o
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obj-$(CONFIG_GENERIC_STRNLEN_USER) += strnlen_user.o
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obj-$(CONFIG_GENERIC_NET_UTILS) += net_utils.o
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obj-$(CONFIG_SG_SPLIT) += sg_split.o
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obj-$(CONFIG_SG_POOL) += sg_pool.o
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obj-$(CONFIG_STMP_DEVICE) += stmp_device.o
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obj-$(CONFIG_IRQ_POLL) += irq_poll.o
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obj-$(CONFIG_STACKDEPOT) += stackdepot.o
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KASAN_SANITIZE_stackdepot.o := n
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KCOV_INSTRUMENT_stackdepot.o := n
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libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o \
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fdt_empty_tree.o
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$(foreach file, $(libfdt_files), \
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$(eval CFLAGS_$(file) = -I$(src)/../scripts/dtc/libfdt))
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lib-$(CONFIG_LIBFDT) += $(libfdt_files)
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obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
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obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
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obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
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obj-$(CONFIG_ASN1) += asn1_decoder.o
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obj-$(CONFIG_FONT_SUPPORT) += fonts/
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obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o
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hostprogs-y := gen_crc32table
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clean-files := crc32table.h
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$(obj)/crc32.o: $(obj)/crc32table.h
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quiet_cmd_crc32 = GEN $@
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cmd_crc32 = $< > $@
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$(obj)/crc32table.h: $(obj)/gen_crc32table
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$(call cmd,crc32)
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#
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# Build a fast OID lookip registry from include/linux/oid_registry.h
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#
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obj-$(CONFIG_OID_REGISTRY) += oid_registry.o
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$(obj)/oid_registry.o: $(obj)/oid_registry_data.c
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$(obj)/oid_registry_data.c: $(srctree)/include/linux/oid_registry.h \
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$(src)/build_OID_registry
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$(call cmd,build_OID_registry)
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quiet_cmd_build_OID_registry = GEN $@
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cmd_build_OID_registry = perl $(srctree)/$(src)/build_OID_registry $< $@
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clean-files += oid_registry_data.c
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obj-$(CONFIG_UCS2_STRING) += ucs2_string.o
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obj-$(CONFIG_UBSAN) += ubsan.o
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UBSAN_SANITIZE_ubsan.o := n
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obj-$(CONFIG_SBITMAP) += sbitmap.o
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obj-$(CONFIG_PARMAN) += parman.o
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# GCC library routines
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obj-$(CONFIG_GENERIC_ASHLDI3) += ashldi3.o
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obj-$(CONFIG_GENERIC_ASHRDI3) += ashrdi3.o
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obj-$(CONFIG_GENERIC_LSHRDI3) += lshrdi3.o
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obj-$(CONFIG_GENERIC_MULDI3) += muldi3.o
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obj-$(CONFIG_GENERIC_CMPDI2) += cmpdi2.o
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obj-$(CONFIG_GENERIC_UCMPDI2) += ucmpdi2.o
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