From f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 8 Dec 2006 02:37:49 -0800 Subject: [PATCH] LOG2: Implement a general integer log2 facility in the kernel This facility provides three entry points: ilog2() Log base 2 of unsigned long ilog2_u32() Log base 2 of u32 ilog2_u64() Log base 2 of u64 These facilities can either be used inside functions on dynamic data: int do_something(long q) { ...; y = ilog2(x) ...; } Or can be used to statically initialise global variables with constant values: unsigned n = ilog2(27); When performing static initialisation, the compiler will report "error: initializer element is not constant" if asked to take a log of zero or of something not reducible to a constant. They treat negative numbers as unsigned. When not dealing with a constant, they fall back to using fls() which permits them to use arch-specific log calculation instructions - such as BSR on x86/x86_64 or SCAN on FRV - if available. [akpm@osdl.org: MMC fix] Signed-off-by: David Howells Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Herbert Xu Cc: David Howells Cc: Wojtek Kaniewski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/alpha/Kconfig | 8 ++ arch/arm/Kconfig | 8 ++ arch/arm26/Kconfig | 8 ++ arch/avr32/Kconfig | 8 ++ arch/cris/Kconfig | 8 ++ arch/frv/Kconfig | 8 ++ arch/h8300/Kconfig | 8 ++ arch/i386/Kconfig.cpu | 8 ++ arch/ia64/Kconfig | 8 ++ arch/m32r/Kconfig | 8 ++ arch/m68k/Kconfig | 8 ++ arch/m68knommu/Kconfig | 8 ++ arch/mips/Kconfig | 8 ++ arch/parisc/Kconfig | 8 ++ arch/powerpc/Kconfig | 8 ++ arch/ppc/Kconfig | 8 ++ arch/s390/Kconfig | 8 ++ arch/sh/Kconfig | 8 ++ arch/sh64/Kconfig | 8 ++ arch/sparc/Kconfig | 8 ++ arch/sparc64/Kconfig | 8 ++ arch/v850/Kconfig | 8 ++ arch/x86_64/Kconfig | 8 ++ arch/xtensa/Kconfig | 8 ++ drivers/infiniband/hw/mthca/mthca_provider.c | 4 +- drivers/infiniband/hw/mthca/mthca_qp.c | 4 +- drivers/infiniband/hw/mthca/mthca_srq.c | 4 +- drivers/infiniband/ulp/iser/iser_memory.c | 4 +- drivers/md/dm-crypt.c | 2 +- drivers/mmc/tifm_sd.c | 2 +- fs/ext2/super.c | 6 +- fs/ext3/super.c | 6 +- include/asm-frv/bitops.h | 44 +++++++++ include/linux/kernel.h | 9 +- include/linux/log2.h | 131 +++++++++++++++++++++++++++ mm/page_alloc.c | 4 +- 36 files changed, 384 insertions(+), 28 deletions(-) create mode 100644 include/linux/log2.h diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 7e55ea66c6d4..84caf50725b5 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8c05d4321ae9..aa1d400d721a 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -74,6 +74,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/arm26/Kconfig b/arch/arm26/Kconfig index c14fe918bc4c..74eba8b5a8ca 100644 --- a/arch/arm26/Kconfig +++ b/arch/arm26/Kconfig @@ -41,6 +41,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig index 5f1694eea842..bb059a4e1df9 100644 --- a/arch/avr32/Kconfig +++ b/arch/avr32/Kconfig @@ -45,6 +45,14 @@ config GENERIC_TIME config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_BUST_SPINLOCK bool diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig index 6a1238a29d6c..3474309e049c 100644 --- a/arch/cris/Kconfig +++ b/arch/cris/Kconfig @@ -16,6 +16,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig index cf1c446e003a..7561d7b72e75 100644 --- a/arch/frv/Kconfig +++ b/arch/frv/Kconfig @@ -41,6 +41,14 @@ config TIME_LOW_RES bool default y +config ARCH_HAS_ILOG2_U32 + bool + default y + +config ARCH_HAS_ILOG2_U64 + bool + default y + mainmenu "Fujitsu FR-V Kernel Configuration" source "init/Kconfig" diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig index cabf0bfffc53..34a84bc4baf5 100644 --- a/arch/h8300/Kconfig +++ b/arch/h8300/Kconfig @@ -29,6 +29,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/i386/Kconfig.cpu b/arch/i386/Kconfig.cpu index 821fd269ca58..2aecfba4ac4f 100644 --- a/arch/i386/Kconfig.cpu +++ b/arch/i386/Kconfig.cpu @@ -248,6 +248,14 @@ config RWSEM_XCHGADD_ALGORITHM depends on !M386 default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_CALIBRATE_DELAY bool default y diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 75d839715b2f..fcacfe291b9b 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -34,6 +34,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig index 41fd490af3b4..f383dab973f5 100644 --- a/arch/m32r/Kconfig +++ b/arch/m32r/Kconfig @@ -214,6 +214,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index 7bc14461a6ac..70a577c89c7c 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -17,6 +17,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig index aa70dde54228..25993c2a8fbb 100644 --- a/arch/m68knommu/Kconfig +++ b/arch/m68knommu/Kconfig @@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index d8af858fe3f5..57af8d8cf46f 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -819,6 +819,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index d2101237442e..0f9ff618c6d7 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -25,6 +25,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 291c95ac4b31..97c7a212cdda 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -41,6 +41,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig index f76a146cff13..692b5ba53209 100644 --- a/arch/ppc/Kconfig +++ b/arch/ppc/Kconfig @@ -19,6 +19,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default y + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 583d9ff0a571..45e47bfb68a9 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -22,6 +22,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index d83d64af31f2..8e24c40662e3 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -59,6 +59,14 @@ config LOCKDEP_SUPPORT bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" menu "System type" diff --git a/arch/sh64/Kconfig b/arch/sh64/Kconfig index 58c678e06667..7bc0744b7ab6 100644 --- a/arch/sh64/Kconfig +++ b/arch/sh64/Kconfig @@ -39,6 +39,14 @@ config RWSEM_XCHGADD_ALGORITHM config GENERIC_ISA_DMA bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source init/Kconfig menu "System type" diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 92a7c8a636d3..d0dec1ea2eed 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -166,6 +166,14 @@ config ARCH_MAY_HAVE_PC_FDC bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config SUN_PM bool default y diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig index b627f8dbcaad..d391d11f245a 100644 --- a/arch/sparc64/Kconfig +++ b/arch/sparc64/Kconfig @@ -34,6 +34,14 @@ config ARCH_MAY_HAVE_PC_FDC bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config AUDIT_ARCH bool default y diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig index 37ec644603ab..bcf825875d17 100644 --- a/arch/v850/Kconfig +++ b/arch/v850/Kconfig @@ -38,6 +38,14 @@ config TIME_LOW_RES bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + # Turn off some random 386 crap that can affect device config config ISA bool diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig index 3254a616c69e..3ac581d17202 100644 --- a/arch/x86_64/Kconfig +++ b/arch/x86_64/Kconfig @@ -101,6 +101,14 @@ config GENERIC_BUG default y depends on BUG +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index c1e69a1f92a4..9eccfbd1b536 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -34,6 +34,14 @@ config GENERIC_HARDIRQS bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" menu "Processor type and features" diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c index 21422a3336ad..7ec7c4b937f9 100644 --- a/drivers/infiniband/hw/mthca/mthca_provider.c +++ b/drivers/infiniband/hw/mthca/mthca_provider.c @@ -124,7 +124,7 @@ static int mthca_query_device(struct ib_device *ibdev, props->max_map_per_fmr = 255; else props->max_map_per_fmr = - (1 << (32 - long_log2(mdev->limits.num_mpts))) - 1; + (1 << (32 - ilog2(mdev->limits.num_mpts))) - 1; err = 0; out: @@ -816,7 +816,7 @@ static int mthca_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *uda lkey = ucmd.lkey; } - ret = mthca_RESIZE_CQ(dev, cq->cqn, lkey, long_log2(entries), &status); + ret = mthca_RESIZE_CQ(dev, cq->cqn, lkey, ilog2(entries), &status); if (status) ret = -EINVAL; diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c index 33e3ba7937f1..d844a2569b47 100644 --- a/drivers/infiniband/hw/mthca/mthca_qp.c +++ b/drivers/infiniband/hw/mthca/mthca_qp.c @@ -636,11 +636,11 @@ int mthca_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, int attr_mask, if (mthca_is_memfree(dev)) { if (qp->rq.max) - qp_context->rq_size_stride = long_log2(qp->rq.max) << 3; + qp_context->rq_size_stride = ilog2(qp->rq.max) << 3; qp_context->rq_size_stride |= qp->rq.wqe_shift - 4; if (qp->sq.max) - qp_context->sq_size_stride = long_log2(qp->sq.max) << 3; + qp_context->sq_size_stride = ilog2(qp->sq.max) << 3; qp_context->sq_size_stride |= qp->sq.wqe_shift - 4; } diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c index 34d2c4768962..10684da33d58 100644 --- a/drivers/infiniband/hw/mthca/mthca_srq.c +++ b/drivers/infiniband/hw/mthca/mthca_srq.c @@ -120,7 +120,7 @@ static void mthca_arbel_init_srq_context(struct mthca_dev *dev, memset(context, 0, sizeof *context); - logsize = long_log2(srq->max); + logsize = ilog2(srq->max); context->state_logsize_srqn = cpu_to_be32(logsize << 24 | srq->srqn); context->lkey = cpu_to_be32(srq->mr.ibmr.lkey); context->db_index = cpu_to_be32(srq->db_index); @@ -213,7 +213,7 @@ int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd, if (!mthca_is_memfree(dev) && (ds > dev->limits.max_desc_sz)) return -EINVAL; - srq->wqe_shift = long_log2(ds); + srq->wqe_shift = ilog2(ds); srq->srqn = mthca_alloc(&dev->srq_table.alloc); if (srq->srqn == -1) diff --git a/drivers/infiniband/ulp/iser/iser_memory.c b/drivers/infiniband/ulp/iser/iser_memory.c index 5e122501fd80..3aedd59b8a84 100644 --- a/drivers/infiniband/ulp/iser/iser_memory.c +++ b/drivers/infiniband/ulp/iser/iser_memory.c @@ -114,7 +114,7 @@ int iser_start_rdma_unaligned_sg(struct iscsi_iser_cmd_task *iser_ctask, if (cmd_data_len > ISER_KMALLOC_THRESHOLD) mem = (void *)__get_free_pages(GFP_NOIO, - long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); + ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); else mem = kmalloc(cmd_data_len, GFP_NOIO); @@ -211,7 +211,7 @@ void iser_finalize_rdma_unaligned_sg(struct iscsi_iser_cmd_task *iser_ctask, if (cmd_data_len > ISER_KMALLOC_THRESHOLD) free_pages((unsigned long)mem_copy->copy_buf, - long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); + ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); else kfree(mem_copy->copy_buf); diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index a1086ee8cccd..96152868525b 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -220,7 +220,7 @@ static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti, const char *opts) { unsigned int bs = crypto_blkcipher_blocksize(cc->tfm); - int log = long_log2(bs); + int log = ilog2(bs); /* we need to calculate how far we must shift the sector count * to get the cipher block count, we use this shift in _gen */ diff --git a/drivers/mmc/tifm_sd.c b/drivers/mmc/tifm_sd.c index e846499a004c..f18ad998b3cb 100644 --- a/drivers/mmc/tifm_sd.c +++ b/drivers/mmc/tifm_sd.c @@ -387,7 +387,7 @@ static void tifm_sd_prepare_data(struct tifm_sd *card, struct mmc_command *cmd) writel(TIFM_FIFO_INT_SETALL, sock->addr + SOCK_DMA_FIFO_INT_ENABLE_CLEAR); - writel(long_log2(cmd->data->blksz) - 2, + writel(ilog2(cmd->data->blksz) - 2, sock->addr + SOCK_FIFO_PAGE_SIZE); writel(TIFM_FIFO_ENABLE, sock->addr + SOCK_FIFO_CONTROL); writel(TIFM_FIFO_INTMASK, sock->addr + SOCK_DMA_FIFO_INT_ENABLE_SET); diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 255cef5f7420..6347c2dbdd81 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -597,8 +597,6 @@ static int ext2_check_descriptors (struct super_block * sb) return 1; } -#define log2(n) ffz(~(n)) - /* * Maximal file size. There is a direct, and {,double-,triple-}indirect * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks. @@ -834,9 +832,9 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) sbi->s_sbh = bh; sbi->s_mount_state = le16_to_cpu(es->s_state); sbi->s_addr_per_block_bits = - log2 (EXT2_ADDR_PER_BLOCK(sb)); + ilog2 (EXT2_ADDR_PER_BLOCK(sb)); sbi->s_desc_per_block_bits = - log2 (EXT2_DESC_PER_BLOCK(sb)); + ilog2 (EXT2_DESC_PER_BLOCK(sb)); if (sb->s_magic != EXT2_SUPER_MAGIC) goto cantfind_ext2; diff --git a/fs/ext3/super.c b/fs/ext3/super.c index 580b8a6ca979..b34886734a44 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -1347,8 +1347,6 @@ static void ext3_orphan_cleanup (struct super_block * sb, sb->s_flags = s_flags; /* Restore MS_RDONLY status */ } -#define log2(n) ffz(~(n)) - /* * Maximal file size. There is a direct, and {,double-,triple-}indirect * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks. @@ -1597,8 +1595,8 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent) sbi->s_desc_per_block = blocksize / sizeof(struct ext3_group_desc); sbi->s_sbh = bh; sbi->s_mount_state = le16_to_cpu(es->s_state); - sbi->s_addr_per_block_bits = log2(EXT3_ADDR_PER_BLOCK(sb)); - sbi->s_desc_per_block_bits = log2(EXT3_DESC_PER_BLOCK(sb)); + sbi->s_addr_per_block_bits = ilog2(EXT3_ADDR_PER_BLOCK(sb)); + sbi->s_desc_per_block_bits = ilog2(EXT3_DESC_PER_BLOCK(sb)); for (i=0; i < 4; i++) sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]); sbi->s_def_hash_version = es->s_def_hash_version; diff --git a/include/asm-frv/bitops.h b/include/asm-frv/bitops.h index 1f70d47148bd..f8560edf59ff 100644 --- a/include/asm-frv/bitops.h +++ b/include/asm-frv/bitops.h @@ -256,6 +256,50 @@ int __ffs(unsigned long x) return 31 - bit; } +/* + * special slimline version of fls() for calculating ilog2_u32() + * - note: no protection against n == 0 + */ +#define ARCH_HAS_ILOG2_U32 +static inline __attribute__((const)) +int __ilog2_u32(u32 n) +{ + int bit; + asm("scan %1,gr0,%0" : "=r"(bit) : "r"(n)); + return 31 - bit; +} + +/* + * special slimline version of fls64() for calculating ilog2_u64() + * - note: no protection against n == 0 + */ +#define ARCH_HAS_ILOG2_U64 +static inline __attribute__((const)) +int __ilog2_u64(u64 n) +{ + union { + u64 ll; + struct { u32 h, l; }; + } _; + int bit, x, y; + + _.ll = n; + + asm(" subcc %3,gr0,gr0,icc0 \n" + " ckeq icc0,cc4 \n" + " cscan.p %3,gr0,%0 ,cc4,0 \n" + " setlos #63,%1 \n" + " cscan.p %4,gr0,%0 ,cc4,1 \n" + " setlos #31,%2 \n" + " csub.p %1,%0,%0 ,cc4,0 \n" + " csub %2,%0,%0 ,cc4,1 \n" + : "=&r"(bit), "=r"(x), "=r"(y) + : "0r"(_.h), "r"(_.l) + : "icc0", "cc4" + ); + return bit; +} + #include #include diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 6738283ac385..3710cce16642 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -13,6 +13,7 @@ #include #include #include +#include #include #include @@ -157,14 +158,6 @@ static inline int printk(const char *s, ...) { return 0; } unsigned long int_sqrt(unsigned long); -static inline int __attribute_pure__ long_log2(unsigned long x) -{ - int r = 0; - for (x >>= 1; x > 0; x >>= 1) - r++; - return r; -} - static inline unsigned long __attribute_const__ roundup_pow_of_two(unsigned long x) { diff --git a/include/linux/log2.h b/include/linux/log2.h new file mode 100644 index 000000000000..3979c60325ff --- /dev/null +++ b/include/linux/log2.h @@ -0,0 +1,131 @@ +/* Integer base 2 logarithm calculation + * + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#ifndef _LINUX_LOG2_H +#define _LINUX_LOG2_H + +#include +#include + +/* + * deal with unrepresentable constant logarithms + */ +extern __attribute__((const, noreturn)) +int ____ilog2_NaN(void); + +/* + * non-constant log of base 2 calculators + * - the arch may override these in asm/bitops.h if they can be implemented + * more efficiently than using fls() and fls64() + * - the arch is not required to handle n==0 if implementing the fallback + */ +#ifndef CONFIG_ARCH_HAS_ILOG2_U32 +static inline __attribute__((const)) +int __ilog2_u32(u32 n) +{ + return fls(n) - 1; +} +#endif + +#ifndef CONFIG_ARCH_HAS_ILOG2_U64 +static inline __attribute__((const)) +int __ilog2_u64(u64 n) +{ + return fls64(n) - 1; +} +#endif + +/** + * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value + * @n - parameter + * + * constant-capable log of base 2 calculation + * - this can be used to initialise global variables from constant data, hence + * the massive ternary operator construction + * + * selects the appropriately-sized optimised version depending on sizeof(n) + */ +#define ilog2(n) \ +( \ + __builtin_constant_p(n) ? ( \ + (n) < 1 ? ____ilog2_NaN() : \ + (n) & (1ULL << 63) ? 63 : \ + (n) & (1ULL << 62) ? 62 : \ + (n) & (1ULL << 61) ? 61 : \ + (n) & (1ULL << 60) ? 60 : \ + (n) & (1ULL << 59) ? 59 : \ + (n) & (1ULL << 58) ? 58 : \ + (n) & (1ULL << 57) ? 57 : \ + (n) & (1ULL << 56) ? 56 : \ + (n) & (1ULL << 55) ? 55 : \ + (n) & (1ULL << 54) ? 54 : \ + (n) & (1ULL << 53) ? 53 : \ + (n) & (1ULL << 52) ? 52 : \ + (n) & (1ULL << 51) ? 51 : \ + (n) & (1ULL << 50) ? 50 : \ + (n) & (1ULL << 49) ? 49 : \ + (n) & (1ULL << 48) ? 48 : \ + (n) & (1ULL << 47) ? 47 : \ + (n) & (1ULL << 46) ? 46 : \ + (n) & (1ULL << 45) ? 45 : \ + (n) & (1ULL << 44) ? 44 : \ + (n) & (1ULL << 43) ? 43 : \ + (n) & (1ULL << 42) ? 42 : \ + (n) & (1ULL << 41) ? 41 : \ + (n) & (1ULL << 40) ? 40 : \ + (n) & (1ULL << 39) ? 39 : \ + (n) & (1ULL << 38) ? 38 : \ + (n) & (1ULL << 37) ? 37 : \ + (n) & (1ULL << 36) ? 36 : \ + (n) & (1ULL << 35) ? 35 : \ + (n) & (1ULL << 34) ? 34 : \ + (n) & (1ULL << 33) ? 33 : \ + (n) & (1ULL << 32) ? 32 : \ + (n) & (1ULL << 31) ? 31 : \ + (n) & (1ULL << 30) ? 30 : \ + (n) & (1ULL << 29) ? 29 : \ + (n) & (1ULL << 28) ? 28 : \ + (n) & (1ULL << 27) ? 27 : \ + (n) & (1ULL << 26) ? 26 : \ + (n) & (1ULL << 25) ? 25 : \ + (n) & (1ULL << 24) ? 24 : \ + (n) & (1ULL << 23) ? 23 : \ + (n) & (1ULL << 22) ? 22 : \ + (n) & (1ULL << 21) ? 21 : \ + (n) & (1ULL << 20) ? 20 : \ + (n) & (1ULL << 19) ? 19 : \ + (n) & (1ULL << 18) ? 18 : \ + (n) & (1ULL << 17) ? 17 : \ + (n) & (1ULL << 16) ? 16 : \ + (n) & (1ULL << 15) ? 15 : \ + (n) & (1ULL << 14) ? 14 : \ + (n) & (1ULL << 13) ? 13 : \ + (n) & (1ULL << 12) ? 12 : \ + (n) & (1ULL << 11) ? 11 : \ + (n) & (1ULL << 10) ? 10 : \ + (n) & (1ULL << 9) ? 9 : \ + (n) & (1ULL << 8) ? 8 : \ + (n) & (1ULL << 7) ? 7 : \ + (n) & (1ULL << 6) ? 6 : \ + (n) & (1ULL << 5) ? 5 : \ + (n) & (1ULL << 4) ? 4 : \ + (n) & (1ULL << 3) ? 3 : \ + (n) & (1ULL << 2) ? 2 : \ + (n) & (1ULL << 1) ? 1 : \ + (n) & (1ULL << 0) ? 0 : \ + ____ilog2_NaN() \ + ) : \ + (sizeof(n) <= 4) ? \ + __ilog2_u32(n) : \ + __ilog2_u64(n) \ + ) + +#endif /* _LINUX_LOG2_H */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index cace22b3ac25..18f0e044c43d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3244,7 +3244,7 @@ void *__init alloc_large_system_hash(const char *tablename, if (numentries > max) numentries = max; - log2qty = long_log2(numentries); + log2qty = ilog2(numentries); do { size = bucketsize << log2qty; @@ -3266,7 +3266,7 @@ void *__init alloc_large_system_hash(const char *tablename, printk("%s hash table entries: %d (order: %d, %lu bytes)\n", tablename, (1U << log2qty), - long_log2(size) - PAGE_SHIFT, + ilog2(size) - PAGE_SHIFT, size); if (_hash_shift) -- cgit v1.2.3-59-g8ed1b