LXR linux/arch/arm64/include/asm/word-at-a-time.h

   1/*
   2 * Copyright (C) 2013 ARM Ltd.
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public License
  14 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15 */
  16#ifndef __ASM_WORD_AT_A_TIME_H
  17#define __ASM_WORD_AT_A_TIME_H
  18
  19#ifndef __AARCH64EB__
  20
  21#include <linux/kernel.h>
  22
  23struct word_at_a_time {
  24        const unsigned long one_bits, high_bits;
  25};
  26
  27#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
  28
  29static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
  30                                     const struct word_at_a_time *c)
  31{
  32        unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
  33        *bits = mask;
  34        return mask;
  35}
  36
  37#define prep_zero_mask(a, bits, c) (bits)
  38
  39static inline unsigned long create_zero_mask(unsigned long bits)
  40{
  41        bits = (bits - 1) & ~bits;
  42        return bits >> 7;
  43}
  44
  45static inline unsigned long find_zero(unsigned long mask)
  46{
  47        return fls64(mask) >> 3;
  48}
  49
  50#define zero_bytemask(mask) (mask)
  51
  52#else   /* __AARCH64EB__ */
  53#include <asm-generic/word-at-a-time.h>
  54#endif
  55
  56/*
  57 * Load an unaligned word from kernel space.
  58 *
  59 * In the (very unlikely) case of the word being a page-crosser
  60 * and the next page not being mapped, take the exception and
  61 * return zeroes in the non-existing part.
  62 */
  63static inline unsigned long load_unaligned_zeropad(const void *addr)
  64{
  65        unsigned long ret, offset;
  66
  67        /* Load word from unaligned pointer addr */
  68        asm(
  69        "1:     ldr     %0, %3\n"
  70        "2:\n"
  71        "       .pushsection .fixup,\"ax\"\n"
  72        "       .align 2\n"
  73        "3:     and     %1, %2, #0x7\n"
  74        "       bic     %2, %2, #0x7\n"
  75        "       ldr     %0, [%2]\n"
  76        "       lsl     %1, %1, #0x3\n"
  77#ifndef __AARCH64EB__
  78        "       lsr     %0, %0, %1\n"
  79#else
  80        "       lsl     %0, %0, %1\n"
  81#endif
  82        "       b       2b\n"
  83        "       .popsection\n"
  84        "       .pushsection __ex_table,\"a\"\n"
  85        "       .align  3\n"
  86        "       .quad   1b, 3b\n"
  87        "       .popsection"
  88        : "=&r" (ret), "=&r" (offset)
  89        : "r" (addr), "Q" (*(unsigned long *)addr));
  90
  91        return ret;
  92}
  93
  94#endif /* __ASM_WORD_AT_A_TIME_H */
  95