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
  23 struct 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
  29 static 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
  39 static inline unsigned long create_zero_mask(unsigned long bits)
  40 {
  41         bits = (bits - 1) & ~bits;
  42         return bits >> 7;
  43 }
  44
  45 static 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  */
  63 static 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 */