1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __ASM_ARM_WORD_AT_A_TIME_H 3 #define __ASM_ARM_WORD_AT_A_TIME_H 4 5 #ifndef __ARMEB__ 6 7 /* 8 * Little-endian word-at-a-time zero byte handling. 9 * Heavily based on the x86 algorithm. 10 */ 11 #include <linux/bitops.h> 12 #include <linux/wordpart.h> 13 14 struct word_at_a_time { 15 const unsigned long one_bits, high_bits; 16 }; 17 18 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } 19 20 static inline unsigned long has_zero(unsigned long a, unsigned long *bits, 21 const struct word_at_a_time *c) 22 { 23 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits; 24 *bits = mask; 25 return mask; 26 } 27 28 #define prep_zero_mask(a, bits, c) (bits) 29 30 static inline unsigned long create_zero_mask(unsigned long bits) 31 { 32 bits = (bits - 1) & ~bits; 33 return bits >> 7; 34 } 35 36 static inline unsigned long find_zero(unsigned long mask) 37 { 38 unsigned long ret; 39 40 #if __LINUX_ARM_ARCH__ >= 5 41 /* We have clz available. */ 42 ret = fls(mask) >> 3; 43 #else 44 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ 45 ret = (0x0ff0001 + mask) >> 23; 46 /* Fix the 1 for 00 case */ 47 ret &= mask; 48 #endif 49 50 return ret; 51 } 52 53 #define zero_bytemask(mask) (mask) 54 55 #else /* __ARMEB__ */ 56 #include <asm-generic/word-at-a-time.h> 57 #endif 58 59 #ifdef CONFIG_DCACHE_WORD_ACCESS 60 61 /* 62 * Load an unaligned word from kernel space. 63 * 64 * In the (very unlikely) case of the word being a page-crosser 65 * and the next page not being mapped, take the exception and 66 * return zeroes in the non-existing part. 67 */ 68 static inline unsigned long load_unaligned_zeropad(const void *addr) 69 { 70 unsigned long ret, offset; 71 72 /* Load word from unaligned pointer addr */ 73 asm( 74 "1: ldr %0, [%2]\n" 75 "2:\n" 76 " .pushsection .text.fixup,\"ax\"\n" 77 " .align 2\n" 78 "3: and %1, %2, #0x3\n" 79 " bic %2, %2, #0x3\n" 80 " ldr %0, [%2]\n" 81 " lsl %1, %1, #0x3\n" 82 #ifndef __ARMEB__ 83 " lsr %0, %0, %1\n" 84 #else 85 " lsl %0, %0, %1\n" 86 #endif 87 " b 2b\n" 88 " .popsection\n" 89 " .pushsection __ex_table,\"a\"\n" 90 " .align 3\n" 91 " .long 1b, 3b\n" 92 " .popsection" 93 : "=&r" (ret), "=&r" (offset) 94 : "r" (addr), "Qo" (*(unsigned long *)addr)); 95 96 return ret; 97 } 98 99 #endif /* DCACHE_WORD_ACCESS */ 100 #endif /* __ASM_ARM_WORD_AT_A_TIME_H */ 101