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