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99 lines
2.1 KiB
99 lines
2.1 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __ASM_ARM_WORD_AT_A_TIME_H |
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#define __ASM_ARM_WORD_AT_A_TIME_H |
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#ifndef __ARMEB__ |
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/* |
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* Little-endian word-at-a-time zero byte handling. |
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* Heavily based on the x86 algorithm. |
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*/ |
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#include <linux/kernel.h> |
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struct word_at_a_time { |
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const unsigned long one_bits, high_bits; |
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}; |
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#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } |
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static inline unsigned long has_zero(unsigned long a, unsigned long *bits, |
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const struct word_at_a_time *c) |
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{ |
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unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits; |
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*bits = mask; |
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return mask; |
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} |
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#define prep_zero_mask(a, bits, c) (bits) |
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static inline unsigned long create_zero_mask(unsigned long bits) |
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{ |
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bits = (bits - 1) & ~bits; |
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return bits >> 7; |
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} |
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static inline unsigned long find_zero(unsigned long mask) |
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{ |
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unsigned long ret; |
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#if __LINUX_ARM_ARCH__ >= 5 |
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/* We have clz available. */ |
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ret = fls(mask) >> 3; |
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#else |
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/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ |
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ret = (0x0ff0001 + mask) >> 23; |
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/* Fix the 1 for 00 case */ |
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ret &= mask; |
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#endif |
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return ret; |
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} |
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#define zero_bytemask(mask) (mask) |
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#else /* __ARMEB__ */ |
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#include <asm-generic/word-at-a-time.h> |
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#endif |
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#ifdef CONFIG_DCACHE_WORD_ACCESS |
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/* |
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* Load an unaligned word from kernel space. |
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* |
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* In the (very unlikely) case of the word being a page-crosser |
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* and the next page not being mapped, take the exception and |
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* return zeroes in the non-existing part. |
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*/ |
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static inline unsigned long load_unaligned_zeropad(const void *addr) |
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{ |
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unsigned long ret, offset; |
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/* Load word from unaligned pointer addr */ |
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asm( |
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"1: ldr %0, [%2]\n" |
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"2:\n" |
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" .pushsection .text.fixup,\"ax\"\n" |
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" .align 2\n" |
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"3: and %1, %2, #0x3\n" |
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" bic %2, %2, #0x3\n" |
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" ldr %0, [%2]\n" |
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" lsl %1, %1, #0x3\n" |
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#ifndef __ARMEB__ |
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" lsr %0, %0, %1\n" |
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#else |
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" lsl %0, %0, %1\n" |
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#endif |
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" b 2b\n" |
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" .popsection\n" |
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" .pushsection __ex_table,\"a\"\n" |
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" .align 3\n" |
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" .long 1b, 3b\n" |
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" .popsection" |
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: "=&r" (ret), "=&r" (offset) |
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: "r" (addr), "Qo" (*(unsigned long *)addr)); |
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return ret; |
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} |
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#endif /* DCACHE_WORD_ACCESS */ |
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#endif /* __ASM_ARM_WORD_AT_A_TIME_H */
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