185f2e5f51
The inline asm's addr operand is marked as input-only, however in the case where an exception is taken it may be modified by the BIC instruction on the exception path. Fix the problem by using a temporary register as the destination register for the BIC instruction. Signed-off-by: Peter Collingbourne <pcc@google.com> Cc: stable@vger.kernel.org Link: https://linux-review.googlesource.com/id/I84538c8a2307d567b4f45bb20b715451005f9617 Link: https://lore.kernel.org/r/20210401165110.3952103-1-pcc@google.com Signed-off-by: Will Deacon <will@kernel.org>
83 lines
1.7 KiB
C
83 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2013 ARM Ltd.
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*/
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#ifndef __ASM_WORD_AT_A_TIME_H
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#define __ASM_WORD_AT_A_TIME_H
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#include <linux/uaccess.h>
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#ifndef __AARCH64EB__
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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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return fls64(mask) >> 3;
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}
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#define zero_bytemask(mask) (mask)
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#else /* __AARCH64EB__ */
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#include <asm-generic/word-at-a-time.h>
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#endif
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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, tmp;
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/* Load word from unaligned pointer addr */
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asm(
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"1: ldr %0, %3\n"
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"2:\n"
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" .pushsection .fixup,\"ax\"\n"
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" .align 2\n"
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"3: bic %1, %2, #0x7\n"
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" ldr %0, [%1]\n"
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" and %1, %2, #0x7\n"
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" lsl %1, %1, #0x3\n"
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#ifndef __AARCH64EB__
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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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_ASM_EXTABLE(1b, 3b)
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: "=&r" (ret), "=&r" (tmp)
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: "r" (addr), "Q" (*(unsigned long *)addr));
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return ret;
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}
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#endif /* __ASM_WORD_AT_A_TIME_H */
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