cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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word-at-a-time.h (2134B)

      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
     13struct 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
     19static 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
     29static inline unsigned long create_zero_mask(unsigned long bits)
     30{
     31	bits = (bits - 1) & ~bits;
     32	return bits >> 7;
     33}
     34
     35static 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 */
     67static 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 */