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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clear_page.S (724B)

      1/* SPDX-License-Identifier: GPL-2.0-only */
      2/*
      3 * Copyright (C) 2012 ARM Ltd.
      4 */
      5
      6#include <linux/linkage.h>
      7#include <linux/const.h>
      8#include <asm/assembler.h>
      9#include <asm/page.h>
     10
     11/*
     12 * Clear page @dest
     13 *
     14 * Parameters:
     15 *	x0 - dest
     16 */
     17SYM_FUNC_START(__pi_clear_page)
     18	mrs	x1, dczid_el0
     19	tbnz	x1, #4, 2f	/* Branch if DC ZVA is prohibited */
     20	and	w1, w1, #0xf
     21	mov	x2, #4
     22	lsl	x1, x2, x1
     23
     241:	dc	zva, x0
     25	add	x0, x0, x1
     26	tst	x0, #(PAGE_SIZE - 1)
     27	b.ne	1b
     28	ret
     29
     302:	stnp	xzr, xzr, [x0]
     31	stnp	xzr, xzr, [x0, #16]
     32	stnp	xzr, xzr, [x0, #32]
     33	stnp	xzr, xzr, [x0, #48]
     34	add	x0, x0, #64
     35	tst	x0, #(PAGE_SIZE - 1)
     36	b.ne	2b
     37	ret
     38SYM_FUNC_END(__pi_clear_page)
     39SYM_FUNC_ALIAS(clear_page, __pi_clear_page)
     40EXPORT_SYMBOL(clear_page)