arch/ia64/lib/clear_page.S

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 1999-2002 Hewlett-Packard Co
 *	Stephane Eranian <eranian@hpl.hp.com>
 *	David Mosberger-Tang <davidm@hpl.hp.com>
 * Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
 *
 * 1/06/01 davidm	Tuned for Itanium.
 * 2/12/02 kchen	Tuned for both Itanium and McKinley
 * 3/08/02 davidm	Some more tweaking
 */

#include <linux/export.h>
#include <asm/asmmacro.h>
#include <asm/page.h>

#ifdef CONFIG_ITANIUM
# define L3_LINE_SIZE	64	// Itanium L3 line size
# define PREFETCH_LINES	9	// magic number
#else
# define L3_LINE_SIZE	128	// McKinley L3 line size
# define PREFETCH_LINES	12	// magic number
#endif

#define saved_lc	r2
#define dst_fetch	r3
#define dst1		r8
#define dst2		r9
#define dst3		r10
#define dst4		r11

#define dst_last	r31

GLOBAL_ENTRY(clear_page)
	.prologue
	.regstk 1,0,0,0
	mov r16 = PAGE_SIZE/L3_LINE_SIZE-1	// main loop count, -1=repeat/until
	.save ar.lc, saved_lc
	mov saved_lc = ar.lc

	.body
	mov ar.lc = (PREFETCH_LINES - 1)
	mov dst_fetch = in0
	adds dst1 = 16, in0
	adds dst2 = 32, in0
	;;
.fetch:	stf.spill.nta [dst_fetch] = f0, L3_LINE_SIZE
	adds dst3 = 48, in0		// executing this multiple times is harmless
	br.cloop.sptk.few .fetch
	;;
	addl dst_last = (PAGE_SIZE - PREFETCH_LINES*L3_LINE_SIZE), dst_fetch
	mov ar.lc = r16			// one L3 line per iteration
	adds dst4 = 64, in0
	;;
#ifdef CONFIG_ITANIUM
	// Optimized for Itanium
1:	stf.spill.nta [dst1] = f0, 64
	stf.spill.nta [dst2] = f0, 64
	cmp.lt p8,p0=dst_fetch, dst_last
	;;
#else
	// Optimized for McKinley
1:	stf.spill.nta [dst1] = f0, 64
	stf.spill.nta [dst2] = f0, 64
	stf.spill.nta [dst3] = f0, 64
	stf.spill.nta [dst4] = f0, 128
	cmp.lt p8,p0=dst_fetch, dst_last
	;;
	stf.spill.nta [dst1] = f0, 64
	stf.spill.nta [dst2] = f0, 64
#endif
	stf.spill.nta [dst3] = f0, 64
(p8)	stf.spill.nta [dst_fetch] = f0, L3_LINE_SIZE
	br.cloop.sptk.few 1b
	;;
	mov ar.lc = saved_lc		// restore lc
	br.ret.sptk.many rp
END(clear_page)
EXPORT_SYMBOL(clear_page)