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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/riscv/lib/clear_page.S
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/* SPDX-License-Identifier: GPL-2.0-only */

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/*

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 * Copyright (c) 2023 Ventana Micro Systems Inc.

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 */

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#include <linux/linkage.h>

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#include <linux/export.h>

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#include <asm/asm.h>

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#include <asm/alternative-macros.h>

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#include <asm/hwcap.h>

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#include <asm/insn-def.h>

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#include <asm/page.h>

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#define CBOZ_ALT(order, old, new)				\

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	ALTERNATIVE(old, new, 0,				\

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		    ((order) << 16) | RISCV_ISA_EXT_ZICBOZ,	\

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		    CONFIG_RISCV_ISA_ZICBOZ)

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/* void clear_page(void *page) */

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SYM_FUNC_START(clear_page)

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	li	a2, PAGE_SIZE

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	/*

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	 * If Zicboz isn't present, or somehow has a block

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	 * size larger than 4K, then fallback to memset.

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	 */

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	CBOZ_ALT(12, "j .Lno_zicboz", "nop")

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	lw	a1, riscv_cboz_block_size

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	add	a2, a0, a2

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.Lzero_loop:

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBOZ_ALT(11, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBOZ_ALT(10, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBOZ_ALT(9, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBOZ_ALT(8, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	CBO_ZERO(a0)

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	add	a0, a0, a1

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	bltu	a0, a2, .Lzero_loop

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	ret

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.Lno_zicboz:

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	li	a1, 0

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	tail	__memset

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SYM_FUNC_END(clear_page)

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EXPORT_SYMBOL(clear_page)

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