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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/loongarch/kernel/relocate_kernel.S
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/* SPDX-License-Identifier: GPL-2.0 */

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/*

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 * relocate_kernel.S for kexec

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 *

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 * Copyright (C) 2022 Loongson Technology Corporation Limited

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 */

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#include <linux/kexec.h>

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#include <asm/asm.h>

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#include <asm/asmmacro.h>

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#include <asm/regdef.h>

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#include <asm/loongarch.h>

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#include <asm/stackframe.h>

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#include <asm/addrspace.h>

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SYM_CODE_START(relocate_new_kernel)

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	UNWIND_HINT_UNDEFINED

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	/*

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	 * a0: EFI boot flag for the new kernel

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	 * a1: Command line pointer for the new kernel

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	 * a2: System table pointer for the new kernel

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	 * a3: Start address to jump to after relocation

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	 * a4: Pointer to the current indirection page entry

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	 */

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	move		s0, a4

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	/*

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	 * In case of a kdump/crash kernel, the indirection page is not

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	 * populated as the kernel is directly copied to a reserved location

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	 */

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	beqz		s0, done

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process_entry:

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	PTR_L		s1, s0, 0

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	PTR_ADDI	s0, s0, SZREG

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	/* destination page */

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	andi		s2, s1, IND_DESTINATION

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	beqz		s2, 1f

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	li.w		t0, ~0x1

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	and		s3, s1, t0	/* store destination addr in s3 */

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	b		process_entry

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1:

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	/* indirection page, update s0	*/

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	andi		s2, s1, IND_INDIRECTION

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	beqz		s2, 1f

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	li.w		t0, ~0x2

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	and		s0, s1, t0

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	b		process_entry

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1:

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	/* done page */

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	andi		s2, s1, IND_DONE

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	beqz		s2, 1f

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	b		done

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1:

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	/* source page */

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	andi		s2, s1, IND_SOURCE

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	beqz		s2, process_entry

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	li.w		t0, ~0x8

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	and		s1, s1, t0

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	li.w		s5, (1 << _PAGE_SHIFT) / SZREG

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copy_word:

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	/* copy page word by word */

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	REG_L		s4, s1, 0

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	REG_S		s4, s3, 0

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	PTR_ADDI	s3, s3, SZREG

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	PTR_ADDI	s1, s1, SZREG

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	LONG_ADDI	s5, s5, -1

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	beqz		s5, process_entry

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	b		copy_word

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done:

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	ibar		0

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	dbar		0

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	/*

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	 * Jump to the new kernel,

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	 * make sure the values of a0, a1, a2 and a3 are not changed.

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	 */

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	jr		a3

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SYM_CODE_END(relocate_new_kernel)

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#ifdef CONFIG_SMP

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/*

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 * Other CPUs should wait until code is relocated and

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 * then start at the entry point from LOONGARCH_IOCSR_MBUF0.

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 */

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SYM_CODE_START(kexec_smp_wait)

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	UNWIND_HINT_UNDEFINED

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1:	li.w		t0, 0x100			/* wait for init loop */

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2:	addi.w		t0, t0, -1			/* limit mailbox access */

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	bnez		t0, 2b

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	li.w		t1, LOONGARCH_IOCSR_MBUF0

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	iocsrrd.w	s0, t1				/* check PC as an indicator */

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	beqz		s0, 1b

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	iocsrrd.d	s0, t1				/* get PC via mailbox */

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	li.d		t0, CACHE_BASE

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	or		s0, s0, t0			/* s0 = TO_CACHE(s0) */

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	jr		s0				/* jump to initial PC */

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SYM_CODE_END(kexec_smp_wait)

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#endif

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relocate_new_kernel_end:

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	.section ".data"

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SYM_DATA(relocate_new_kernel_size, .quad relocate_new_kernel_end - relocate_new_kernel)

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