1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * relocate_kernel.S for kexec
4 *
5 * Copyright (C) 2022 Loongson Technology Corporation Limited
6 */
7
8#include <linux/kexec.h>
9
10#include <asm/asm.h>
11#include <asm/asmmacro.h>
12#include <asm/regdef.h>
13#include <asm/loongarch.h>
14#include <asm/stackframe.h>
15#include <asm/addrspace.h>
16
17SYM_CODE_START(relocate_new_kernel)
18	UNWIND_HINT_UNDEFINED
19	/*
20	 * a0: EFI boot flag for the new kernel
21	 * a1: Command line pointer for the new kernel
22	 * a2: System table pointer for the new kernel
23	 * a3: Start address to jump to after relocation
24	 * a4: Pointer to the current indirection page entry
25	 */
26	move		s0, a4
27
28	/*
29	 * In case of a kdump/crash kernel, the indirection page is not
30	 * populated as the kernel is directly copied to a reserved location
31	 */
32	beqz		s0, done
33
34process_entry:
35	PTR_L		s1, s0, 0
36	PTR_ADDI	s0, s0, SZREG
37
38	/* destination page */
39	andi		s2, s1, IND_DESTINATION
40	beqz		s2, 1f
41	li.w		t0, ~0x1
42	and		s3, s1, t0	/* store destination addr in s3 */
43	b		process_entry
44
451:
46	/* indirection page, update s0	*/
47	andi		s2, s1, IND_INDIRECTION
48	beqz		s2, 1f
49	li.w		t0, ~0x2
50	and		s0, s1, t0
51	b		process_entry
52
531:
54	/* done page */
55	andi		s2, s1, IND_DONE
56	beqz		s2, 1f
57	b		done
58
591:
60	/* source page */
61	andi		s2, s1, IND_SOURCE
62	beqz		s2, process_entry
63	li.w		t0, ~0x8
64	and		s1, s1, t0
65	li.w		s5, (1 << _PAGE_SHIFT) / SZREG
66
67copy_word:
68	/* copy page word by word */
69	REG_L		s4, s1, 0
70	REG_S		s4, s3, 0
71	PTR_ADDI	s3, s3, SZREG
72	PTR_ADDI	s1, s1, SZREG
73	LONG_ADDI	s5, s5, -1
74	beqz		s5, process_entry
75	b		copy_word
76
77done:
78	ibar		0
79	dbar		0
80
81	/*
82	 * Jump to the new kernel,
83	 * make sure the values of a0, a1, a2 and a3 are not changed.
84	 */
85	jr		a3
86SYM_CODE_END(relocate_new_kernel)
87
88#ifdef CONFIG_SMP
89/*
90 * Other CPUs should wait until code is relocated and
91 * then start at the entry point from LOONGARCH_IOCSR_MBUF0.
92 */
93SYM_CODE_START(kexec_smp_wait)
94	UNWIND_HINT_UNDEFINED
951:	li.w		t0, 0x100			/* wait for init loop */
962:	addi.w		t0, t0, -1			/* limit mailbox access */
97	bnez		t0, 2b
98	li.w		t1, LOONGARCH_IOCSR_MBUF0
99	iocsrrd.w	s0, t1				/* check PC as an indicator */
100	beqz		s0, 1b
101	iocsrrd.d	s0, t1				/* get PC via mailbox */
102
103	li.d		t0, CACHE_BASE
104	or		s0, s0, t0			/* s0 = TO_CACHE(s0) */
105	jr		s0				/* jump to initial PC */
106SYM_CODE_END(kexec_smp_wait)
107#endif
108
109relocate_new_kernel_end:
110
111	.section ".data"
112SYM_DATA(relocate_new_kernel_size, .long relocate_new_kernel_end - relocate_new_kernel)
113