1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * relocate_kernel.S for kexec
4 * Created by <nschichan@corp.free.fr> on Thu Oct 12 17:49:57 2006
5 */
6
7#include <asm/asm.h>
8#include <asm/asmmacro.h>
9#include <asm/regdef.h>
10#include <asm/mipsregs.h>
11#include <asm/stackframe.h>
12#include <asm/addrspace.h>
13
14#include <kernel-entry-init.h>
15
16LEAF(relocate_new_kernel)
17 PTR_L a0, arg0
18 PTR_L a1, arg1
19 PTR_L a2, arg2
20 PTR_L a3, arg3
21
22 PTR_L s0, kexec_indirection_page
23 PTR_L s1, kexec_start_address
24
25process_entry:
26 PTR_L s2, (s0)
27 PTR_ADDIU s0, s0, SZREG
28
29 /*
30 * In case of a kdump/crash kernel, the indirection page is not
31 * populated as the kernel is directly copied to a reserved location
32 */
33 beqz s2, done
34
35 /* destination page */
36 and s3, s2, 0x1
37 beq s3, zero, 1f
38 and s4, s2, ~0x1 /* store destination addr in s4 */
39 b process_entry
40
411:
42 /* indirection page, update s0 */
43 and s3, s2, 0x2
44 beq s3, zero, 1f
45 and s0, s2, ~0x2
46 b process_entry
47
481:
49 /* done page */
50 and s3, s2, 0x4
51 beq s3, zero, 1f
52 b done
531:
54 /* source page */
55 and s3, s2, 0x8
56 beq s3, zero, process_entry
57 and s2, s2, ~0x8
58 li s6, (1 << _PAGE_SHIFT) / SZREG
59
60copy_word:
61 /* copy page word by word */
62 REG_L s5, (s2)
63 REG_S s5, (s4)
64 PTR_ADDIU s4, s4, SZREG
65 PTR_ADDIU s2, s2, SZREG
66 LONG_ADDIU s6, s6, -1
67 beq s6, zero, process_entry
68 b copy_word
69 b process_entry
70
71done:
72#ifdef CONFIG_SMP
73 /* kexec_flag reset is signal to other CPUs what kernel
74 was moved to it's location. Note - we need relocated address
75 of kexec_flag. */
76
77 bal 1f
78 1: move t1,ra;
79 PTR_LA t2,1b
80 PTR_LA t0,kexec_flag
81 PTR_SUB t0,t0,t2;
82 PTR_ADD t0,t1,t0;
83 LONG_S zero,(t0)
84#endif
85
86#ifdef CONFIG_CPU_CAVIUM_OCTEON
87 /* We need to flush I-cache before jumping to new kernel.
88 * Unfortunately, this code is cpu-specific.
89 */
90 .set push
91 .set noreorder
92 syncw
93 syncw
94 synci 0($0)
95 .set pop
96#else
97 sync
98#endif
99 /* jump to kexec_start_address */
100 j s1
101 END(relocate_new_kernel)
102
103#ifdef CONFIG_SMP
104/*
105 * Other CPUs should wait until code is relocated and
106 * then start at entry (?) point.
107 */
108LEAF(kexec_smp_wait)
109 PTR_L a0, s_arg0
110 PTR_L a1, s_arg1
111 PTR_L a2, s_arg2
112 PTR_L a3, s_arg3
113 PTR_L s1, kexec_start_address
114
115 /* Non-relocated address works for args and kexec_start_address ( old
116 * kernel is not overwritten). But we need relocated address of
117 * kexec_flag.
118 */
119
120 bal 1f
1211: move t1,ra;
122 PTR_LA t2,1b
123 PTR_LA t0,kexec_flag
124 PTR_SUB t0,t0,t2;
125 PTR_ADD t0,t1,t0;
126
1271: LONG_L s0, (t0)
128 bne s0, zero,1b
129
130#ifdef USE_KEXEC_SMP_WAIT_FINAL
131 kexec_smp_wait_final
132#else
133 sync
134#endif
135 j s1
136 END(kexec_smp_wait)
137#endif
138
139#ifdef __mips64
140 /* all PTR's must be aligned to 8 byte in 64-bit mode */
141 .align 3
142#endif
143
144/* All parameters to new kernel are passed in registers a0-a3.
145 * kexec_args[0..3] are used to prepare register values.
146 */
147
148EXPORT(kexec_args)
149arg0: PTR_WD 0x0
150arg1: PTR_WD 0x0
151arg2: PTR_WD 0x0
152arg3: PTR_WD 0x0
153 .size kexec_args,PTRSIZE*4
154
155#ifdef CONFIG_SMP
156/*
157 * Secondary CPUs may have different kernel parameters in
158 * their registers a0-a3. secondary_kexec_args[0..3] are used
159 * to prepare register values.
160 */
161EXPORT(secondary_kexec_args)
162s_arg0: PTR_WD 0x0
163s_arg1: PTR_WD 0x0
164s_arg2: PTR_WD 0x0
165s_arg3: PTR_WD 0x0
166 .size secondary_kexec_args,PTRSIZE*4
167kexec_flag:
168 LONG 0x1
169
170#endif
171
172EXPORT(kexec_start_address)
173 PTR_WD 0x0
174 .size kexec_start_address, PTRSIZE
175
176EXPORT(kexec_indirection_page)
177 PTR_WD 0
178 .size kexec_indirection_page, PTRSIZE
179
180relocate_new_kernel_end:
181
182EXPORT(relocate_new_kernel_size)
183 PTR_WD relocate_new_kernel_end - relocate_new_kernel
184 .size relocate_new_kernel_size, PTRSIZE
185

source code of linux/arch/mips/kernel/relocate_kernel.S