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1/*
2 * Copyright (C) 2012 Regents of the University of California
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14#include <asm/thread_info.h>
15#include <asm/asm-offsets.h>
16#include <asm/asm.h>
17#include <linux/init.h>
18#include <linux/linkage.h>
19#include <asm/thread_info.h>
20#include <asm/page.h>
21#include <asm/csr.h>
22
23__INIT
24ENTRY(_start)
25 /* Mask all interrupts */
26 csrw sie, zero
27
28 /* Load the global pointer */
29.option push
30.option norelax
31 la gp, __global_pointer$
32.option pop
33
34 /*
35 * Disable FPU to detect illegal usage of
36 * floating point in kernel space
37 */
38 li t0, SR_FS
39 csrc sstatus, t0
40
41 /* Pick one hart to run the main boot sequence */
42 la a3, hart_lottery
43 li a2, 1
44 amoadd.w a3, a2, (a3)
45 bnez a3, .Lsecondary_start
46
47 /* Save hart ID and DTB physical address */
48 mv s0, a0
49 mv s1, a1
50
51 /* Initialize page tables and relocate to virtual addresses */
52 la sp, init_thread_union + THREAD_SIZE
53 call setup_vm
54 call relocate
55
56 /* Restore C environment */
57 la tp, init_task
58 sw s0, TASK_TI_CPU(tp)
59
60 la sp, init_thread_union
61 li a0, ASM_THREAD_SIZE
62 add sp, sp, a0
63
64 /* Start the kernel */
65 mv a0, s0
66 mv a1, s1
67 call parse_dtb
68 tail start_kernel
69
70relocate:
71 /* Relocate return address */
72 li a1, PAGE_OFFSET
73 la a0, _start
74 sub a1, a1, a0
75 add ra, ra, a1
76
77 /* Point stvec to virtual address of intruction after satp write */
78 la a0, 1f
79 add a0, a0, a1
80 csrw stvec, a0
81
82 /* Compute satp for kernel page tables, but don't load it yet */
83 la a2, swapper_pg_dir
84 srl a2, a2, PAGE_SHIFT
85 li a1, SATP_MODE
86 or a2, a2, a1
87
88 /*
89 * Load trampoline page directory, which will cause us to trap to
90 * stvec if VA != PA, or simply fall through if VA == PA
91 */
92 la a0, trampoline_pg_dir
93 srl a0, a0, PAGE_SHIFT
94 or a0, a0, a1
95 sfence.vma
96 csrw sptbr, a0
971:
98 /* Set trap vector to spin forever to help debug */
99 la a0, .Lsecondary_park
100 csrw stvec, a0
101
102 /* Reload the global pointer */
103.option push
104.option norelax
105 la gp, __global_pointer$
106.option pop
107
108 /* Switch to kernel page tables */
109 csrw sptbr, a2
110
111 ret
112
113.Lsecondary_start:
114#ifdef CONFIG_SMP
115 li a1, CONFIG_NR_CPUS
116 bgeu a0, a1, .Lsecondary_park
117
118 /* Set trap vector to spin forever to help debug */
119 la a3, .Lsecondary_park
120 csrw stvec, a3
121
122 slli a3, a0, LGREG
123 la a1, __cpu_up_stack_pointer
124 la a2, __cpu_up_task_pointer
125 add a1, a3, a1
126 add a2, a3, a2
127
128 /*
129 * This hart didn't win the lottery, so we wait for the winning hart to
130 * get far enough along the boot process that it should continue.
131 */
132.Lwait_for_cpu_up:
133 /* FIXME: We should WFI to save some energy here. */
134 REG_L sp, (a1)
135 REG_L tp, (a2)
136 beqz sp, .Lwait_for_cpu_up
137 beqz tp, .Lwait_for_cpu_up
138 fence
139
140 /* Enable virtual memory and relocate to virtual address */
141 call relocate
142
143 tail smp_callin
144#endif
145
146.Lsecondary_park:
147 /* We lack SMP support or have too many harts, so park this hart */
148 wfi
149 j .Lsecondary_park
150END(_start)
151
152__PAGE_ALIGNED_BSS
153 /* Empty zero page */
154 .balign PAGE_SIZE
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2012 Regents of the University of California
4 */
5
6#include <asm/asm-offsets.h>
7#include <asm/asm.h>
8#include <linux/init.h>
9#include <linux/linkage.h>
10#include <asm/thread_info.h>
11#include <asm/page.h>
12#include <asm/pgtable.h>
13#include <asm/csr.h>
14#include <asm/hwcap.h>
15#include <asm/image.h>
16#include <asm/scs.h>
17#include <asm/xip_fixup.h>
18#include "efi-header.S"
19
20__HEAD
21SYM_CODE_START(_start)
22 /*
23 * Image header expected by Linux boot-loaders. The image header data
24 * structure is described in asm/image.h.
25 * Do not modify it without modifying the structure and all bootloaders
26 * that expects this header format!!
27 */
28#ifdef CONFIG_EFI
29 /*
30 * This instruction decodes to "MZ" ASCII required by UEFI.
31 */
32 c.li s4,-13
33 j _start_kernel
34#else
35 /* jump to start kernel */
36 j _start_kernel
37 /* reserved */
38 .word 0
39#endif
40 .balign 8
41#ifdef CONFIG_RISCV_M_MODE
42 /* Image load offset (0MB) from start of RAM for M-mode */
43 .dword 0
44#else
45#if __riscv_xlen == 64
46 /* Image load offset(2MB) from start of RAM */
47 .dword 0x200000
48#else
49 /* Image load offset(4MB) from start of RAM */
50 .dword 0x400000
51#endif
52#endif
53 /* Effective size of kernel image */
54 .dword _end - _start
55 .dword __HEAD_FLAGS
56 .word RISCV_HEADER_VERSION
57 .word 0
58 .dword 0
59 .ascii RISCV_IMAGE_MAGIC
60 .balign 4
61 .ascii RISCV_IMAGE_MAGIC2
62#ifdef CONFIG_EFI
63 .word pe_head_start - _start
64pe_head_start:
65
66 __EFI_PE_HEADER
67#else
68 .word 0
69#endif
70
71.align 2
72#ifdef CONFIG_MMU
73 .global relocate_enable_mmu
74relocate_enable_mmu:
75 /* Relocate return address */
76 la a1, kernel_map
77 XIP_FIXUP_OFFSET a1
78 REG_L a1, KERNEL_MAP_VIRT_ADDR(a1)
79 la a2, _start
80 sub a1, a1, a2
81 add ra, ra, a1
82
83 /* Point stvec to virtual address of intruction after satp write */
84 la a2, 1f
85 add a2, a2, a1
86 csrw CSR_TVEC, a2
87
88 /* Compute satp for kernel page tables, but don't load it yet */
89 srl a2, a0, PAGE_SHIFT
90 la a1, satp_mode
91 XIP_FIXUP_OFFSET a1
92 REG_L a1, 0(a1)
93 or a2, a2, a1
94
95 /*
96 * Load trampoline page directory, which will cause us to trap to
97 * stvec if VA != PA, or simply fall through if VA == PA. We need a
98 * full fence here because setup_vm() just wrote these PTEs and we need
99 * to ensure the new translations are in use.
100 */
101 la a0, trampoline_pg_dir
102 XIP_FIXUP_OFFSET a0
103 srl a0, a0, PAGE_SHIFT
104 or a0, a0, a1
105 sfence.vma
106 csrw CSR_SATP, a0
107.align 2
1081:
109 /* Set trap vector to spin forever to help debug */
110 la a0, .Lsecondary_park
111 csrw CSR_TVEC, a0
112
113 /* Reload the global pointer */
114 load_global_pointer
115
116 /*
117 * Switch to kernel page tables. A full fence is necessary in order to
118 * avoid using the trampoline translations, which are only correct for
119 * the first superpage. Fetching the fence is guaranteed to work
120 * because that first superpage is translated the same way.
121 */
122 csrw CSR_SATP, a2
123 sfence.vma
124
125 ret
126#endif /* CONFIG_MMU */
127#ifdef CONFIG_SMP
128 .global secondary_start_sbi
129secondary_start_sbi:
130 /* Mask all interrupts */
131 csrw CSR_IE, zero
132 csrw CSR_IP, zero
133
134 /* Load the global pointer */
135 load_global_pointer
136
137 /*
138 * Disable FPU & VECTOR to detect illegal usage of
139 * floating point or vector in kernel space
140 */
141 li t0, SR_FS_VS
142 csrc CSR_STATUS, t0
143
144 /* Set trap vector to spin forever to help debug */
145 la a3, .Lsecondary_park
146 csrw CSR_TVEC, a3
147
148 /* a0 contains the hartid & a1 contains boot data */
149 li a2, SBI_HART_BOOT_TASK_PTR_OFFSET
150 XIP_FIXUP_OFFSET a2
151 add a2, a2, a1
152 REG_L tp, (a2)
153 li a3, SBI_HART_BOOT_STACK_PTR_OFFSET
154 XIP_FIXUP_OFFSET a3
155 add a3, a3, a1
156 REG_L sp, (a3)
157
158.Lsecondary_start_common:
159
160#ifdef CONFIG_MMU
161 /* Enable virtual memory and relocate to virtual address */
162 la a0, swapper_pg_dir
163 XIP_FIXUP_OFFSET a0
164 call relocate_enable_mmu
165#endif
166 call .Lsetup_trap_vector
167 scs_load_current
168 call smp_callin
169#endif /* CONFIG_SMP */
170
171.align 2
172.Lsecondary_park:
173 /*
174 * Park this hart if we:
175 * - have too many harts on CONFIG_RISCV_BOOT_SPINWAIT
176 * - receive an early trap, before setup_trap_vector finished
177 * - fail in smp_callin(), as a successful one wouldn't return
178 */
179 wfi
180 j .Lsecondary_park
181
182.align 2
183.Lsetup_trap_vector:
184 /* Set trap vector to exception handler */
185 la a0, handle_exception
186 csrw CSR_TVEC, a0
187
188 /*
189 * Set sup0 scratch register to 0, indicating to exception vector that
190 * we are presently executing in kernel.
191 */
192 csrw CSR_SCRATCH, zero
193 ret
194
195SYM_CODE_END(_start)
196
197SYM_CODE_START(_start_kernel)
198 /* Mask all interrupts */
199 csrw CSR_IE, zero
200 csrw CSR_IP, zero
201
202#ifdef CONFIG_RISCV_M_MODE
203 /* flush the instruction cache */
204 fence.i
205
206 /* Reset all registers except ra, a0, a1 */
207 call reset_regs
208
209 /*
210 * Setup a PMP to permit access to all of memory. Some machines may
211 * not implement PMPs, so we set up a quick trap handler to just skip
212 * touching the PMPs on any trap.
213 */
214 la a0, .Lpmp_done
215 csrw CSR_TVEC, a0
216
217 li a0, -1
218 csrw CSR_PMPADDR0, a0
219 li a0, (PMP_A_NAPOT | PMP_R | PMP_W | PMP_X)
220 csrw CSR_PMPCFG0, a0
221.align 2
222.Lpmp_done:
223
224 /*
225 * The hartid in a0 is expected later on, and we have no firmware
226 * to hand it to us.
227 */
228 csrr a0, CSR_MHARTID
229#endif /* CONFIG_RISCV_M_MODE */
230
231 /* Load the global pointer */
232 load_global_pointer
233
234 /*
235 * Disable FPU & VECTOR to detect illegal usage of
236 * floating point or vector in kernel space
237 */
238 li t0, SR_FS_VS
239 csrc CSR_STATUS, t0
240
241#ifdef CONFIG_RISCV_BOOT_SPINWAIT
242 li t0, CONFIG_NR_CPUS
243 blt a0, t0, .Lgood_cores
244 tail .Lsecondary_park
245.Lgood_cores:
246
247 /* The lottery system is only required for spinwait booting method */
248#ifndef CONFIG_XIP_KERNEL
249 /* Pick one hart to run the main boot sequence */
250 la a3, hart_lottery
251 li a2, 1
252 amoadd.w a3, a2, (a3)
253 bnez a3, .Lsecondary_start
254
255#else
256 /* hart_lottery in flash contains a magic number */
257 la a3, hart_lottery
258 mv a2, a3
259 XIP_FIXUP_OFFSET a2
260 XIP_FIXUP_FLASH_OFFSET a3
261 lw t1, (a3)
262 amoswap.w t0, t1, (a2)
263 /* first time here if hart_lottery in RAM is not set */
264 beq t0, t1, .Lsecondary_start
265
266#endif /* CONFIG_XIP */
267#endif /* CONFIG_RISCV_BOOT_SPINWAIT */
268
269#ifdef CONFIG_XIP_KERNEL
270 la sp, _end + THREAD_SIZE
271 XIP_FIXUP_OFFSET sp
272 mv s0, a0
273 mv s1, a1
274 call __copy_data
275
276 /* Restore a0 & a1 copy */
277 mv a0, s0
278 mv a1, s1
279#endif
280
281#ifndef CONFIG_XIP_KERNEL
282 /* Clear BSS for flat non-ELF images */
283 la a3, __bss_start
284 la a4, __bss_stop
285 ble a4, a3, .Lclear_bss_done
286.Lclear_bss:
287 REG_S zero, (a3)
288 add a3, a3, RISCV_SZPTR
289 blt a3, a4, .Lclear_bss
290.Lclear_bss_done:
291#endif
292 la a2, boot_cpu_hartid
293 XIP_FIXUP_OFFSET a2
294 REG_S a0, (a2)
295
296 /* Initialize page tables and relocate to virtual addresses */
297 la tp, init_task
298 la sp, init_thread_union + THREAD_SIZE
299 XIP_FIXUP_OFFSET sp
300 addi sp, sp, -PT_SIZE_ON_STACK
301 scs_load_init_stack
302#ifdef CONFIG_BUILTIN_DTB
303 la a0, __dtb_start
304 XIP_FIXUP_OFFSET a0
305#else
306 mv a0, a1
307#endif /* CONFIG_BUILTIN_DTB */
308 /* Set trap vector to spin forever to help debug */
309 la a3, .Lsecondary_park
310 csrw CSR_TVEC, a3
311 call setup_vm
312#ifdef CONFIG_MMU
313 la a0, early_pg_dir
314 XIP_FIXUP_OFFSET a0
315 call relocate_enable_mmu
316#endif /* CONFIG_MMU */
317
318 call .Lsetup_trap_vector
319 /* Restore C environment */
320 la tp, init_task
321 la sp, init_thread_union + THREAD_SIZE
322 addi sp, sp, -PT_SIZE_ON_STACK
323 scs_load_current
324
325#ifdef CONFIG_KASAN
326 call kasan_early_init
327#endif
328 /* Start the kernel */
329 call soc_early_init
330 tail start_kernel
331
332#ifdef CONFIG_RISCV_BOOT_SPINWAIT
333.Lsecondary_start:
334 /* Set trap vector to spin forever to help debug */
335 la a3, .Lsecondary_park
336 csrw CSR_TVEC, a3
337
338 slli a3, a0, LGREG
339 la a1, __cpu_spinwait_stack_pointer
340 XIP_FIXUP_OFFSET a1
341 la a2, __cpu_spinwait_task_pointer
342 XIP_FIXUP_OFFSET a2
343 add a1, a3, a1
344 add a2, a3, a2
345
346 /*
347 * This hart didn't win the lottery, so we wait for the winning hart to
348 * get far enough along the boot process that it should continue.
349 */
350.Lwait_for_cpu_up:
351 /* FIXME: We should WFI to save some energy here. */
352 REG_L sp, (a1)
353 REG_L tp, (a2)
354 beqz sp, .Lwait_for_cpu_up
355 beqz tp, .Lwait_for_cpu_up
356 fence
357
358 tail .Lsecondary_start_common
359#endif /* CONFIG_RISCV_BOOT_SPINWAIT */
360
361SYM_CODE_END(_start_kernel)
362
363#ifdef CONFIG_RISCV_M_MODE
364SYM_CODE_START_LOCAL(reset_regs)
365 li sp, 0
366 li gp, 0
367 li tp, 0
368 li t0, 0
369 li t1, 0
370 li t2, 0
371 li s0, 0
372 li s1, 0
373 li a2, 0
374 li a3, 0
375 li a4, 0
376 li a5, 0
377 li a6, 0
378 li a7, 0
379 li s2, 0
380 li s3, 0
381 li s4, 0
382 li s5, 0
383 li s6, 0
384 li s7, 0
385 li s8, 0
386 li s9, 0
387 li s10, 0
388 li s11, 0
389 li t3, 0
390 li t4, 0
391 li t5, 0
392 li t6, 0
393 csrw CSR_SCRATCH, 0
394
395#ifdef CONFIG_FPU
396 csrr t0, CSR_MISA
397 andi t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)
398 beqz t0, .Lreset_regs_done_fpu
399
400 li t1, SR_FS
401 csrs CSR_STATUS, t1
402 fmv.s.x f0, zero
403 fmv.s.x f1, zero
404 fmv.s.x f2, zero
405 fmv.s.x f3, zero
406 fmv.s.x f4, zero
407 fmv.s.x f5, zero
408 fmv.s.x f6, zero
409 fmv.s.x f7, zero
410 fmv.s.x f8, zero
411 fmv.s.x f9, zero
412 fmv.s.x f10, zero
413 fmv.s.x f11, zero
414 fmv.s.x f12, zero
415 fmv.s.x f13, zero
416 fmv.s.x f14, zero
417 fmv.s.x f15, zero
418 fmv.s.x f16, zero
419 fmv.s.x f17, zero
420 fmv.s.x f18, zero
421 fmv.s.x f19, zero
422 fmv.s.x f20, zero
423 fmv.s.x f21, zero
424 fmv.s.x f22, zero
425 fmv.s.x f23, zero
426 fmv.s.x f24, zero
427 fmv.s.x f25, zero
428 fmv.s.x f26, zero
429 fmv.s.x f27, zero
430 fmv.s.x f28, zero
431 fmv.s.x f29, zero
432 fmv.s.x f30, zero
433 fmv.s.x f31, zero
434 csrw fcsr, 0
435 /* note that the caller must clear SR_FS */
436.Lreset_regs_done_fpu:
437#endif /* CONFIG_FPU */
438
439#ifdef CONFIG_RISCV_ISA_V
440 csrr t0, CSR_MISA
441 li t1, COMPAT_HWCAP_ISA_V
442 and t0, t0, t1
443 beqz t0, .Lreset_regs_done_vector
444
445 /*
446 * Clear vector registers and reset vcsr
447 * VLMAX has a defined value, VLEN is a constant,
448 * and this form of vsetvli is defined to set vl to VLMAX.
449 */
450 li t1, SR_VS
451 csrs CSR_STATUS, t1
452 csrs CSR_VCSR, x0
453 vsetvli t1, x0, e8, m8, ta, ma
454 vmv.v.i v0, 0
455 vmv.v.i v8, 0
456 vmv.v.i v16, 0
457 vmv.v.i v24, 0
458 /* note that the caller must clear SR_VS */
459.Lreset_regs_done_vector:
460#endif /* CONFIG_RISCV_ISA_V */
461 ret
462SYM_CODE_END(reset_regs)
463#endif /* CONFIG_RISCV_M_MODE */