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 "efi-header.S" 17 18#ifdef CONFIG_XIP_KERNEL 19.macro XIP_FIXUP_OFFSET reg 20 REG_L t0, _xip_fixup 21 add \reg, \reg, t0 22.endm 23_xip_fixup: .dword CONFIG_PHYS_RAM_BASE - CONFIG_XIP_PHYS_ADDR - XIP_OFFSET 24#else 25.macro XIP_FIXUP_OFFSET reg 26.endm 27#endif /* CONFIG_XIP_KERNEL */ 28 29__HEAD 30ENTRY(_start) 31 /* 32 * Image header expected by Linux boot-loaders. The image header data 33 * structure is described in asm/image.h. 34 * Do not modify it without modifying the structure and all bootloaders 35 * that expects this header format!! 36 */ 37#ifdef CONFIG_EFI 38 /* 39 * This instruction decodes to "MZ" ASCII required by UEFI. 40 */ 41 c.li s4,-13 42 j _start_kernel 43#else 44 /* jump to start kernel */ 45 j _start_kernel 46 /* reserved */ 47 .word 0 48#endif 49 .balign 8 50#ifdef CONFIG_RISCV_M_MODE 51 /* Image load offset (0MB) from start of RAM for M-mode */ 52 .dword 0 53#else 54#if __riscv_xlen == 64 55 /* Image load offset(2MB) from start of RAM */ 56 .dword 0x200000 57#else 58 /* Image load offset(4MB) from start of RAM */ 59 .dword 0x400000 60#endif 61#endif 62 /* Effective size of kernel image */ 63 .dword _end - _start 64 .dword __HEAD_FLAGS 65 .word RISCV_HEADER_VERSION 66 .word 0 67 .dword 0 68 .ascii RISCV_IMAGE_MAGIC 69 .balign 4 70 .ascii RISCV_IMAGE_MAGIC2 71#ifdef CONFIG_EFI 72 .word pe_head_start - _start 73pe_head_start: 74 75 __EFI_PE_HEADER 76#else 77 .word 0 78#endif 79 80.align 2 81#ifdef CONFIG_MMU 82relocate: 83 /* Relocate return address */ 84 la a1, kernel_virt_addr 85 XIP_FIXUP_OFFSET a1 86 REG_L a1, 0(a1) 87 la a2, _start 88 sub a1, a1, a2 89 add ra, ra, a1 90 91 /* Point stvec to virtual address of intruction after satp write */ 92 la a2, 1f 93 add a2, a2, a1 94 csrw CSR_TVEC, a2 95 96 /* Compute satp for kernel page tables, but don't load it yet */ 97 srl a2, a0, PAGE_SHIFT 98 li a1, SATP_MODE 99 or a2, a2, a1 100 101 /* 102 * Load trampoline page directory, which will cause us to trap to 103 * stvec if VA != PA, or simply fall through if VA == PA. We need a 104 * full fence here because setup_vm() just wrote these PTEs and we need 105 * to ensure the new translations are in use. 106 */ 107 la a0, trampoline_pg_dir 108 XIP_FIXUP_OFFSET a0 109 srl a0, a0, PAGE_SHIFT 110 or a0, a0, a1 111 sfence.vma 112 csrw CSR_SATP, a0 113.align 2 1141: 115 /* Set trap vector to spin forever to help debug */ 116 la a0, .Lsecondary_park 117 csrw CSR_TVEC, a0 118 119 /* Reload the global pointer */ 120.option push 121.option norelax 122 la gp, __global_pointer$ 123.option pop 124 125 /* 126 * Switch to kernel page tables. A full fence is necessary in order to 127 * avoid using the trampoline translations, which are only correct for 128 * the first superpage. Fetching the fence is guarnteed to work 129 * because that first superpage is translated the same way. 130 */ 131 csrw CSR_SATP, a2 132 sfence.vma 133 134 ret 135#endif /* CONFIG_MMU */ 136#ifdef CONFIG_SMP 137 .global secondary_start_sbi 138secondary_start_sbi: 139 /* Mask all interrupts */ 140 csrw CSR_IE, zero 141 csrw CSR_IP, zero 142 143 /* Load the global pointer */ 144 .option push 145 .option norelax 146 la gp, __global_pointer$ 147 .option pop 148 149 /* 150 * Disable FPU to detect illegal usage of 151 * floating point in kernel space 152 */ 153 li t0, SR_FS 154 csrc CSR_STATUS, t0 155 156 /* Set trap vector to spin forever to help debug */ 157 la a3, .Lsecondary_park 158 csrw CSR_TVEC, a3 159 160 slli a3, a0, LGREG 161 la a4, __cpu_up_stack_pointer 162 XIP_FIXUP_OFFSET a4 163 la a5, __cpu_up_task_pointer 164 XIP_FIXUP_OFFSET a5 165 add a4, a3, a4 166 add a5, a3, a5 167 REG_L sp, (a4) 168 REG_L tp, (a5) 169 170 .global secondary_start_common 171secondary_start_common: 172 173#ifdef CONFIG_MMU 174 /* Enable virtual memory and relocate to virtual address */ 175 la a0, swapper_pg_dir 176 XIP_FIXUP_OFFSET a0 177 call relocate 178#endif 179 call setup_trap_vector 180 tail smp_callin 181#endif /* CONFIG_SMP */ 182 183.align 2 184setup_trap_vector: 185 /* Set trap vector to exception handler */ 186 la a0, handle_exception 187 csrw CSR_TVEC, a0 188 189 /* 190 * Set sup0 scratch register to 0, indicating to exception vector that 191 * we are presently executing in kernel. 192 */ 193 csrw CSR_SCRATCH, zero 194 ret 195 196.Lsecondary_park: 197 /* We lack SMP support or have too many harts, so park this hart */ 198 wfi 199 j .Lsecondary_park 200 201END(_start) 202 203ENTRY(_start_kernel) 204 /* Mask all interrupts */ 205 csrw CSR_IE, zero 206 csrw CSR_IP, zero 207 208#ifdef CONFIG_RISCV_M_MODE 209 /* flush the instruction cache */ 210 fence.i 211 212 /* Reset all registers except ra, a0, a1 */ 213 call reset_regs 214 215 /* 216 * Setup a PMP to permit access to all of memory. Some machines may 217 * not implement PMPs, so we set up a quick trap handler to just skip 218 * touching the PMPs on any trap. 219 */ 220 la a0, pmp_done 221 csrw CSR_TVEC, a0 222 223 li a0, -1 224 csrw CSR_PMPADDR0, a0 225 li a0, (PMP_A_NAPOT | PMP_R | PMP_W | PMP_X) 226 csrw CSR_PMPCFG0, a0 227.align 2 228pmp_done: 229 230 /* 231 * The hartid in a0 is expected later on, and we have no firmware 232 * to hand it to us. 233 */ 234 csrr a0, CSR_MHARTID 235#endif /* CONFIG_RISCV_M_MODE */ 236 237 /* Load the global pointer */ 238.option push 239.option norelax 240 la gp, __global_pointer$ 241.option pop 242 243 /* 244 * Disable FPU to detect illegal usage of 245 * floating point in kernel space 246 */ 247 li t0, SR_FS 248 csrc CSR_STATUS, t0 249 250#ifdef CONFIG_SMP 251 li t0, CONFIG_NR_CPUS 252 blt a0, t0, .Lgood_cores 253 tail .Lsecondary_park 254.Lgood_cores: 255#endif 256 257#ifndef CONFIG_XIP_KERNEL 258 /* Pick one hart to run the main boot sequence */ 259 la a3, hart_lottery 260 li a2, 1 261 amoadd.w a3, a2, (a3) 262 bnez a3, .Lsecondary_start 263 264#else 265 /* hart_lottery in flash contains a magic number */ 266 la a3, hart_lottery 267 mv a2, a3 268 XIP_FIXUP_OFFSET a2 269 lw t1, (a3) 270 amoswap.w t0, t1, (a2) 271 /* first time here if hart_lottery in RAM is not set */ 272 beq t0, t1, .Lsecondary_start 273 274 la sp, _end + THREAD_SIZE 275 XIP_FIXUP_OFFSET sp 276 mv s0, a0 277 call __copy_data 278 279 /* Restore a0 copy */ 280 mv a0, s0 281#endif 282 283#ifndef CONFIG_XIP_KERNEL 284 /* Clear BSS for flat non-ELF images */ 285 la a3, __bss_start 286 la a4, __bss_stop 287 ble a4, a3, clear_bss_done 288clear_bss: 289 REG_S zero, (a3) 290 add a3, a3, RISCV_SZPTR 291 blt a3, a4, clear_bss 292clear_bss_done: 293#endif 294 /* Save hart ID and DTB physical address */ 295 mv s0, a0 296 mv s1, a1 297 298 la a2, boot_cpu_hartid 299 XIP_FIXUP_OFFSET a2 300 REG_S a0, (a2) 301 302 /* Initialize page tables and relocate to virtual addresses */ 303 la sp, init_thread_union + THREAD_SIZE 304 XIP_FIXUP_OFFSET sp 305#ifdef CONFIG_BUILTIN_DTB 306 la a0, __dtb_start 307#else 308 mv a0, s1 309#endif /* CONFIG_BUILTIN_DTB */ 310 call setup_vm 311#ifdef CONFIG_MMU 312 la a0, early_pg_dir 313 XIP_FIXUP_OFFSET a0 314 call relocate 315#endif /* CONFIG_MMU */ 316 317 call setup_trap_vector 318 /* Restore C environment */ 319 la tp, init_task 320 sw zero, TASK_TI_CPU(tp) 321 la sp, init_thread_union + THREAD_SIZE 322 323#ifdef CONFIG_KASAN 324 call kasan_early_init 325#endif 326 /* Start the kernel */ 327 call soc_early_init 328 tail start_kernel 329 330.Lsecondary_start: 331#ifdef CONFIG_SMP 332 /* Set trap vector to spin forever to help debug */ 333 la a3, .Lsecondary_park 334 csrw CSR_TVEC, a3 335 336 slli a3, a0, LGREG 337 la a1, __cpu_up_stack_pointer 338 XIP_FIXUP_OFFSET a1 339 la a2, __cpu_up_task_pointer 340 XIP_FIXUP_OFFSET a2 341 add a1, a3, a1 342 add a2, a3, a2 343 344 /* 345 * This hart didn't win the lottery, so we wait for the winning hart to 346 * get far enough along the boot process that it should continue. 347 */ 348.Lwait_for_cpu_up: 349 /* FIXME: We should WFI to save some energy here. */ 350 REG_L sp, (a1) 351 REG_L tp, (a2) 352 beqz sp, .Lwait_for_cpu_up 353 beqz tp, .Lwait_for_cpu_up 354 fence 355 356 tail secondary_start_common 357#endif 358 359END(_start_kernel) 360 361#ifdef CONFIG_RISCV_M_MODE 362ENTRY(reset_regs) 363 li sp, 0 364 li gp, 0 365 li tp, 0 366 li t0, 0 367 li t1, 0 368 li t2, 0 369 li s0, 0 370 li s1, 0 371 li a2, 0 372 li a3, 0 373 li a4, 0 374 li a5, 0 375 li a6, 0 376 li a7, 0 377 li s2, 0 378 li s3, 0 379 li s4, 0 380 li s5, 0 381 li s6, 0 382 li s7, 0 383 li s8, 0 384 li s9, 0 385 li s10, 0 386 li s11, 0 387 li t3, 0 388 li t4, 0 389 li t5, 0 390 li t6, 0 391 csrw CSR_SCRATCH, 0 392 393#ifdef CONFIG_FPU 394 csrr t0, CSR_MISA 395 andi t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D) 396 beqz t0, .Lreset_regs_done 397 398 li t1, SR_FS 399 csrs CSR_STATUS, t1 400 fmv.s.x f0, zero 401 fmv.s.x f1, zero 402 fmv.s.x f2, zero 403 fmv.s.x f3, zero 404 fmv.s.x f4, zero 405 fmv.s.x f5, zero 406 fmv.s.x f6, zero 407 fmv.s.x f7, zero 408 fmv.s.x f8, zero 409 fmv.s.x f9, zero 410 fmv.s.x f10, zero 411 fmv.s.x f11, zero 412 fmv.s.x f12, zero 413 fmv.s.x f13, zero 414 fmv.s.x f14, zero 415 fmv.s.x f15, zero 416 fmv.s.x f16, zero 417 fmv.s.x f17, zero 418 fmv.s.x f18, zero 419 fmv.s.x f19, zero 420 fmv.s.x f20, zero 421 fmv.s.x f21, zero 422 fmv.s.x f22, zero 423 fmv.s.x f23, zero 424 fmv.s.x f24, zero 425 fmv.s.x f25, zero 426 fmv.s.x f26, zero 427 fmv.s.x f27, zero 428 fmv.s.x f28, zero 429 fmv.s.x f29, zero 430 fmv.s.x f30, zero 431 fmv.s.x f31, zero 432 csrw fcsr, 0 433 /* note that the caller must clear SR_FS */ 434#endif /* CONFIG_FPU */ 435.Lreset_regs_done: 436 ret 437END(reset_regs) 438#endif /* CONFIG_RISCV_M_MODE */ 439 440__PAGE_ALIGNED_BSS 441 /* Empty zero page */ 442 .balign PAGE_SIZE 443