| /* |
| * Copyright (C) 2012 Regents of the University of California |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation, version 2. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #include <asm/thread_info.h> |
| #include <asm/asm-offsets.h> |
| #include <asm/asm.h> |
| #include <linux/init.h> |
| #include <linux/linkage.h> |
| #include <asm/thread_info.h> |
| #include <asm/page.h> |
| #include <asm/csr.h> |
| |
| __INIT |
| ENTRY(_start) |
| /* Mask all interrupts */ |
| csrw sie, zero |
| |
| /* Load the global pointer */ |
| .option push |
| .option norelax |
| la gp, __global_pointer$ |
| .option pop |
| |
| /* |
| * Disable FPU to detect illegal usage of |
| * floating point in kernel space |
| */ |
| li t0, SR_FS |
| csrc sstatus, t0 |
| |
| /* Pick one hart to run the main boot sequence */ |
| la a3, hart_lottery |
| li a2, 1 |
| amoadd.w a3, a2, (a3) |
| bnez a3, .Lsecondary_start |
| |
| /* Save hart ID and DTB physical address */ |
| mv s0, a0 |
| mv s1, a1 |
| |
| /* Initialize page tables and relocate to virtual addresses */ |
| la sp, init_thread_union + THREAD_SIZE |
| call setup_vm |
| call relocate |
| |
| /* Restore C environment */ |
| la tp, init_task |
| sw s0, TASK_TI_CPU(tp) |
| |
| la sp, init_thread_union |
| li a0, ASM_THREAD_SIZE |
| add sp, sp, a0 |
| |
| /* Start the kernel */ |
| mv a0, s0 |
| mv a1, s1 |
| call parse_dtb |
| tail start_kernel |
| |
| relocate: |
| /* Relocate return address */ |
| li a1, PAGE_OFFSET |
| la a0, _start |
| sub a1, a1, a0 |
| add ra, ra, a1 |
| |
| /* Point stvec to virtual address of intruction after satp write */ |
| la a0, 1f |
| add a0, a0, a1 |
| csrw stvec, a0 |
| |
| /* Compute satp for kernel page tables, but don't load it yet */ |
| la a2, swapper_pg_dir |
| srl a2, a2, PAGE_SHIFT |
| li a1, SATP_MODE |
| or a2, a2, a1 |
| |
| /* |
| * Load trampoline page directory, which will cause us to trap to |
| * stvec if VA != PA, or simply fall through if VA == PA |
| */ |
| la a0, trampoline_pg_dir |
| srl a0, a0, PAGE_SHIFT |
| or a0, a0, a1 |
| sfence.vma |
| csrw sptbr, a0 |
| .align 2 |
| 1: |
| /* Set trap vector to spin forever to help debug */ |
| la a0, .Lsecondary_park |
| csrw stvec, a0 |
| |
| /* Reload the global pointer */ |
| .option push |
| .option norelax |
| la gp, __global_pointer$ |
| .option pop |
| |
| /* Switch to kernel page tables */ |
| csrw sptbr, a2 |
| |
| ret |
| |
| .Lsecondary_start: |
| #ifdef CONFIG_SMP |
| li a1, CONFIG_NR_CPUS |
| bgeu a0, a1, .Lsecondary_park |
| |
| /* Set trap vector to spin forever to help debug */ |
| la a3, .Lsecondary_park |
| csrw stvec, a3 |
| |
| slli a3, a0, LGREG |
| la a1, __cpu_up_stack_pointer |
| la a2, __cpu_up_task_pointer |
| add a1, a3, a1 |
| add a2, a3, a2 |
| |
| /* |
| * This hart didn't win the lottery, so we wait for the winning hart to |
| * get far enough along the boot process that it should continue. |
| */ |
| .Lwait_for_cpu_up: |
| /* FIXME: We should WFI to save some energy here. */ |
| REG_L sp, (a1) |
| REG_L tp, (a2) |
| beqz sp, .Lwait_for_cpu_up |
| beqz tp, .Lwait_for_cpu_up |
| fence |
| |
| /* Enable virtual memory and relocate to virtual address */ |
| call relocate |
| |
| tail smp_callin |
| #endif |
| |
| .align 2 |
| .Lsecondary_park: |
| /* We lack SMP support or have too many harts, so park this hart */ |
| wfi |
| j .Lsecondary_park |
| END(_start) |
| |
| __PAGE_ALIGNED_BSS |
| /* Empty zero page */ |
| .balign PAGE_SIZE |
