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| /*
| * 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
|
|
