mirror of https://gitee.com/openkylin/linux.git
253 lines
6.3 KiB
ArmAsm
253 lines
6.3 KiB
ArmAsm
|
/*
|
||
|
|
* linux/arch/unicore32/kernel/head.S
|
||
|
|
*
|
||
|
|
* Code specific to PKUnity SoC and UniCore ISA
|
||
|
|
*
|
||
|
|
* Copyright (C) 2001-2010 GUAN Xue-tao
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU General Public License version 2 as
|
||
|
|
* published by the Free Software Foundation.
|
||
|
|
*/
|
||
|
|
#include <linux/linkage.h>
|
||
|
|
#include <linux/init.h>
|
||
|
|
|
||
|
|
#include <asm/assembler.h>
|
||
|
|
#include <asm/ptrace.h>
|
||
|
|
#include <generated/asm-offsets.h>
|
||
|
|
#include <asm/memory.h>
|
||
|
|
#include <asm/thread_info.h>
|
||
|
|
#include <asm/system.h>
|
||
|
|
#include <asm/pgtable-hwdef.h>
|
||
|
|
|
||
|
|
#if (PHYS_OFFSET & 0x003fffff)
|
||
|
|
#error "PHYS_OFFSET must be at an even 4MiB boundary!"
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#define KERNEL_RAM_VADDR (PAGE_OFFSET + KERNEL_IMAGE_START)
|
||
|
|
#define KERNEL_RAM_PADDR (PHYS_OFFSET + KERNEL_IMAGE_START)
|
||
|
|
|
||
|
|
#define KERNEL_PGD_PADDR (KERNEL_RAM_PADDR - 0x1000)
|
||
|
|
#define KERNEL_PGD_VADDR (KERNEL_RAM_VADDR - 0x1000)
|
||
|
|
|
||
|
|
#define KERNEL_START KERNEL_RAM_VADDR
|
||
|
|
#define KERNEL_END _end
|
||
|
|
|
||
|
|
/*
|
||
|
|
* swapper_pg_dir is the virtual address of the initial page table.
|
||
|
|
* We place the page tables 4K below KERNEL_RAM_VADDR. Therefore, we must
|
||
|
|
* make sure that KERNEL_RAM_VADDR is correctly set. Currently, we expect
|
||
|
|
* the least significant 16 bits to be 0x8000, but we could probably
|
||
|
|
* relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x1000.
|
||
|
|
*/
|
||
|
|
#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
|
||
|
|
#error KERNEL_RAM_VADDR must start at 0xXXXX8000
|
||
|
|
#endif
|
||
|
|
|
||
|
|
.globl swapper_pg_dir
|
||
|
|
.equ swapper_pg_dir, KERNEL_RAM_VADDR - 0x1000
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Kernel startup entry point.
|
||
|
|
* ---------------------------
|
||
|
|
*
|
||
|
|
* This is normally called from the decompressor code. The requirements
|
||
|
|
* are: MMU = off, D-cache = off, I-cache = dont care
|
||
|
|
*
|
||
|
|
* This code is mostly position independent, so if you link the kernel at
|
||
|
|
* 0xc0008000, you call this at __pa(0xc0008000).
|
||
|
|
*/
|
||
|
|
__HEAD
|
||
|
|
ENTRY(stext)
|
||
|
|
@ set asr
|
||
|
|
mov r0, #PRIV_MODE @ ensure priv mode
|
||
|
|
or r0, #PSR_R_BIT | PSR_I_BIT @ disable irqs
|
||
|
|
mov.a asr, r0
|
||
|
|
|
||
|
|
@ process identify
|
||
|
|
movc r0, p0.c0, #0 @ cpuid
|
||
|
|
movl r1, 0xff00ffff @ mask
|
||
|
|
movl r2, 0x4d000863 @ value
|
||
|
|
and r0, r1, r0
|
||
|
|
cxor.a r0, r2
|
||
|
|
bne __error_p @ invalid processor id
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Clear the 4K level 1 swapper page table
|
||
|
|
*/
|
||
|
|
movl r0, #KERNEL_PGD_PADDR @ page table address
|
||
|
|
mov r1, #0
|
||
|
|
add r2, r0, #0x1000
|
||
|
|
101: stw.w r1, [r0]+, #4
|
||
|
|
stw.w r1, [r0]+, #4
|
||
|
|
stw.w r1, [r0]+, #4
|
||
|
|
stw.w r1, [r0]+, #4
|
||
|
|
cxor.a r0, r2
|
||
|
|
bne 101b
|
||
|
|
|
||
|
|
movl r4, #KERNEL_PGD_PADDR @ page table address
|
||
|
|
mov r7, #PMD_TYPE_SECT | PMD_PRESENT @ page size: section
|
||
|
|
or r7, r7, #PMD_SECT_CACHEABLE @ cacheable
|
||
|
|
or r7, r7, #PMD_SECT_READ | PMD_SECT_WRITE | PMD_SECT_EXEC
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Create identity mapping for first 4MB of kernel to
|
||
|
|
* cater for the MMU enable. This identity mapping
|
||
|
|
* will be removed by paging_init(). We use our current program
|
||
|
|
* counter to determine corresponding section base address.
|
||
|
|
*/
|
||
|
|
mov r6, pc
|
||
|
|
mov r6, r6 >> #22 @ start of kernel section
|
||
|
|
or r1, r7, r6 << #22 @ flags + kernel base
|
||
|
|
stw r1, [r4+], r6 << #2 @ identity mapping
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Now setup the pagetables for our kernel direct
|
||
|
|
* mapped region.
|
||
|
|
*/
|
||
|
|
add r0, r4, #(KERNEL_START & 0xff000000) >> 20
|
||
|
|
stw.w r1, [r0+], #(KERNEL_START & 0x00c00000) >> 20
|
||
|
|
movl r6, #(KERNEL_END - 1)
|
||
|
|
add r0, r0, #4
|
||
|
|
add r6, r4, r6 >> #20
|
||
|
|
102: csub.a r0, r6
|
||
|
|
add r1, r1, #1 << 22
|
||
|
|
bua 103f
|
||
|
|
stw.w r1, [r0]+, #4
|
||
|
|
b 102b
|
||
|
|
103:
|
||
|
|
/*
|
||
|
|
* Then map first 4MB of ram in case it contains our boot params.
|
||
|
|
*/
|
||
|
|
add r0, r4, #PAGE_OFFSET >> 20
|
||
|
|
or r6, r7, #(PHYS_OFFSET & 0xffc00000)
|
||
|
|
stw r6, [r0]
|
||
|
|
|
||
|
|
ldw r15, __switch_data @ address to jump to after
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Initialise TLB, Caches, and MMU state ready to switch the MMU
|
||
|
|
* on.
|
||
|
|
*/
|
||
|
|
mov r0, #0
|
||
|
|
movc p0.c5, r0, #28 @ cache invalidate all
|
||
|
|
nop8
|
||
|
|
movc p0.c6, r0, #6 @ TLB invalidate all
|
||
|
|
nop8
|
||
|
|
|
||
|
|
/*
|
||
|
|
* ..V. .... ..TB IDAM
|
||
|
|
* ..1. .... ..01 1111
|
||
|
|
*/
|
||
|
|
movl r0, #0x201f @ control register setting
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Setup common bits before finally enabling the MMU. Essentially
|
||
|
|
* this is just loading the page table pointer and domain access
|
||
|
|
* registers.
|
||
|
|
*/
|
||
|
|
#ifndef CONFIG_ALIGNMENT_TRAP
|
||
|
|
andn r0, r0, #CR_A
|
||
|
|
#endif
|
||
|
|
#ifdef CONFIG_CPU_DCACHE_DISABLE
|
||
|
|
andn r0, r0, #CR_D
|
||
|
|
#endif
|
||
|
|
#ifdef CONFIG_CPU_DCACHE_WRITETHROUGH
|
||
|
|
andn r0, r0, #CR_B
|
||
|
|
#endif
|
||
|
|
#ifdef CONFIG_CPU_ICACHE_DISABLE
|
||
|
|
andn r0, r0, #CR_I
|
||
|
|
#endif
|
||
|
|
|
||
|
|
movc p0.c2, r4, #0 @ set pgd
|
||
|
|
b __turn_mmu_on
|
||
|
|
ENDPROC(stext)
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Enable the MMU. This completely changes the stucture of the visible
|
||
|
|
* memory space. You will not be able to trace execution through this.
|
||
|
|
*
|
||
|
|
* r0 = cp#0 control register
|
||
|
|
* r15 = *virtual* address to jump to upon completion
|
||
|
|
*/
|
||
|
|
.align 5
|
||
|
|
__turn_mmu_on:
|
||
|
|
mov r0, r0
|
||
|
|
movc p0.c1, r0, #0 @ write control reg
|
||
|
|
nop @ fetch inst by phys addr
|
||
|
|
mov pc, r15
|
||
|
|
nop8 @ fetch inst by phys addr
|
||
|
|
ENDPROC(__turn_mmu_on)
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Setup the initial page tables. We only setup the barest
|
||
|
|
* amount which are required to get the kernel running, which
|
||
|
|
* generally means mapping in the kernel code.
|
||
|
|
*
|
||
|
|
* r9 = cpuid
|
||
|
|
* r10 = procinfo
|
||
|
|
*
|
||
|
|
* Returns:
|
||
|
|
* r0, r3, r6, r7 corrupted
|
||
|
|
* r4 = physical page table address
|
||
|
|
*/
|
||
|
|
.ltorg
|
||
|
|
|
||
|
|
.align 2
|
||
|
|
.type __switch_data, %object
|
||
|
|
__switch_data:
|
||
|
|
.long __mmap_switched
|
||
|
|
.long __bss_start @ r6
|
||
|
|
.long _end @ r7
|
||
|
|
.long cr_alignment @ r8
|
||
|
|
.long init_thread_union + THREAD_START_SP @ sp
|
||
|
|
|
||
|
|
/*
|
||
|
|
* The following fragment of code is executed with the MMU on in MMU mode,
|
||
|
|
* and uses absolute addresses; this is not position independent.
|
||
|
|
*
|
||
|
|
* r0 = cp#0 control register
|
||
|
|
*/
|
||
|
|
__mmap_switched:
|
||
|
|
adr r3, __switch_data + 4
|
||
|
|
|
||
|
|
ldm.w (r6, r7, r8), [r3]+
|
||
|
|
ldw sp, [r3]
|
||
|
|
|
||
|
|
mov fp, #0 @ Clear BSS (and zero fp)
|
||
|
|
203: csub.a r6, r7
|
||
|
|
bea 204f
|
||
|
|
stw.w fp, [r6]+,#4
|
||
|
|
b 203b
|
||
|
|
204:
|
||
|
|
andn r1, r0, #CR_A @ Clear 'A' bit
|
||
|
|
stm (r0, r1), [r8]+ @ Save control register values
|
||
|
|
b start_kernel
|
||
|
|
ENDPROC(__mmap_switched)
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Exception handling. Something went wrong and we can't proceed. We
|
||
|
|
* ought to tell the user, but since we don't have any guarantee that
|
||
|
|
* we're even running on the right architecture, we do virtually nothing.
|
||
|
|
*
|
||
|
|
* If CONFIG_DEBUG_LL is set we try to print out something about the error
|
||
|
|
* and hope for the best (useful if bootloader fails to pass a proper
|
||
|
|
* machine ID for example).
|
||
|
|
*/
|
||
|
|
__error_p:
|
||
|
|
#ifdef CONFIG_DEBUG_LL
|
||
|
|
adr r0, str_p1
|
||
|
|
b.l printascii
|
||
|
|
mov r0, r9
|
||
|
|
b.l printhex8
|
||
|
|
adr r0, str_p2
|
||
|
|
b.l printascii
|
||
|
|
901: nop8
|
||
|
|
b 901b
|
||
|
|
str_p1: .asciz "\nError: unrecognized processor variant (0x"
|
||
|
|
str_p2: .asciz ").\n"
|
||
|
|
.align
|
||
|
|
#endif
|
||
|
|
ENDPROC(__error_p)
|
||
|
|
|