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Diffstat (limited to 'arch/arm/kernel/head.S')
| -rw-r--r-- | arch/arm/kernel/head.S | 592 |
1 files changed, 592 insertions, 0 deletions
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S new file mode 100644 index 00000000..673151c7 --- /dev/null +++ b/arch/arm/kernel/head.S @@ -0,0 +1,592 @@ +/* + * linux/arch/arm/kernel/head.S + * + * Copyright (C) 1994-2002 Russell King + * Copyright (c) 2003 ARM Limited + * All Rights Reserved + * + * 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. + * + * Kernel startup code for all 32-bit CPUs + */ +#include <linux/linkage.h> +#include <linux/init.h> + +#include <asm/assembler.h> +#include <asm/domain.h> +#include <asm/ptrace.h> +#include <asm/asm-offsets.h> +#include <asm/memory.h> +#include <asm/thread_info.h> +#include <asm/system.h> + +#ifdef CONFIG_DEBUG_LL +#include <mach/debug-macro.S> +#endif + +/* + * swapper_pg_dir is the virtual address of the initial page table. + * We place the page tables 16K 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 + 0x4000. + */ +#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET) +#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 - 0x4000 + + .macro pgtbl, rd, phys + add \rd, \phys, #TEXT_OFFSET - 0x4000 + .endm + +#ifdef CONFIG_XIP_KERNEL +#define KERNEL_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) +#define KERNEL_END _edata_loc +#else +#define KERNEL_START KERNEL_RAM_VADDR +#define KERNEL_END _end +#endif + +/* + * Kernel startup entry point. + * --------------------------- + * + * This is normally called from the decompressor code. The requirements + * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0, + * r1 = machine nr, r2 = atags or dtb pointer. + * + * This code is mostly position independent, so if you link the kernel at + * 0xc0008000, you call this at __pa(0xc0008000). + * + * See linux/arch/arm/tools/mach-types for the complete list of machine + * numbers for r1. + * + * We're trying to keep crap to a minimum; DO NOT add any machine specific + * crap here - that's what the boot loader (or in extreme, well justified + * circumstances, zImage) is for. + */ + __HEAD +ENTRY(stext) + setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode + @ and irqs disabled + mrc p15, 0, r9, c0, c0 @ get processor id + bl __lookup_processor_type @ r5=procinfo r9=cpuid + movs r10, r5 @ invalid processor (r5=0)? + THUMB( it eq ) @ force fixup-able long branch encoding + beq __error_p @ yes, error 'p' + +#ifndef CONFIG_XIP_KERNEL + adr r3, 2f + ldmia r3, {r4, r8} + sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET) + add r8, r8, r4 @ PHYS_OFFSET +#else + ldr r8, =PLAT_PHYS_OFFSET +#endif + + /* + * r1 = machine no, r2 = atags or dtb, + * r8 = phys_offset, r9 = cpuid, r10 = procinfo + */ + bl __vet_atags +#ifdef CONFIG_SMP_ON_UP + bl __fixup_smp +#endif +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT + bl __fixup_pv_table +#endif + bl __create_page_tables + + /* + * The following calls CPU specific code in a position independent + * manner. See arch/arm/mm/proc-*.S for details. r10 = base of + * xxx_proc_info structure selected by __lookup_processor_type + * above. On return, the CPU will be ready for the MMU to be + * turned on, and r0 will hold the CPU control register value. + */ + ldr r13, =__mmap_switched @ address to jump to after + @ mmu has been enabled + adr lr, BSYM(1f) @ return (PIC) address + mov r8, r4 @ set TTBR1 to swapper_pg_dir + ARM( add pc, r10, #PROCINFO_INITFUNC ) + THUMB( add r12, r10, #PROCINFO_INITFUNC ) + THUMB( mov pc, r12 ) +1: b __enable_mmu +ENDPROC(stext) + .ltorg +#ifndef CONFIG_XIP_KERNEL +2: .long . + .long PAGE_OFFSET +#endif + +/* + * 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. + * + * r8 = phys_offset, r9 = cpuid, r10 = procinfo + * + * Returns: + * r0, r3, r5-r7 corrupted + * r4 = physical page table address + */ +__create_page_tables: + pgtbl r4, r8 @ page table address + + /* + * Clear the 16K level 1 swapper page table + */ + mov r0, r4 + mov r3, #0 + add r6, r0, #0x4000 +1: str r3, [r0], #4 + str r3, [r0], #4 + str r3, [r0], #4 + str r3, [r0], #4 + teq r0, r6 + bne 1b + + ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags + + /* + * Create identity mapping to cater for __enable_mmu. + * This identity mapping will be removed by paging_init(). + */ + adr r0, __enable_mmu_loc + ldmia r0, {r3, r5, r6} + sub r0, r0, r3 @ virt->phys offset + add r5, r5, r0 @ phys __enable_mmu + add r6, r6, r0 @ phys __enable_mmu_end + mov r5, r5, lsr #20 + mov r6, r6, lsr #20 + +1: orr r3, r7, r5, lsl #20 @ flags + kernel base + str r3, [r4, r5, lsl #2] @ identity mapping + teq r5, r6 + addne r5, r5, #1 @ next section + bne 1b + + /* + * Now setup the pagetables for our kernel direct + * mapped region. + */ + mov r3, pc + mov r3, r3, lsr #20 + orr r3, r7, r3, lsl #20 + add r0, r4, #(KERNEL_START & 0xff000000) >> 18 + str r3, [r0, #(KERNEL_START & 0x00f00000) >> 18]! + ldr r6, =(KERNEL_END - 1) + add r0, r0, #4 + add r6, r4, r6, lsr #18 +1: cmp r0, r6 + add r3, r3, #1 << 20 + strls r3, [r0], #4 + bls 1b + +#ifdef CONFIG_XIP_KERNEL + /* + * Map some ram to cover our .data and .bss areas. + */ + add r3, r8, #TEXT_OFFSET + orr r3, r3, r7 + add r0, r4, #(KERNEL_RAM_VADDR & 0xff000000) >> 18 + str r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> 18]! + ldr r6, =(_end - 1) + add r0, r0, #4 + add r6, r4, r6, lsr #18 +1: cmp r0, r6 + add r3, r3, #1 << 20 + strls r3, [r0], #4 + bls 1b +#endif + + /* + * Then map boot params address in r2 or + * the first 1MB of ram if boot params address is not specified. + */ + mov r0, r2, lsr #20 + movs r0, r0, lsl #20 + moveq r0, r8 + sub r3, r0, r8 + add r3, r3, #PAGE_OFFSET + add r3, r4, r3, lsr #18 + orr r6, r7, r0 + str r6, [r3] + +#ifdef CONFIG_DEBUG_LL +#ifndef CONFIG_DEBUG_ICEDCC + /* + * Map in IO space for serial debugging. + * This allows debug messages to be output + * via a serial console before paging_init. + */ + addruart r7, r3 + + mov r3, r3, lsr #20 + mov r3, r3, lsl #2 + + add r0, r4, r3 + rsb r3, r3, #0x4000 @ PTRS_PER_PGD*sizeof(long) + cmp r3, #0x0800 @ limit to 512MB + movhi r3, #0x0800 + add r6, r0, r3 + mov r3, r7, lsr #20 + ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags + orr r3, r7, r3, lsl #20 +1: str r3, [r0], #4 + add r3, r3, #1 << 20 + teq r0, r6 + bne 1b + +#else /* CONFIG_DEBUG_ICEDCC */ + /* we don't need any serial debugging mappings for ICEDCC */ + ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags +#endif /* !CONFIG_DEBUG_ICEDCC */ + +#if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS) + /* + * If we're using the NetWinder or CATS, we also need to map + * in the 16550-type serial port for the debug messages + */ + add r0, r4, #0xff000000 >> 18 + orr r3, r7, #0x7c000000 + str r3, [r0] +#endif +#ifdef CONFIG_ARCH_RPC + /* + * Map in screen at 0x02000000 & SCREEN2_BASE + * Similar reasons here - for debug. This is + * only for Acorn RiscPC architectures. + */ + add r0, r4, #0x02000000 >> 18 + orr r3, r7, #0x02000000 + str r3, [r0] + add r0, r4, #0xd8000000 >> 18 + str r3, [r0] +#endif +#endif + mov pc, lr +ENDPROC(__create_page_tables) + .ltorg + .align +__enable_mmu_loc: + .long . + .long __enable_mmu + .long __enable_mmu_end + +#if defined(CONFIG_SMP) + __CPUINIT +ENTRY(secondary_startup) + /* + * Common entry point for secondary CPUs. + * + * Ensure that we're in SVC mode, and IRQs are disabled. Lookup + * the processor type - there is no need to check the machine type + * as it has already been validated by the primary processor. + */ + setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 + mrc p15, 0, r9, c0, c0 @ get processor id + bl __lookup_processor_type + movs r10, r5 @ invalid processor? + moveq r0, #'p' @ yes, error 'p' + THUMB( it eq ) @ force fixup-able long branch encoding + beq __error_p + + /* + * Use the page tables supplied from __cpu_up. + */ + adr r4, __secondary_data + ldmia r4, {r5, r7, r12} @ address to jump to after + sub lr, r4, r5 @ mmu has been enabled + ldr r4, [r7, lr] @ get secondary_data.pgdir + add r7, r7, #4 + ldr r8, [r7, lr] @ get secondary_data.swapper_pg_dir + adr lr, BSYM(__enable_mmu) @ return address + mov r13, r12 @ __secondary_switched address + ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor + @ (return control reg) + THUMB( add r12, r10, #PROCINFO_INITFUNC ) + THUMB( mov pc, r12 ) +ENDPROC(secondary_startup) + + /* + * r6 = &secondary_data + */ +ENTRY(__secondary_switched) + ldr sp, [r7, #4] @ get secondary_data.stack + mov fp, #0 + b secondary_start_kernel +ENDPROC(__secondary_switched) + + .align + + .type __secondary_data, %object +__secondary_data: + .long . + .long secondary_data + .long __secondary_switched +#endif /* defined(CONFIG_SMP) */ + + + +/* + * Setup common bits before finally enabling the MMU. Essentially + * this is just loading the page table pointer and domain access + * registers. + * + * r0 = cp#15 control register + * r1 = machine ID + * r2 = atags or dtb pointer + * r4 = page table pointer + * r9 = processor ID + * r13 = *virtual* address to jump to upon completion + */ +__enable_mmu: +#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6 + orr r0, r0, #CR_A +#else + bic r0, r0, #CR_A +#endif +#ifdef CONFIG_CPU_DCACHE_DISABLE + bic r0, r0, #CR_C +#endif +#ifdef CONFIG_CPU_BPREDICT_DISABLE + bic r0, r0, #CR_Z +#endif +#ifdef CONFIG_CPU_ICACHE_DISABLE + bic r0, r0, #CR_I +#endif + mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \ + domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \ + domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \ + domain_val(DOMAIN_IO, DOMAIN_CLIENT)) + mcr p15, 0, r5, c3, c0, 0 @ load domain access register + mcr p15, 0, r4, c2, c0, 0 @ load page table pointer + b __turn_mmu_on +ENDPROC(__enable_mmu) + +/* + * Enable the MMU. This completely changes the structure of the visible + * memory space. You will not be able to trace execution through this. + * If you have an enquiry about this, *please* check the linux-arm-kernel + * mailing list archives BEFORE sending another post to the list. + * + * r0 = cp#15 control register + * r1 = machine ID + * r2 = atags or dtb pointer + * r9 = processor ID + * r13 = *virtual* address to jump to upon completion + * + * other registers depend on the function called upon completion + */ + .align 5 +__turn_mmu_on: + mov r0, r0 + mcr p15, 0, r0, c1, c0, 0 @ write control reg + mrc p15, 0, r3, c0, c0, 0 @ read id reg + mov r3, r3 + mov r3, r13 + mov pc, r3 +__enable_mmu_end: +ENDPROC(__turn_mmu_on) + + +#ifdef CONFIG_SMP_ON_UP + __INIT +__fixup_smp: + and r3, r9, #0x000f0000 @ architecture version + teq r3, #0x000f0000 @ CPU ID supported? + bne __fixup_smp_on_up @ no, assume UP + + bic r3, r9, #0x00ff0000 + bic r3, r3, #0x0000000f @ mask 0xff00fff0 + mov r4, #0x41000000 + orr r4, r4, #0x0000b000 + orr r4, r4, #0x00000020 @ val 0x4100b020 + teq r3, r4 @ ARM 11MPCore? + moveq pc, lr @ yes, assume SMP + + mrc p15, 0, r0, c0, c0, 5 @ read MPIDR + and r0, r0, #0xc0000000 @ multiprocessing extensions and + teq r0, #0x80000000 @ not part of a uniprocessor system? + moveq pc, lr @ yes, assume SMP + +__fixup_smp_on_up: + adr r0, 1f + ldmia r0, {r3 - r5} + sub r3, r0, r3 + add r4, r4, r3 + add r5, r5, r3 + b __do_fixup_smp_on_up +ENDPROC(__fixup_smp) + + .align +1: .word . + .word __smpalt_begin + .word __smpalt_end + + .pushsection .data + .globl smp_on_up +smp_on_up: + ALT_SMP(.long 1) + ALT_UP(.long 0) + .popsection +#endif + + .text +__do_fixup_smp_on_up: + cmp r4, r5 + movhs pc, lr + ldmia r4!, {r0, r6} + ARM( str r6, [r0, r3] ) + THUMB( add r0, r0, r3 ) +#ifdef __ARMEB__ + THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian. +#endif + THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords + THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3. + THUMB( strh r6, [r0] ) + b __do_fixup_smp_on_up +ENDPROC(__do_fixup_smp_on_up) + +ENTRY(fixup_smp) + stmfd sp!, {r4 - r6, lr} + mov r4, r0 + add r5, r0, r1 + mov r3, #0 + bl __do_fixup_smp_on_up + ldmfd sp!, {r4 - r6, pc} +ENDPROC(fixup_smp) + +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT + +/* __fixup_pv_table - patch the stub instructions with the delta between + * PHYS_OFFSET and PAGE_OFFSET, which is assumed to be 16MiB aligned and + * can be expressed by an immediate shifter operand. The stub instruction + * has a form of '(add|sub) rd, rn, #imm'. + */ + __HEAD +__fixup_pv_table: + adr r0, 1f + ldmia r0, {r3-r5, r7} + sub r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET + add r4, r4, r3 @ adjust table start address + add r5, r5, r3 @ adjust table end address + add r7, r7, r3 @ adjust __pv_phys_offset address + str r8, [r7] @ save computed PHYS_OFFSET to __pv_phys_offset +#ifndef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT + mov r6, r3, lsr #24 @ constant for add/sub instructions + teq r3, r6, lsl #24 @ must be 16MiB aligned +#else + mov r6, r3, lsr #16 @ constant for add/sub instructions + teq r3, r6, lsl #16 @ must be 64kiB aligned +#endif +THUMB( it ne @ cross section branch ) + bne __error + str r6, [r7, #4] @ save to __pv_offset + b __fixup_a_pv_table +ENDPROC(__fixup_pv_table) + + .align +1: .long . + .long __pv_table_begin + .long __pv_table_end +2: .long __pv_phys_offset + + .text +__fixup_a_pv_table: +#ifdef CONFIG_THUMB2_KERNEL +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT + lsls r0, r6, #24 + lsr r6, #8 + beq 1f + clz r7, r0 + lsr r0, #24 + lsl r0, r7 + bic r0, 0x0080 + lsrs r7, #1 + orrcs r0, #0x0080 + orr r0, r0, r7, lsl #12 +#endif +1: lsls r6, #24 + beq 4f + clz r7, r6 + lsr r6, #24 + lsl r6, r7 + bic r6, #0x0080 + lsrs r7, #1 + orrcs r6, #0x0080 + orr r6, r6, r7, lsl #12 + orr r6, #0x4000 + b 4f +2: @ at this point the C flag is always clear + add r7, r3 +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT + ldrh ip, [r7] + tst ip, 0x0400 @ the i bit tells us LS or MS byte + beq 3f + cmp r0, #0 @ set C flag, and ... + biceq ip, 0x0400 @ immediate zero value has a special encoding + streqh ip, [r7] @ that requires the i bit cleared +#endif +3: ldrh ip, [r7, #2] + and ip, 0x8f00 + orrcc ip, r6 @ mask in offset bits 31-24 + orrcs ip, r0 @ mask in offset bits 23-16 + strh ip, [r7, #2] +4: cmp r4, r5 + ldrcc r7, [r4], #4 @ use branch for delay slot + bcc 2b + bx lr +#else +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT + and r0, r6, #255 @ offset bits 23-16 + mov r6, r6, lsr #8 @ offset bits 31-24 +#else + mov r0, #0 @ just in case... +#endif + b 3f +2: ldr ip, [r7, r3] + bic ip, ip, #0x000000ff + tst ip, #0x400 @ rotate shift tells us LS or MS byte + orrne ip, ip, r6 @ mask in offset bits 31-24 + orreq ip, ip, r0 @ mask in offset bits 23-16 + str ip, [r7, r3] +3: cmp r4, r5 + ldrcc r7, [r4], #4 @ use branch for delay slot + bcc 2b + mov pc, lr +#endif +ENDPROC(__fixup_a_pv_table) + +ENTRY(fixup_pv_table) + stmfd sp!, {r4 - r7, lr} + ldr r2, 2f @ get address of __pv_phys_offset + mov r3, #0 @ no offset + mov r4, r0 @ r0 = table start + add r5, r0, r1 @ r1 = table size + ldr r6, [r2, #4] @ get __pv_offset + bl __fixup_a_pv_table + ldmfd sp!, {r4 - r7, pc} +ENDPROC(fixup_pv_table) + + .align +2: .long __pv_phys_offset + + .data + .globl __pv_phys_offset + .type __pv_phys_offset, %object +__pv_phys_offset: + .long 0 + .size __pv_phys_offset, . - __pv_phys_offset +__pv_offset: + .long 0 +#endif + +#include "head-common.S" |