/* * 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 #include #include #include #include #include #include #include #include #ifdef CONFIG_DEBUG_LL #include #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 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, * 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 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 r4, r4, r5 @ mmu has been enabled ldr r4, [r7, r4] @ get secondary_data.pgdir 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 pointer * r4 = page table pointer * r9 = processor ID * r13 = *virtual* address to jump to upon completion */ __enable_mmu: #ifdef CONFIG_ALIGNMENT_TRAP 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 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"