1/* 2 * linux/arch/arm/kernel/head-nommu.S 3 * 4 * Copyright (C) 1994-2002 Russell King 5 * Copyright (C) 2003-2006 Hyok S. Choi 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * Common kernel startup code (non-paged MM) 12 * 13 */ 14#include <linux/linkage.h> 15#include <linux/init.h> 16 17#include <asm/assembler.h> 18#include <asm/ptrace.h> 19#include <asm/asm-offsets.h> 20#include <asm/memory.h> 21#include <asm/cp15.h> 22#include <asm/thread_info.h> 23#include <asm/v7m.h> 24#include <asm/mpu.h> 25#include <asm/page.h> 26 27/* 28 * Kernel startup entry point. 29 * --------------------------- 30 * 31 * This is normally called from the decompressor code. The requirements 32 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0, 33 * r1 = machine nr. 34 * 35 * See linux/arch/arm/tools/mach-types for the complete list of machine 36 * numbers for r1. 37 * 38 */ 39 40 __HEAD 41 42#ifdef CONFIG_CPU_THUMBONLY 43 .thumb 44ENTRY(stext) 45#else 46 .arm 47ENTRY(stext) 48 49 THUMB( badr r9, 1f ) @ Kernel is always entered in ARM. 50 THUMB( bx r9 ) @ If this is a Thumb-2 kernel, 51 THUMB( .thumb ) @ switch to Thumb now. 52 THUMB(1: ) 53#endif 54 55 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode 56 @ and irqs disabled 57#if defined(CONFIG_CPU_CP15) 58 mrc p15, 0, r9, c0, c0 @ get processor id 59#elif defined(CONFIG_CPU_V7M) 60 ldr r9, =BASEADDR_V7M_SCB 61 ldr r9, [r9, V7M_SCB_CPUID] 62#else 63 ldr r9, =CONFIG_PROCESSOR_ID 64#endif 65 bl __lookup_processor_type @ r5=procinfo r9=cpuid 66 movs r10, r5 @ invalid processor (r5=0)? 67 beq __error_p @ yes, error 'p' 68 69#ifdef CONFIG_ARM_MPU 70 /* Calculate the size of a region covering just the kernel */ 71 ldr r5, =PLAT_PHYS_OFFSET @ Region start: PHYS_OFFSET 72 ldr r6, =(_end) @ Cover whole kernel 73 sub r6, r6, r5 @ Minimum size of region to map 74 clz r6, r6 @ Region size must be 2^N... 75 rsb r6, r6, #31 @ ...so round up region size 76 lsl r6, r6, #MPU_RSR_SZ @ Put size in right field 77 orr r6, r6, #(1 << MPU_RSR_EN) @ Set region enabled bit 78 bl __setup_mpu 79#endif 80 81 badr lr, 1f @ return (PIC) address 82 ldr r12, [r10, #PROCINFO_INITFUNC] 83 add r12, r12, r10 84 ret r12 851: bl __after_proc_init 86 b __mmap_switched 87ENDPROC(stext) 88 89#ifdef CONFIG_SMP 90 .text 91ENTRY(secondary_startup) 92 /* 93 * Common entry point for secondary CPUs. 94 * 95 * Ensure that we're in SVC mode, and IRQs are disabled. Lookup 96 * the processor type - there is no need to check the machine type 97 * as it has already been validated by the primary processor. 98 */ 99 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 100#ifndef CONFIG_CPU_CP15 101 ldr r9, =CONFIG_PROCESSOR_ID 102#else 103 mrc p15, 0, r9, c0, c0 @ get processor id 104#endif 105 bl __lookup_processor_type @ r5=procinfo r9=cpuid 106 movs r10, r5 @ invalid processor? 107 beq __error_p @ yes, error 'p' 108 109 ldr r7, __secondary_data 110 111#ifdef CONFIG_ARM_MPU 112 /* Use MPU region info supplied by __cpu_up */ 113 ldr r6, [r7] @ get secondary_data.mpu_szr 114 bl __setup_mpu @ Initialize the MPU 115#endif 116 117 badr lr, 1f @ return (PIC) address 118 ldr r12, [r10, #PROCINFO_INITFUNC] 119 add r12, r12, r10 120 ret r12 1211: bl __after_proc_init 122 ldr sp, [r7, #12] @ set up the stack pointer 123 mov fp, #0 124 b secondary_start_kernel 125ENDPROC(secondary_startup) 126 127 .type __secondary_data, %object 128__secondary_data: 129 .long secondary_data 130#endif /* CONFIG_SMP */ 131 132/* 133 * Set the Control Register and Read the process ID. 134 */ 135__after_proc_init: 136#ifdef CONFIG_CPU_CP15 137 /* 138 * CP15 system control register value returned in r0 from 139 * the CPU init function. 140 */ 141#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6 142 orr r0, r0, #CR_A 143#else 144 bic r0, r0, #CR_A 145#endif 146#ifdef CONFIG_CPU_DCACHE_DISABLE 147 bic r0, r0, #CR_C 148#endif 149#ifdef CONFIG_CPU_BPREDICT_DISABLE 150 bic r0, r0, #CR_Z 151#endif 152#ifdef CONFIG_CPU_ICACHE_DISABLE 153 bic r0, r0, #CR_I 154#endif 155 mcr p15, 0, r0, c1, c0, 0 @ write control reg 156#elif defined (CONFIG_CPU_V7M) 157 /* For V7M systems we want to modify the CCR similarly to the SCTLR */ 158#ifdef CONFIG_CPU_DCACHE_DISABLE 159 bic r0, r0, #V7M_SCB_CCR_DC 160#endif 161#ifdef CONFIG_CPU_BPREDICT_DISABLE 162 bic r0, r0, #V7M_SCB_CCR_BP 163#endif 164#ifdef CONFIG_CPU_ICACHE_DISABLE 165 bic r0, r0, #V7M_SCB_CCR_IC 166#endif 167 movw r3, #:lower16:(BASEADDR_V7M_SCB + V7M_SCB_CCR) 168 movt r3, #:upper16:(BASEADDR_V7M_SCB + V7M_SCB_CCR) 169 str r0, [r3] 170#endif /* CONFIG_CPU_CP15 elif CONFIG_CPU_V7M */ 171 ret lr 172ENDPROC(__after_proc_init) 173 .ltorg 174 175#ifdef CONFIG_ARM_MPU 176 177 178/* Set which MPU region should be programmed */ 179.macro set_region_nr tmp, rgnr 180 mov \tmp, \rgnr @ Use static region numbers 181 mcr p15, 0, \tmp, c6, c2, 0 @ Write RGNR 182.endm 183 184/* Setup a single MPU region, either D or I side (D-side for unified) */ 185.macro setup_region bar, acr, sr, side = MPU_DATA_SIDE 186 mcr p15, 0, \bar, c6, c1, (0 + \side) @ I/DRBAR 187 mcr p15, 0, \acr, c6, c1, (4 + \side) @ I/DRACR 188 mcr p15, 0, \sr, c6, c1, (2 + \side) @ I/DRSR 189.endm 190 191/* 192 * Setup the MPU and initial MPU Regions. We create the following regions: 193 * Region 0: Use this for probing the MPU details, so leave disabled. 194 * Region 1: Background region - covers the whole of RAM as strongly ordered 195 * Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6 196 * Region 3: Normal, shared, inaccessible from PL0 to protect the vectors page 197 * 198 * r6: Value to be written to DRSR (and IRSR if required) for MPU_RAM_REGION 199*/ 200 201ENTRY(__setup_mpu) 202 203 /* Probe for v7 PMSA compliance */ 204 mrc p15, 0, r0, c0, c1, 4 @ Read ID_MMFR0 205 and r0, r0, #(MMFR0_PMSA) @ PMSA field 206 teq r0, #(MMFR0_PMSAv7) @ PMSA v7 207 bne __error_p @ Fail: ARM_MPU on NOT v7 PMSA 208 209 /* Determine whether the D/I-side memory map is unified. We set the 210 * flags here and continue to use them for the rest of this function */ 211 mrc p15, 0, r0, c0, c0, 4 @ MPUIR 212 ands r5, r0, #MPUIR_DREGION_SZMASK @ 0 size d region => No MPU 213 beq __error_p @ Fail: ARM_MPU and no MPU 214 tst r0, #MPUIR_nU @ MPUIR_nU = 0 for unified 215 216 /* Setup second region first to free up r6 */ 217 set_region_nr r0, #MPU_RAM_REGION 218 isb 219 /* Full access from PL0, PL1, shared for CONFIG_SMP, cacheable */ 220 ldr r0, =PLAT_PHYS_OFFSET @ RAM starts at PHYS_OFFSET 221 ldr r5,=(MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL) 222 223 setup_region r0, r5, r6, MPU_DATA_SIDE @ PHYS_OFFSET, shared, enabled 224 beq 1f @ Memory-map not unified 225 setup_region r0, r5, r6, MPU_INSTR_SIDE @ PHYS_OFFSET, shared, enabled 2261: isb 227 228 /* First/background region */ 229 set_region_nr r0, #MPU_BG_REGION 230 isb 231 /* Execute Never, strongly ordered, inaccessible to PL0, rw PL1 */ 232 mov r0, #0 @ BG region starts at 0x0 233 ldr r5,=(MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA) 234 mov r6, #MPU_RSR_ALL_MEM @ 4GB region, enabled 235 236 setup_region r0, r5, r6, MPU_DATA_SIDE @ 0x0, BG region, enabled 237 beq 2f @ Memory-map not unified 238 setup_region r0, r5, r6, MPU_INSTR_SIDE @ 0x0, BG region, enabled 2392: isb 240 241 /* Vectors region */ 242 set_region_nr r0, #MPU_VECTORS_REGION 243 isb 244 /* Shared, inaccessible to PL0, rw PL1 */ 245 mov r0, #CONFIG_VECTORS_BASE @ Cover from VECTORS_BASE 246 ldr r5,=(MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL) 247 /* Writing N to bits 5:1 (RSR_SZ) --> region size 2^N+1 */ 248 mov r6, #(((2 * PAGE_SHIFT - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN) 249 250 setup_region r0, r5, r6, MPU_DATA_SIDE @ VECTORS_BASE, PL0 NA, enabled 251 beq 3f @ Memory-map not unified 252 setup_region r0, r5, r6, MPU_INSTR_SIDE @ VECTORS_BASE, PL0 NA, enabled 2533: isb 254 255 /* Enable the MPU */ 256 mrc p15, 0, r0, c1, c0, 0 @ Read SCTLR 257 bic r0, r0, #CR_BR @ Disable the 'default mem-map' 258 orr r0, r0, #CR_M @ Set SCTRL.M (MPU on) 259 mcr p15, 0, r0, c1, c0, 0 @ Enable MPU 260 isb 261 ret lr 262ENDPROC(__setup_mpu) 263#endif 264#include "head-common.S" 265