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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/kernel/head.S
downloadconfigs-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * linux/arch/arm/kernel/head.S
+ *
+ * Copyright (C) 1994-2002 Russell King
+ *
+ * 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/config.h>
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+#include <asm/assembler.h>
+#include <asm/domain.h>
+#include <asm/mach-types.h>
+#include <asm/procinfo.h>
+#include <asm/ptrace.h>
+#include <asm/constants.h>
+#include <asm/system.h>
+
+#define PROCINFO_MMUFLAGS 8
+#define PROCINFO_INITFUNC 12
+
+#define MACHINFO_TYPE 0
+#define MACHINFO_PHYSRAM 4
+#define MACHINFO_PHYSIO 8
+#define MACHINFO_PGOFFIO 12
+#define MACHINFO_NAME 16
+
+#ifndef CONFIG_XIP_KERNEL
+/*
+ * We place the page tables 16K below TEXTADDR. Therefore, we must make sure
+ * that TEXTADDR is correctly set. Currently, we expect the least significant
+ * 16 bits to be 0x8000, but we could probably relax this restriction to
+ * TEXTADDR >= PAGE_OFFSET + 0x4000
+ *
+ * Note that swapper_pg_dir is the virtual address of the page tables, and
+ * pgtbl gives us a position-independent reference to these tables. We can
+ * do this because stext == TEXTADDR
+ */
+#if (TEXTADDR & 0xffff) != 0x8000
+#error TEXTADDR must start at 0xXXXX8000
+#endif
+
+ .globl swapper_pg_dir
+ .equ swapper_pg_dir, TEXTADDR - 0x4000
+
+ .macro pgtbl, rd, phys
+ adr \rd, stext
+ sub \rd, \rd, #0x4000
+ .endm
+#else
+/*
+ * XIP Kernel:
+ *
+ * We place the page tables 16K below DATAADDR. Therefore, we must make sure
+ * that DATAADDR is correctly set. Currently, we expect the least significant
+ * 16 bits to be 0x8000, but we could probably relax this restriction to
+ * DATAADDR >= PAGE_OFFSET + 0x4000
+ *
+ * Note that pgtbl is meant to return the physical address of swapper_pg_dir.
+ * We can't make it relative to the kernel position in this case since
+ * the kernel can physically be anywhere.
+ */
+#if (DATAADDR & 0xffff) != 0x8000
+#error DATAADDR must start at 0xXXXX8000
+#endif
+
+ .globl swapper_pg_dir
+ .equ swapper_pg_dir, DATAADDR - 0x4000
+
+ .macro pgtbl, rd, phys
+ ldr \rd, =((DATAADDR - 0x4000) - VIRT_OFFSET)
+ add \rd, \rd, \phys
+ .endm
+#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.
+ *
+ * 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.
+ */
+ __INIT
+ .type stext, %function
+ENTRY(stext)
+ msr cpsr_c, #PSR_F_BIT | PSR_I_BIT | MODE_SVC @ ensure svc mode
+ @ and irqs disabled
+ bl __lookup_processor_type @ r5=procinfo r9=cpuid
+ movs r10, r5 @ invalid processor (r5=0)?
+ beq __error_p @ yes, error 'p'
+ bl __lookup_machine_type @ r5=machinfo
+ movs r8, r5 @ invalid machine (r5=0)?
+ beq __error_a @ yes, error 'a'
+ 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_machine_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, __switch_data @ address to jump to after
+ @ mmu has been enabled
+ adr lr, __enable_mmu @ return (PIC) address
+ add pc, r10, #PROCINFO_INITFUNC
+
+ .type __switch_data, %object
+__switch_data:
+ .long __mmap_switched
+ .long __data_loc @ r4
+ .long __data_start @ r5
+ .long __bss_start @ r6
+ .long _end @ r7
+ .long processor_id @ r4
+ .long __machine_arch_type @ r5
+ .long cr_alignment @ r6
+ .long init_thread_union+8192 @ sp
+
+/*
+ * The following fragment of code is executed with the MMU on, and uses
+ * absolute addresses; this is not position independent.
+ *
+ * r0 = cp#15 control register
+ * r1 = machine ID
+ * r9 = processor ID
+ */
+ .type __mmap_switched, %function
+__mmap_switched:
+ adr r3, __switch_data + 4
+
+ ldmia r3!, {r4, r5, r6, r7}
+ cmp r4, r5 @ Copy data segment if needed
+1: cmpne r5, r6
+ ldrne fp, [r4], #4
+ strne fp, [r5], #4
+ bne 1b
+
+ mov fp, #0 @ Clear BSS (and zero fp)
+1: cmp r6, r7
+ strcc fp, [r6],#4
+ bcc 1b
+
+ ldmia r3, {r4, r5, r6, sp}
+ str r9, [r4] @ Save processor ID
+ str r1, [r5] @ Save machine type
+ bic r4, r0, #CR_A @ Clear 'A' bit
+ stmia r6, {r0, r4} @ Save control register values
+ b start_kernel
+
+
+
+/*
+ * Setup common bits before finally enabling the MMU. Essentially
+ * this is just loading the page table pointer and domain access
+ * registers.
+ */
+ .type __enable_mmu, %function
+__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
+
+/*
+ * 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
+ * r13 = *virtual* address to jump to upon completion
+ *
+ * other registers depend on the function called upon completion
+ */
+ .align 5
+ .type __turn_mmu_on, %function
+__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, r3
+ mov pc, r13
+
+
+
+/*
+ * 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 = machinfo
+ * r9 = cpuid
+ * r10 = procinfo
+ *
+ * Returns:
+ * r0, r3, r5, r6, r7 corrupted
+ * r4 = physical page table address
+ */
+ .type __create_page_tables, %function
+__create_page_tables:
+ ldr r5, [r8, #MACHINFO_PHYSRAM] @ physram
+ pgtbl r4, r5 @ 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_MMUFLAGS] @ mmuflags
+
+ /*
+ * Create identity mapping for first MB 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, lsr #20 @ start of kernel section
+ orr r3, r7, r6, lsl #20 @ flags + kernel base
+ str r3, [r4, r6, lsl #2] @ identity mapping
+
+ /*
+ * Now setup the pagetables for our kernel direct
+ * mapped region. We round TEXTADDR down to the
+ * nearest megabyte boundary. It is assumed that
+ * the kernel fits within 4 contigous 1MB sections.
+ */
+ add r0, r4, #(TEXTADDR & 0xff000000) >> 18 @ start of kernel
+ str r3, [r0, #(TEXTADDR & 0x00f00000) >> 18]!
+ add r3, r3, #1 << 20
+ str r3, [r0, #4]! @ KERNEL + 1MB
+ add r3, r3, #1 << 20
+ str r3, [r0, #4]! @ KERNEL + 2MB
+ add r3, r3, #1 << 20
+ str r3, [r0, #4] @ KERNEL + 3MB
+
+ /*
+ * Then map first 1MB of ram in case it contains our boot params.
+ */
+ add r0, r4, #VIRT_OFFSET >> 18
+ orr r6, r5, r7
+ str r6, [r0]
+
+#ifdef CONFIG_XIP_KERNEL
+ /*
+ * Map some ram to cover our .data and .bss areas.
+ * Mapping 3MB should be plenty.
+ */
+ sub r3, r4, r5
+ mov r3, r3, lsr #20
+ add r0, r0, r3, lsl #2
+ add r6, r6, r3, lsl #20
+ str r6, [r0], #4
+ add r6, r6, #(1 << 20)
+ str r6, [r0], #4
+ add r6, r6, #(1 << 20)
+ str r6, [r0]
+#endif
+
+ bic r7, r7, #0x0c @ turn off cacheable
+ @ and bufferable bits
+#ifdef CONFIG_DEBUG_LL
+ /*
+ * Map in IO space for serial debugging.
+ * This allows debug messages to be output
+ * via a serial console before paging_init.
+ */
+ ldr r3, [r8, #MACHINFO_PGOFFIO]
+ 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
+ ldr r3, [r8, #MACHINFO_PHYSIO]
+ orr r3, r3, r7
+1: str r3, [r0], #4
+ add r3, r3, #1 << 20
+ teq r0, r6
+ bne 1b
+#if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
+ /*
+ * If we're using the NetWinder, we need to map in
+ * the 16550-type serial port for the debug messages
+ */
+ teq r1, #MACH_TYPE_NETWINDER
+ teqne r1, #MACH_TYPE_CATS
+ bne 1f
+ add r0, r4, #0x3fc0 @ ff000000
+ mov r3, #0x7c000000
+ orr r3, r3, r7
+ str r3, [r0], #4
+ add r3, r3, #1 << 20
+ str r3, [r0], #4
+1:
+#endif
+#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, #0x80 @ 02000000
+ mov r3, #0x02000000
+ orr r3, r3, r7
+ str r3, [r0]
+ add r0, r4, #0x3600 @ d8000000
+ str r3, [r0]
+#endif
+ mov pc, lr
+ .ltorg
+
+
+
+/*
+ * 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).
+ */
+
+ .type __error_p, %function
+__error_p:
+#ifdef CONFIG_DEBUG_LL
+ adr r0, str_p1
+ bl printascii
+ b __error
+str_p1: .asciz "\nError: unrecognized/unsupported processor variant.\n"
+ .align
+#endif
+
+ .type __error_a, %function
+__error_a:
+#ifdef CONFIG_DEBUG_LL
+ mov r4, r1 @ preserve machine ID
+ adr r0, str_a1
+ bl printascii
+ mov r0, r4
+ bl printhex8
+ adr r0, str_a2
+ bl printascii
+ adr r3, 3f
+ ldmia r3, {r4, r5, r6} @ get machine desc list
+ sub r4, r3, r4 @ get offset between virt&phys
+ add r5, r5, r4 @ convert virt addresses to
+ add r6, r6, r4 @ physical address space
+1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type
+ bl printhex8
+ mov r0, #'\t'
+ bl printch
+ ldr r0, [r5, #MACHINFO_NAME] @ get machine name
+ add r0, r0, r4
+ bl printascii
+ mov r0, #'\n'
+ bl printch
+ add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
+ cmp r5, r6
+ blo 1b
+ adr r0, str_a3
+ bl printascii
+ b __error
+str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x"
+str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
+str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n"
+ .align
+#endif
+
+ .type __error, %function
+__error:
+#ifdef CONFIG_ARCH_RPC
+/*
+ * Turn the screen red on a error - RiscPC only.
+ */
+ mov r0, #0x02000000
+ mov r3, #0x11
+ orr r3, r3, r3, lsl #8
+ orr r3, r3, r3, lsl #16
+ str r3, [r0], #4
+ str r3, [r0], #4
+ str r3, [r0], #4
+ str r3, [r0], #4
+#endif
+1: mov r0, r0
+ b 1b
+
+
+/*
+ * Read processor ID register (CP#15, CR0), and look up in the linker-built
+ * supported processor list. Note that we can't use the absolute addresses
+ * for the __proc_info lists since we aren't running with the MMU on
+ * (and therefore, we are not in the correct address space). We have to
+ * calculate the offset.
+ *
+ * Returns:
+ * r3, r4, r6 corrupted
+ * r5 = proc_info pointer in physical address space
+ * r9 = cpuid
+ */
+ .type __lookup_processor_type, %function
+__lookup_processor_type:
+ adr r3, 3f
+ ldmda r3, {r5, r6, r9}
+ sub r3, r3, r9 @ get offset between virt&phys
+ add r5, r5, r3 @ convert virt addresses to
+ add r6, r6, r3 @ physical address space
+ mrc p15, 0, r9, c0, c0 @ get processor id
+1: ldmia r5, {r3, r4} @ value, mask
+ and r4, r4, r9 @ mask wanted bits
+ teq r3, r4
+ beq 2f
+ add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
+ cmp r5, r6
+ blo 1b
+ mov r5, #0 @ unknown processor
+2: mov pc, lr
+
+/*
+ * This provides a C-API version of the above function.
+ */
+ENTRY(lookup_processor_type)
+ stmfd sp!, {r4 - r6, r9, lr}
+ bl __lookup_processor_type
+ mov r0, r5
+ ldmfd sp!, {r4 - r6, r9, pc}
+
+/*
+ * Look in include/asm-arm/procinfo.h and arch/arm/kernel/arch.[ch] for
+ * more information about the __proc_info and __arch_info structures.
+ */
+ .long __proc_info_begin
+ .long __proc_info_end
+3: .long .
+ .long __arch_info_begin
+ .long __arch_info_end
+
+/*
+ * Lookup machine architecture in the linker-build list of architectures.
+ * Note that we can't use the absolute addresses for the __arch_info
+ * lists since we aren't running with the MMU on (and therefore, we are
+ * not in the correct address space). We have to calculate the offset.
+ *
+ * r1 = machine architecture number
+ * Returns:
+ * r3, r4, r6 corrupted
+ * r5 = mach_info pointer in physical address space
+ */
+ .type __lookup_machine_type, %function
+__lookup_machine_type:
+ adr r3, 3b
+ ldmia r3, {r4, r5, r6}
+ sub r3, r3, r4 @ get offset between virt&phys
+ add r5, r5, r3 @ convert virt addresses to
+ add r6, r6, r3 @ physical address space
+1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type
+ teq r3, r1 @ matches loader number?
+ beq 2f @ found
+ add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
+ cmp r5, r6
+ blo 1b
+ mov r5, #0 @ unknown machine
+2: mov pc, lr
+
+/*
+ * This provides a C-API version of the above function.
+ */
+ENTRY(lookup_machine_type)
+ stmfd sp!, {r4 - r6, lr}
+ mov r1, r0
+ bl __lookup_machine_type
+ mov r0, r5
+ ldmfd sp!, {r4 - r6, pc}