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linux/arch/arm/kernel/head.S
Ben Dooks 97bcb0fea5 ARM: set BE8 if LE in head code 
If we are booting in LE and compiled for BE8, then add code to
set the state to bE8. Since the instruction stream is always LE,
we do not need to do anything special to the instruction.

Also ensure that the secondary processors are started in the same mode.

Note, we do add about 20 bytes to the kernel image, but it seems easier
to do this than adding another configuration to change.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
2013-10-19 20:46:33 +01:00

642 lines
16 KiB
ArmAsm
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/*
* 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/cp15.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/pgtable.h>
#if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_SEMIHOSTING)
#include 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
#ifdef CONFIG_ARM_LPAE
/* LPAE requires an additional page for the PGD */
#define PG_DIR_SIZE 0x5000
#define PMD_ORDER 3
#else
#define PG_DIR_SIZE 0x4000
#define PMD_ORDER 2
#endif
.globl swapper_pg_dir
.equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
.macro pgtbl, rd, phys
add \rd, \phys, #TEXT_OFFSET - PG_DIR_SIZE
.endm
/*
* 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.
*/
.arm
__HEAD
ENTRY(stext)
ARM_BE8(setend be ) @ ensure we are in BE8 mode
THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM.
THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
THUMB( .thumb ) @ switch to Thumb now.
THUMB(1: )
#ifdef CONFIG_ARM_VIRT_EXT
bl __hyp_stub_install
#endif
@ ensure svc mode and all interrupts masked
safe_svcmode_maskall r9
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'
#ifdef CONFIG_ARM_LPAE
mrc p15, 0, r3, c0, c1, 4 @ read ID_MMFR0
and r3, r3, #0xf @ extract VMSA support
cmp r3, #5 @ long-descriptor translation table format?
THUMB( it lo ) @ force fixup-able long branch encoding
blo __error_p @ only classic page table format
#endif
#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, =PHYS_OFFSET @ always constant in this case
#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 = page table (see ARCH_PGD_SHIFT in asm/memory.h)
*/
__create_page_tables:
pgtbl r4, r8 @ page table address
/*
* Clear the swapper page table
*/
mov r0, r4
mov r3, #0
add r6, r0, #PG_DIR_SIZE
1: str r3, [r0], #4
str r3, [r0], #4
str r3, [r0], #4
str r3, [r0], #4
teq r0, r6
bne 1b
#ifdef CONFIG_ARM_LPAE
/*
* Build the PGD table (first level) to point to the PMD table. A PGD
* entry is 64-bit wide.
*/
mov r0, r4
add r3, r4, #0x1000 @ first PMD table address
orr r3, r3, #3 @ PGD block type
mov r6, #4 @ PTRS_PER_PGD
mov r7, #1 << (55 - 32) @ L_PGD_SWAPPER
1:
#ifdef CONFIG_CPU_ENDIAN_BE8
str r7, [r0], #4 @ set top PGD entry bits
str r3, [r0], #4 @ set bottom PGD entry bits
#else
str r3, [r0], #4 @ set bottom PGD entry bits
str r7, [r0], #4 @ set top PGD entry bits
#endif
add r3, r3, #0x1000 @ next PMD table
subs r6, r6, #1
bne 1b
add r4, r4, #0x1000 @ point to the PMD tables
#ifdef CONFIG_CPU_ENDIAN_BE8
add r4, r4, #4 @ we only write the bottom word
#endif
#endif
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, __turn_mmu_on_loc
ldmia r0, {r3, r5, r6}
sub r0, r0, r3 @ virt->phys offset
add r5, r5, r0 @ phys __turn_mmu_on
add r6, r6, r0 @ phys __turn_mmu_on_end
mov r5, r5, lsr #SECTION_SHIFT
mov r6, r6, lsr #SECTION_SHIFT
1: orr r3, r7, r5, lsl #SECTION_SHIFT @ flags + kernel base
str r3, [r4, r5, lsl #PMD_ORDER] @ identity mapping
cmp r5, r6
addlo r5, r5, #1 @ next section
blo 1b
/*
* Map our RAM from the start to the end of the kernel .bss section.
*/
add r0, r4, #PAGE_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
ldr r6, =(_end - 1)
orr r3, r8, r7
add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
1: str r3, [r0], #1 << PMD_ORDER
add r3, r3, #1 << SECTION_SHIFT
cmp r0, r6
bls 1b
#ifdef CONFIG_XIP_KERNEL
/*
* Map the kernel image separately as it is not located in RAM.
*/
#define XIP_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
mov r3, pc
mov r3, r3, lsr #SECTION_SHIFT
orr r3, r7, r3, lsl #SECTION_SHIFT
add r0, r4, #(XIP_START & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
str r3, [r0, #((XIP_START & 0x00f00000) >> SECTION_SHIFT) << PMD_ORDER]!
ldr r6, =(_edata_loc - 1)
add r0, r0, #1 << PMD_ORDER
add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
1: cmp r0, r6
add r3, r3, #1 << SECTION_SHIFT
strls r3, [r0], #1 << PMD_ORDER
bls 1b
#endif
/*
* Then map boot params address in r2 if specified.
* We map 2 sections in case the ATAGs/DTB crosses a section boundary.
*/
mov r0, r2, lsr #SECTION_SHIFT
movs r0, r0, lsl #SECTION_SHIFT
subne r3, r0, r8
addne r3, r3, #PAGE_OFFSET
addne r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
orrne r6, r7, r0
strne r6, [r3], #1 << PMD_ORDER
addne r6, r6, #1 << SECTION_SHIFT
strne r6, [r3]
#if defined(CONFIG_ARM_LPAE) && defined(CONFIG_CPU_ENDIAN_BE8)
sub r4, r4, #4 @ Fixup page table pointer
@ for 64-bit descriptors
#endif
#ifdef CONFIG_DEBUG_LL
#if !defined(CONFIG_DEBUG_ICEDCC) && !defined(CONFIG_DEBUG_SEMIHOSTING)
/*
* Map in IO space for serial debugging.
* This allows debug messages to be output
* via a serial console before paging_init.
*/
addruart r7, r3, r0
mov r3, r3, lsr #SECTION_SHIFT
mov r3, r3, lsl #PMD_ORDER
add r0, r4, r3
mov r3, r7, lsr #SECTION_SHIFT
ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
orr r3, r7, r3, lsl #SECTION_SHIFT
#ifdef CONFIG_ARM_LPAE
mov r7, #1 << (54 - 32) @ XN
#ifdef CONFIG_CPU_ENDIAN_BE8
str r7, [r0], #4
str r3, [r0], #4
#else
str r3, [r0], #4
str r7, [r0], #4
#endif
#else
orr r3, r3, #PMD_SECT_XN
str r3, [r0], #4
#endif
#else /* CONFIG_DEBUG_ICEDCC || CONFIG_DEBUG_SEMIHOSTING */
/* we don't need any serial debugging mappings */
ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
#endif
#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 >> (SECTION_SHIFT - PMD_ORDER)
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 >> (SECTION_SHIFT - PMD_ORDER)
orr r3, r7, #0x02000000
str r3, [r0]
add r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER)
str r3, [r0]
#endif
#endif
#ifdef CONFIG_ARM_LPAE
sub r4, r4, #0x1000 @ point to the PGD table
mov r4, r4, lsr #ARCH_PGD_SHIFT
#endif
mov pc, lr
ENDPROC(__create_page_tables)
.ltorg
.align
__turn_mmu_on_loc:
.long .
.long __turn_mmu_on
.long __turn_mmu_on_end
#if defined(CONFIG_SMP)
.text
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.
*/
ARM_BE8(setend be) @ ensure we are in BE8 mode
#ifdef CONFIG_ARM_VIRT_EXT
bl __hyp_stub_install_secondary
#endif
safe_svcmode_maskall 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 (see ARCH_PGD_SHIFT in asm/memory.h)
* 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
#ifndef CONFIG_ARM_LPAE
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
#endif
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
.pushsection .idmap.text, "ax"
ENTRY(__turn_mmu_on)
mov r0, r0
instr_sync
mcr p15, 0, r0, c1, c0, 0 @ write control reg
mrc p15, 0, r3, c0, c0, 0 @ read id reg
instr_sync
mov r3, r3
mov r3, r13
mov pc, r3
__turn_mmu_on_end:
ENDPROC(__turn_mmu_on)
.popsection
#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
mov r6, r3, lsr #24 @ constant for add/sub instructions
teq r3, r6, lsl #24 @ must be 16MiB aligned
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
lsls r6, #24
beq 2f
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 2f
1: add r7, r3
ldrh ip, [r7, #2]
ARM_BE8(rev16 ip, ip)
and ip, 0x8f00
orr ip, r6 @ mask in offset bits 31-24
ARM_BE8(rev16 ip, ip)
strh ip, [r7, #2]
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
bcc 1b
bx lr
#else
b 2f
1: ldr ip, [r7, r3]
#ifdef CONFIG_CPU_ENDIAN_BE8
@ in BE8, we load data in BE, but instructions still in LE
bic ip, ip, #0xff000000
orr ip, ip, r6, lsl#24
#else
bic ip, ip, #0x000000ff
orr ip, ip, r6 @ mask in offset bits 31-24
#endif
str ip, [r7, r3]
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
bcc 1b
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"
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