/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/kernel/head.S
 *
 *  Copyright (C) 1994-2002 Russell King
 *  Copyright (c) 2003 ARM Limited
 *  All Rights Reserved
 *
 *  Kernel startup code for all 32-bit CPUs
 */
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/pgtable.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>

#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        (KERNEL_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

        /*
         * This needs to be assigned at runtime when the linker symbols are
         * resolved. These are unsigned 64bit really, but in this assembly code
         * We store them as 32bit.
         */
        .pushsection .data
        .align  2
        .globl  kernel_sec_start
        .globl  kernel_sec_end
kernel_sec_start:
        .long   0
        .long   0
kernel_sec_end:
        .long   0
        .long   0
        .popsection

        .macro  pgtbl, rd, phys
        add     \rd, \phys, #TEXT_OFFSET
        sub     \rd, \rd, #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( badr    r9, 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_lpae                    @ only classic page table format
#endif

#ifndef CONFIG_XIP_KERNEL
        adr_l   r8, _text                       @ __pa(_text)
        sub     r8, r8, #TEXT_OFFSET            @ PHYS_OFFSET
#else
        ldr     r8, =PLAT_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.
         *
         * The processor init function will be called with:
         *  r1 - machine type
         *  r2 - boot data (atags/dt) pointer
         *  r4 - translation table base (low word)
         *  r5 - translation table base (high word, if LPAE)
         *  r8 - translation table base 1 (pfn if LPAE)
         *  r9 - cpuid
         *  r13 - virtual address for __enable_mmu -> __turn_mmu_on
         *
         * On return, the CPU will be ready for the MMU to be turned on,
         * r0 will hold the CPU control register value, r1, r2, r4, and
         * r9 will be preserved.  r5 will also be preserved if LPAE.
         */
        ldr     r13, =__mmap_switched           @ address to jump to after
                                                @ mmu has been enabled
        badr    lr, 1f                          @ return (PIC) address
#ifdef CONFIG_ARM_LPAE
        mov     r5, #0                          @ high TTBR0
        mov     r8, r4, lsr #12                 @ TTBR1 is swapper_pg_dir pfn
#else
        mov     r8, r4                          @ set TTBR1 to swapper_pg_dir
#endif
        ldr     r12, [r10, #PROCINFO_INITFUNC]
        add     r12, r12, r10
        ret     r12
1:      b       __enable_mmu
ENDPROC(stext)
        .ltorg

/*
 * 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 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_l   r5, __turn_mmu_on               @ _pa(__turn_mmu_on)
        adr_l   r6, __turn_mmu_on_end           @ _pa(__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

        /*
         * The main matter: map in the kernel using section mappings, and
         * set two variables to indicate the physical start and end of the
         * kernel.
         */
        add     r0, r4, #KERNEL_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
        ldr     r6, =(_end - 1)
        adr_l   r5, kernel_sec_start            @ _pa(kernel_sec_start)
#if defined CONFIG_CPU_ENDIAN_BE8 || defined CONFIG_CPU_ENDIAN_BE32
        str     r8, [r5, #4]                    @ Save physical start of kernel (BE)
#else
        str     r8, [r5]                        @ Save physical start of kernel (LE)
#endif
        orr     r3, r8, r7                      @ Add the MMU flags
        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
        eor     r3, r3, r7                      @ Remove the MMU flags
        adr_l   r5, kernel_sec_end              @ _pa(kernel_sec_end)
#if defined CONFIG_CPU_ENDIAN_BE8 || defined CONFIG_CPU_ENDIAN_BE32
        str     r3, [r5, #4]                    @ Save physical end of kernel (BE)
#else
        str     r3, [r5]                        @ Save physical end of kernel (LE)
#endif

#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
        cmp     r2, #0
        ldrne   r3, =FDT_FIXED_BASE >> (SECTION_SHIFT - PMD_ORDER)
        addne   r3, r3, r4
        orrne   r6, r7, r0, lsl #SECTION_SHIFT
        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
#endif
        ret     lr
ENDPROC(__create_page_tables)
        .ltorg

#if defined(CONFIG_SMP)
        .text
        .arm
ENTRY(secondary_startup_arm)
 THUMB( badr    r9, 1f          )       @ Kernel is entered in ARM.
 THUMB( bx      r9              )       @ If this is a Thumb-2 kernel,
 THUMB( .thumb                  )       @ switch to Thumb now.
 THUMB(1:                       )
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_l   r3, secondary_data
        mov_l   r12, __secondary_switched
        ldrd    r4, r5, [r3, #0]                @ get secondary_data.pgdir
ARM_BE8(eor     r4, r4, r5)                     @ Swap r5 and r4 in BE:
ARM_BE8(eor     r5, r4, r5)                     @ it can be done in 3 steps
ARM_BE8(eor     r4, r4, r5)                     @ without using a temp reg.
        ldr     r8, [r3, #8]                    @ get secondary_data.swapper_pg_dir
        badr    lr, __enable_mmu                @ return address
        mov     r13, r12                        @ __secondary_switched address
        ldr     r12, [r10, #PROCINFO_INITFUNC]
        add     r12, r12, r10                   @ initialise processor
                                                @ (return control reg)
        ret     r12
ENDPROC(secondary_startup)
ENDPROC(secondary_startup_arm)

ENTRY(__secondary_switched)
#if defined(CONFIG_VMAP_STACK) && !defined(CONFIG_ARM_LPAE)
        @ Before using the vmap'ed stack, we have to switch to swapper_pg_dir
        @ as the ID map does not cover the vmalloc region.
        mrc     p15, 0, ip, c2, c0, 1   @ read TTBR1
        mcr     p15, 0, ip, c2, c0, 0   @ set TTBR0
        instr_sync
#endif
        adr_l   r7, secondary_data + 12         @ get secondary_data.stack
        ldr     sp, [r7]
        ldr     r0, [r7, #4]                    @ get secondary_data.task
        mov     fp, #0
        b       secondary_start_kernel
ENDPROC(__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.  All these registers need to be preserved by the
 * processor setup function (or set in the case of r0)
 *
 *  r0  = cp#15 control register
 *  r1  = machine ID
 *  r2  = atags or dtb pointer
 *  r4  = TTBR pointer (low word)
 *  r5  = TTBR pointer (high word if LPAE)
 *  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
#ifdef CONFIG_ARM_LPAE
        mcrr    p15, 0, r4, r5, c2              @ load TTBR0
#else
        mov     r5, #DACR_INIT
        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
        ret     r3
__turn_mmu_on_end:
ENDPROC(__turn_mmu_on)
        .popsection


#ifdef CONFIG_SMP_ON_UP
        __HEAD
__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?
        reteq   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?
        bne    __fixup_smp_on_up        @ no, assume UP

        @ Core indicates it is SMP. Check for Aegis SOC where a single
        @ Cortex-A9 CPU is present but SMP operations fault.
        mov     r4, #0x41000000
        orr     r4, r4, #0x0000c000
        orr     r4, r4, #0x00000090
        teq     r3, r4                  @ Check for ARM Cortex-A9
        retne   lr                      @ Not ARM Cortex-A9,

        @ If a future SoC *does* use 0x0 as the PERIPH_BASE, then the
        @ below address check will need to be #ifdef'd or equivalent
        @ for the Aegis platform.
        mrc     p15, 4, r0, c15, c0     @ get SCU base address
        teq     r0, #0x0                @ '0' on actual UP A9 hardware
        beq     __fixup_smp_on_up       @ So its an A9 UP
        ldr     r0, [r0, #4]            @ read SCU Config
ARM_BE8(rev     r0, r0)                 @ byteswap if big endian
        and     r0, r0, #0x3            @ number of CPUs
        teq     r0, #0x0                @ is 1?
        retne   lr

__fixup_smp_on_up:
        adr_l   r4, __smpalt_begin
        adr_l   r5, __smpalt_end
        b       __do_fixup_smp_on_up
ENDPROC(__fixup_smp)

        .pushsection .data
        .align  2
        .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
        reths   lr
        ldmia   r4, {r0, r6}
 ARM(   str     r6, [r0, r4]    )
 THUMB( add     r0, r0, r4      )
        add     r4, r4, #8
#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 r0.
 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
        bl      __do_fixup_smp_on_up
        ldmfd   sp!, {r4 - r6, pc}
ENDPROC(fixup_smp)

#include "head-common.S"