/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * linux/arch/arm/kernel/entry-v7m.S
 *
 * Copyright (C) 2008 ARM Ltd.
 *
 * Low-level vector interface routines for the ARMv7-M architecture
 */
#include <asm/page.h>
#include <asm/glue.h>
#include <asm/thread_notify.h>
#include <asm/v7m.h>

#include "entry-header.S"

#ifdef CONFIG_TRACE_IRQFLAGS
#error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"
#endif

__invalid_entry:
        v7m_exception_entry
#ifdef CONFIG_PRINTK
        adr     r0, strerr
        mrs     r1, ipsr
        mov     r2, lr
        bl      _printk
#endif
        mov     r0, sp
        bl      show_regs
1:      b       1b
ENDPROC(__invalid_entry)

strerr: .asciz  "\nUnhandled exception: IPSR = %08lx LR = %08lx\n"

        .align  2
__irq_entry:
        v7m_exception_entry

        @
        @ Invoke the IRQ handler
        @
        mov     r0, sp
        ldr_this_cpu sp, irq_stack_ptr, r1, r2

        @
        @ If we took the interrupt while running in the kernel, we may already
        @ be using the IRQ stack, so revert to the original value in that case.
        @
        subs    r2, sp, r0              @ SP above bottom of IRQ stack?
        rsbscs  r2, r2, #THREAD_SIZE    @ ... and below the top?
        movcs   sp, r0

        push    {r0, lr}                @ preserve LR and original SP

        @ routine called with r0 = struct pt_regs *
        bl      generic_handle_arch_irq

        pop     {r0, lr}
        mov     sp, r0

        @
        @ Check for any pending work if returning to user
        @
        ldr     r1, =BASEADDR_V7M_SCB
        ldr     r0, [r1, V7M_SCB_ICSR]
        tst     r0, V7M_SCB_ICSR_RETTOBASE
        beq     2f

        get_thread_info tsk
        ldr     r2, [tsk, #TI_FLAGS]
        movs    r2, r2, lsl #16
        beq     2f                      @ no work pending
        mov     r0, #V7M_SCB_ICSR_PENDSVSET
        str     r0, [r1, V7M_SCB_ICSR]  @ raise PendSV

2:
        @ registers r0-r3 and r12 are automatically restored on exception
        @ return. r4-r7 were not clobbered in v7m_exception_entry so for
        @ correctness they don't need to be restored. So only r8-r11 must be
        @ restored here. The easiest way to do so is to restore r0-r7, too.
        ldmia   sp!, {r0-r11}
        add     sp, #PT_REGS_SIZE-S_IP
        cpsie   i
        bx      lr
ENDPROC(__irq_entry)

__pendsv_entry:
        v7m_exception_entry

        ldr     r1, =BASEADDR_V7M_SCB
        mov     r0, #V7M_SCB_ICSR_PENDSVCLR
        str     r0, [r1, V7M_SCB_ICSR]  @ clear PendSV

        @ execute the pending work, including reschedule
        get_thread_info tsk
        mov     why, #0
        b       ret_to_user_from_irq
ENDPROC(__pendsv_entry)

/*
 * Register switch for ARMv7-M processors.
 * r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
 * previous and next are guaranteed not to be the same.
 */
ENTRY(__switch_to)
        .fnstart
        .cantunwind
        add     ip, r1, #TI_CPU_SAVE
        stmia   ip!, {r4 - r11}         @ Store most regs on stack
        str     sp, [ip], #4
        str     lr, [ip], #4
        mov     r5, r0
        mov     r6, r2                  @ Preserve 'next'
        add     r4, r2, #TI_CPU_SAVE
        ldr     r0, =thread_notify_head
        mov     r1, #THREAD_NOTIFY_SWITCH
        bl      atomic_notifier_call_chain
        mov     r0, r5
        mov     r1, r6
        ldmia   r4, {r4 - r12, lr}      @ Load all regs saved previously
        set_current r1, r2
        mov     sp, ip
        bx      lr
        .fnend
ENDPROC(__switch_to)

        .data
#if CONFIG_CPU_V7M_NUM_IRQ <= 112
        .align  9
#else
        .align  10
#endif

/*
 * Vector table (Natural alignment need to be ensured)
 */
ENTRY(vector_table)
        .long   0                       @ 0 - Reset stack pointer
        .long   __invalid_entry         @ 1 - Reset
        .long   __invalid_entry         @ 2 - NMI
        .long   __invalid_entry         @ 3 - HardFault
        .long   __invalid_entry         @ 4 - MemManage
        .long   __invalid_entry         @ 5 - BusFault
        .long   __invalid_entry         @ 6 - UsageFault
        .long   __invalid_entry         @ 7 - Reserved
        .long   __invalid_entry         @ 8 - Reserved
        .long   __invalid_entry         @ 9 - Reserved
        .long   __invalid_entry         @ 10 - Reserved
        .long   vector_swi              @ 11 - SVCall
        .long   __invalid_entry         @ 12 - Debug Monitor
        .long   __invalid_entry         @ 13 - Reserved
        .long   __pendsv_entry          @ 14 - PendSV
        .long   __invalid_entry         @ 15 - SysTick
        .rept   CONFIG_CPU_V7M_NUM_IRQ
        .long   __irq_entry             @ External Interrupts
        .endr
        .align  2
        .globl  exc_ret
exc_ret:
        .space  4