LXR linux/arch/arm/kernel/entry-v7m.S

   1/*
   2 * linux/arch/arm/kernel/entry-v7m.S
   3 *
   4 * Copyright (C) 2008 ARM Ltd.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * Low-level vector interface routines for the ARMv7-M architecture
  11 */
  12#include <asm/memory.h>
  13#include <asm/glue.h>
  14#include <asm/thread_notify.h>
  15#include <asm/v7m.h>
  16
  17#include "entry-header.S"
  18
  19#ifdef CONFIG_TRACE_IRQFLAGS
  20#error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"
  21#endif
  22
  23__invalid_entry:
  24        v7m_exception_entry
  25#ifdef CONFIG_PRINTK
  26        adr     r0, strerr
  27        mrs     r1, ipsr
  28        mov     r2, lr
  29        bl      printk
  30#endif
  31        mov     r0, sp
  32        bl      show_regs
  331:      b       1b
  34ENDPROC(__invalid_entry)
  35
  36strerr: .asciz  "\nUnhandled exception: IPSR = %08lx LR = %08lx\n"
  37
  38        .align  2
  39__irq_entry:
  40        v7m_exception_entry
  41
  42        @
  43        @ Invoke the IRQ handler
  44        @
  45        mrs     r0, ipsr
  46        ldr     r1, =V7M_xPSR_EXCEPTIONNO
  47        and     r0, r1
  48        sub     r0, #16
  49        mov     r1, sp
  50        stmdb   sp!, {lr}
  51        @ routine called with r0 = irq number, r1 = struct pt_regs *
  52        bl      nvic_handle_irq
  53
  54        pop     {lr}
  55        @
  56        @ Check for any pending work if returning to user
  57        @
  58        ldr     r1, =BASEADDR_V7M_SCB
  59        ldr     r0, [r1, V7M_SCB_ICSR]
  60        tst     r0, V7M_SCB_ICSR_RETTOBASE
  61        beq     2f
  62
  63        get_thread_info tsk
  64        ldr     r2, [tsk, #TI_FLAGS]
  65        tst     r2, #_TIF_WORK_MASK
  66        beq     2f                      @ no work pending
  67        mov     r0, #V7M_SCB_ICSR_PENDSVSET
  68        str     r0, [r1, V7M_SCB_ICSR]  @ raise PendSV
  69
  702:
  71        @ registers r0-r3 and r12 are automatically restored on exception
  72        @ return. r4-r7 were not clobbered in v7m_exception_entry so for
  73        @ correctness they don't need to be restored. So only r8-r11 must be
  74        @ restored here. The easiest way to do so is to restore r0-r7, too.
  75        ldmia   sp!, {r0-r11}
  76        add     sp, #S_FRAME_SIZE-S_IP
  77        cpsie   i
  78        bx      lr
  79ENDPROC(__irq_entry)
  80
  81__pendsv_entry:
  82        v7m_exception_entry
  83
  84        ldr     r1, =BASEADDR_V7M_SCB
  85        mov     r0, #V7M_SCB_ICSR_PENDSVCLR
  86        str     r0, [r1, V7M_SCB_ICSR]  @ clear PendSV
  87
  88        @ execute the pending work, including reschedule
  89        get_thread_info tsk
  90        mov     why, #0
  91        b       ret_to_user
  92ENDPROC(__pendsv_entry)
  93
  94/*
  95 * Register switch for ARMv7-M processors.
  96 * r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
  97 * previous and next are guaranteed not to be the same.
  98 */
  99ENTRY(__switch_to)
 100        .fnstart
 101        .cantunwind
 102        add     ip, r1, #TI_CPU_SAVE
 103        stmia   ip!, {r4 - r11}         @ Store most regs on stack
 104        str     sp, [ip], #4
 105        str     lr, [ip], #4
 106        mov     r5, r0
 107        add     r4, r2, #TI_CPU_SAVE
 108        ldr     r0, =thread_notify_head
 109        mov     r1, #THREAD_NOTIFY_SWITCH
 110        bl      atomic_notifier_call_chain
 111        mov     ip, r4
 112        mov     r0, r5
 113        ldmia   ip!, {r4 - r11}         @ Load all regs saved previously
 114        ldr     sp, [ip]
 115        ldr     pc, [ip, #4]!
 116        .fnend
 117ENDPROC(__switch_to)
 118
 119        .data
 120        .align  8
 121/*
 122 * Vector table (64 words => 256 bytes natural alignment)
 123 */
 124ENTRY(vector_table)
 125        .long   0                       @ 0 - Reset stack pointer
 126        .long   __invalid_entry         @ 1 - Reset
 127        .long   __invalid_entry         @ 2 - NMI
 128        .long   __invalid_entry         @ 3 - HardFault
 129        .long   __invalid_entry         @ 4 - MemManage
 130        .long   __invalid_entry         @ 5 - BusFault
 131        .long   __invalid_entry         @ 6 - UsageFault
 132        .long   __invalid_entry         @ 7 - Reserved
 133        .long   __invalid_entry         @ 8 - Reserved
 134        .long   __invalid_entry         @ 9 - Reserved
 135        .long   __invalid_entry         @ 10 - Reserved
 136        .long   vector_swi              @ 11 - SVCall
 137        .long   __invalid_entry         @ 12 - Debug Monitor
 138        .long   __invalid_entry         @ 13 - Reserved
 139        .long   __pendsv_entry          @ 14 - PendSV
 140        .long   __invalid_entry         @ 15 - SysTick
 141        .rept   64 - 16
 142        .long   __irq_entry             @ 16..64 - External Interrupts
 143        .endr
 144