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 <mach/entry-macro.S>
  18
  19 #include "entry-header.S"
  20
  21 #ifdef CONFIG_TRACE_IRQFLAGS
  22 #error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"
  23 #endif
  24
  25 __invalid_entry:
  26         v7m_exception_entry
  27         adr     r0, strerr
  28         mrs     r1, ipsr
  29         mov     r2, lr
  30         bl      printk
  31         mov     r0, sp
  32         bl      show_regs
  33 1:      b       1b
  34 ENDPROC(__invalid_entry)
  35
  36 strerr: .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_do_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
  70 2:
  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
  79 ENDPROC(__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
  92 ENDPROC(__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  */
  99 ENTRY(__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
 117 ENDPROC(__switch_to)
 118
 119         .data
 120         .align  8
 121 /*
 122  * Vector table (64 words => 256 bytes natural alignment)
 123  */
 124 ENTRY(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