arch/arm26/lib/backtrace.S

   1 /*
   2  *  linux/arch/arm26/lib/backtrace.S
   3  *
   4  *  Copyright (C) 1995, 1996 Russell King
   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 #include <linux/config.h>
  11 #include <linux/linkage.h>
  12 #include <asm/assembler.h>
  13                 .text
  14
  15 @ fp is 0 or stack frame
  16
  17 #define frame   r4
  18 #define next    r5
  19 #define save    r6
  20 #define mask    r7
  21 #define offset  r8
  22
  23 ENTRY(__backtrace)
  24                 mov     r1, #0x10
  25                 mov     r0, fp
  26
  27 ENTRY(c_backtrace)
  28
  29 #ifdef CONFIG_NO_FRAME_POINTER
  30                 mov     pc, lr
  31 #else
  32
  33                 stmfd   sp!, {r4 - r8, lr}      @ Save an extra register so we have a location...
  34                 mov     mask, #0xfc000003
  35                 tst     mask, r0
  36                 movne   r0, #0
  37                 movs    frame, r0
  38 1:              moveq   r0, #-2
  39                 LOADREGS(eqfd, sp!, {r4 - r8, pc})
  40
  41 2:              stmfd   sp!, {pc}               @ calculate offset of PC in STMIA instruction
  42                 ldr     r0, [sp], #4
  43                 adr     r1, 2b - 4
  44                 sub     offset, r0, r1
  45
  46 3:              tst     frame, mask             @ Check for address exceptions...
  47                 bne     1b
  48
  49 1001:           ldr     next, [frame, #-12]     @ get fp
  50 1002:           ldr     r2, [frame, #-4]        @ get lr
  51 1003:           ldr     r3, [frame, #0]         @ get pc
  52                 sub     save, r3, offset        @ Correct PC for prefetching
  53                 bic     save, save, mask
  54 1004:           ldr     r1, [save, #0]          @ get instruction at function
  55                 mov     r1, r1, lsr #10
  56                 ldr     r3, .Ldsi+4
  57                 teq     r1, r3
  58                 subeq   save, save, #4
  59                 adr     r0, .Lfe
  60                 mov     r1, save
  61                 bic     r2, r2, mask
  62                 bl      printk                  @ print pc and link register
  63
  64                 ldr     r0, [frame, #-8]        @ get sp
  65                 sub     r0, r0, #4
  66 1005:           ldr     r1, [save, #4]          @ get instruction at function+4
  67                 mov     r3, r1, lsr #10
  68                 ldr     r2, .Ldsi+4
  69                 teq     r3, r2                  @ Check for stmia sp!, {args}
  70                 addeq   save, save, #4          @ next instruction
  71                 bleq    .Ldumpstm
  72
  73                 sub     r0, frame, #16
  74 1006:           ldr     r1, [save, #4]          @ Get 'stmia sp!, {rlist, fp, ip, lr, pc}' instruction
  75                 mov     r3, r1, lsr #10
  76                 ldr     r2, .Ldsi
  77                 teq     r3, r2
  78                 bleq    .Ldumpstm
  79
  80                 teq     frame, next
  81                 movne   frame, next
  82                 teqne   frame, #0
  83                 bne     3b
  84                 LOADREGS(fd, sp!, {r4 - r8, pc})
  85
  86 /*
  87  * Fixup for LDMDB
  88  */
  89                 .section .fixup,"ax"
  90                 .align  0
  91 1007:           ldr     r0, =.Lbad
  92                 mov     r1, frame
  93                 bl      printk
  94                 LOADREGS(fd, sp!, {r4 - r8, pc})
  95                 .ltorg
  96                 .previous
  97
  98                 .section __ex_table,"a"
  99                 .align  3
 100                 .long   1001b, 1007b
 101                 .long   1002b, 1007b
 102                 .long   1003b, 1007b
 103                 .long   1004b, 1007b
 104                 .long   1005b, 1007b
 105                 .long   1006b, 1007b
 106                 .previous
 107
 108 #define instr r4
 109 #define reg   r5
 110 #define stack r6
 111
 112 .Ldumpstm:      stmfd   sp!, {instr, reg, stack, r7, lr}
 113                 mov     stack, r0
 114                 mov     instr, r1
 115                 mov     reg, #9
 116                 mov     r7, #0
 117 1:              mov     r3, #1
 118                 tst     instr, r3, lsl reg
 119                 beq     2f
 120                 add     r7, r7, #1
 121                 teq     r7, #4
 122                 moveq   r7, #0
 123                 moveq   r3, #'\n'
 124                 movne   r3, #' '
 125                 ldr     r2, [stack], #-4
 126                 mov     r1, reg
 127                 adr     r0, .Lfp
 128                 bl      printk
 129 2:              subs    reg, reg, #1
 130                 bpl     1b
 131                 teq     r7, #0
 132                 adrne   r0, .Lcr
 133                 blne    printk
 134                 mov     r0, stack
 135                 LOADREGS(fd, sp!, {instr, reg, stack, r7, pc})
 136
 137 .Lfe:           .asciz  "Function entered at [<%p>] from [<%p>]\n"
 138 .Lfp:           .asciz  " r%d = %08X%c"
 139 .Lcr:           .asciz  "\n"
 140 .Lbad:          .asciz  "Backtrace aborted due to bad frame pointer <%p>\n"
 141                 .align
 142 .Ldsi:          .word   0x00e92dd8 >> 2
 143                 .word   0x00e92d00 >> 2
 144
 145 #endif