Debugging notes

==Special Registers==
R9 - link return 
R3 - arg[0]
R2 - FP
R1 - SP

GPR01: c02efe54 
GPR02: c02fb27c

==Frame Usage==
FP + 4N ... FP + 0    Parameter N ... Parameter 0  Previous

FP – 4 FP – 8         Function variables           Current
SP + 4                Previous FP value
SP + 0                Return address

SP – 4 SP – 2096      For use by leaf functions w/o function prologue/epilogue  Future
SP – 2100 SP – 2536   For use by exception handlers

==Code around crash==

c0064100 <tick_irq_enter+0x50>:
c0064100:       84 62 00 4c     l.lwz r3,76(r2)
c0064104:       84 81 00 08     l.lwz r4,8(r1)
c0064108:       84 a1 00 0c     l.lwz r5,12(r1)
c006410c:       bc 03 00 00     l.sfeqi r3,0
c0064110:       d4 01 20 00     l.sw 0(r1),r4
c0064114:       d4 01 28 04     l.sw 4(r1),r5
c0064118:       0c 00 00 1e     l.bnf c0064190 <tick_irq_enter+0xe0>
c006411c:       9c 81 00 08     l.addi r4,r1,8
c0064120:       84 42 00 3c     l.lwz r2,60(r2)
c0064124:       bc 02 00 00     l.sfeqi r2,0
c0064128:       13 ff ff ef     l.bf c00640e4 <tick_irq_enter+0x34>
c006412c:       15 00 00 00     l.nop 0x0
c0064130:       18 40 c0 2f     l.movhi r2,0xc02f
c0064134:       84 61 00 00     l.lwz r3,0(r1)
c0064138:       84 81 00 04     l.lwz r4,4(r1)
c006413c:       a8 42 b2 7c     l.ori r2,r2,0xb27c
c0064140:       d4 02 18 58     l.sw 88(r2),r3
c0064144:       d4 02 20 5c     l.sw 92(r2),r4
c0064148:       07 fe 83 26     l.jal c0004de0 <arch_local_save_flags>
c006414c:       15 00 00 00     l.nop 0x0
c0064150:       9c 60 00 00     l.addi r3,r0,0
c0064154:       07 fe 83 2a     l.jal c0004dfc <arch_local_irq_restore>
c0064158:       a8 4b 00 00     l.ori r2,r11,0x0
c006415c:       84 81 00 00     l.lwz r4,0(r1)
c0064160:       84 a1 00 04     l.lwz r5,4(r1)
c0064164:       d4 01 20 08     l.sw 8(r1),r4
c0064168:       d4 01 28 0c     l.sw 12(r1),r5
c006416c:       07 ff fa 10     l.jal c00629ac <tick_do_update_jiffies64>
c0064170:       9c 61 00 08     l.addi r3,r1,8
c0064174:       07 fe 83 22     l.jal c0004dfc <arch_local_irq_restore>
c0064178:       a8 62 00 00     l.ori r3,r2,0x0
c006417c:       9c 21 00 1c     l.addi r1,r1,28
c0064180:       85 21 ff fc     l.lwz r9,-4(r1)
c0064184:       84 21 ff f4     l.lwz r1,-12(r1)
c0064188:       44 00 48 00     l.jr r9
c006418c:       84 41 ff f8     l.lwz r2,-8(r1)
c0064190:       9c 60 00 00     l.addi r3,r0,0
c0064194:       07 ff fa d3     l.jal c0062ce0 <update_ts_time_stats.constprop.26>    <Crash in here>
c0064198:       a8 a3 00 00     l.ori r5,r3,0x0
c006419c:       18 60 c0 2f     l.movhi r3,0xc02f                                     <R9 points here>



c0062ce0 <update_ts_time_stats.constprop.26>:
c0062ce0:       d7 e1 a7 ec     l.sw -20(r1),r20
c0062ce4:       1a 80 c0 2f     l.movhi r20,0xc02f
c0062ce8:       d7 e1 97 e8     l.sw -24(r1),r18
c0062cec:       d7 e1 4f fc     l.sw -4(r1),r9
c0062cf0:       d7 e1 0f dc     l.sw -36(r1),r1
c0062cf4:       d7 e1 17 e0     l.sw -32(r1),r2
c0062cf8:       d7 e1 77 e4     l.sw -28(r1),r14
c0062cfc:       d7 e1 b7 f0     l.sw -16(r1),r22
c0062d00:       d7 e1 c7 f4     l.sw -12(r1),r24
c0062d04:       d7 e1 d7 f8     l.sw -8(r1),r26
c0062d08:       aa 94 b2 7c     l.ori r20,r20,0xb27c
c0062d0c:       9c 21 ff dc     l.addi r1,r1,-36
c0062d10:       84 d4 00 4c     l.lwz r6,76(r20)
c0062d14:       84 44 00 00     l.lwz r2,0(r4)
c0062d18:       bc 06 00 00     l.sfeqi r6,0
c0062d1c:       85 c4 00 04     l.lwz r14,4(r4)
c0062d20:       0c 00 00 90     l.bnf c0062f60 <update_ts_time_stats.constprop.26+0x280>
c0062d24:       aa 45 00 00     l.ori r18,r5,0x0
c0062d28:       bc 12 00 00     l.sfeqi r18,0
c0062d2c:       10 00 00 66     l.bf c0062ec4 <update_ts_time_stats.constprop.26+0x1e4>
c0062d30:       b8 a2 00 9f     l.srai r5,r2,0x1f
c0062d34:       9c c0 00 01     l.addi r6,r0,1
c0062d38:       e0 65 70 05     l.xor r3,r5,r14
c0062d3c:       e3 03 28 02     l.sub r24,r3,r5
c0062d40:       e4 58 18 00     l.sfgtu r24,r3
c0062d44:       0c 00 00 77     l.bnf c0062f20 <update_ts_time_stats.constprop.26+0x240>
c0062d48:       e2 85 10 05     l.xor r20,r5,r2
c0062d4c:       e0 b4 28 02     l.sub r5,r20,r5
c0062d50:       9c 60 00 00     l.addi r3,r0,0
c0062d54:       e2 85 30 02     l.sub r20,r5,r6
c0062d58:       18 c0 8d 4f     l.movhi r6,0x8d4f
c0062d5c:       a8 98 00 00     l.ori r4,r24,0x0
c0062d60:       9c a0 00 00     l.addi r5,r0,0
c0062d64:       a8 c6 df 3b     l.ori r6,r6,0xdf3b
c0062d68:       04 03 3c fe     l.jal c0132160 <__muldi3>
c0062d6c:       9d c0 00 01     l.addi r14,r0,1
c0062d70:       18 60 72 b0     l.movhi r3,0x72b0
c0062d74:       a8 63 20 c4     l.ori r3,r3,0x20c4
c0062d78:       e4 4c 18 00     l.sfgtu r12,r3
c0062d7c:       18 60 8d 4f     l.movhi r3,0x8d4f
c0062d80:       a8 63 df 3b     l.ori r3,r3,0xdf3b

Openrisc linux crash

Crash with no load
[    0.000000] Linux version 4.5.0-de0_nano-01281-g8b6aa7a (shorne@lianli.shorne-pla.net) (gcc version 4.9.2 (GCC) )
...
[239707.650000] Unable to handle kernel access at virtual address 0xbffe2ce0
[239707.650000]
[239707.650000] Oops#: 0000
[239707.650000] CPU #: 0
[239707.650000]    PC: bffe2ce0    SR: 00008079    SP: c02efe54
[239707.650000] GPR00: 00000000 GPR01: c02efe54 GPR02: c02fb27c GPR03: 00000000
[239707.650000] GPR04: c02efe5c GPR05: 00000000 GPR06: a0000000 GPR07: c0000000
[239707.650000] GPR08: 00726000 GPR09: c006419c GPR10: c02ee000 GPR11: c02efe5c
[239707.650000] GPR12: c0000000 GPR13: 0000a000 GPR14: 00000000 GPR15: 00000000
[239707.650000] GPR16: 00000000 GPR17: 016d4e81 GPR18: c0303096 GPR19: 00000000
[239707.650000] GPR20: c0303096 GPR21: 0000025f GPR22: 00000000 GPR23: 00058610
[239707.650000] GPR24: c02ee000 GPR25: 00000000 GPR26: 00000006 GPR27: 00000000
[239707.650000] GPR28: 00000000 GPR29: c02f0000 GPR30: ffffffff GPR31: cd998d17
[239707.650000]   RES: c02efe5c oGPR11: ffffffff
[239707.650000] Process swapper (pid: 0, stackpage=c02f62d0)
[239707.650000]
Stack: Stack dump [0xc02efd48]:
[239707.650000] sp + 00: 0xc02efe54
[239707.650000] sp + 04: 0xc02fb27c
[239707.650000] sp + 08: 0x00000000
[239707.650000] sp + 12: 0xc02efe5c
[239707.650000] sp + 16: 0x00000000
[239707.650000] sp + 20: 0xa0000000
[239707.650000] sp + 24: 0xc0000000
[239707.650000] sp + 28: 0x00726000
[239707.650000] sp + 32: 0xc006419c  - tick_irq_enter+0xec
[239707.650000] sp + 36: 0xc02ee000
[239707.650000] sp + 40: 0xc02efe5c
[239707.650000] sp + 44: 0xc0000000
[239707.650000] sp + 48: 0x0000a000
[239707.650000] sp + 52: 0x00000000
[239707.650000] sp + 56: 0x00000000
[239707.650000] sp + 60: 0x00000000
[239707.650000] sp + 64: 0x016d4e81
[239707.650000] sp + 68: 0xc0303096
[239707.650000] sp + 72: 0x00000000
[239707.650000] sp + 76: 0xc0303096
[239707.650000] sp + 80: 0x0000025f
[239707.650000] sp + 84: 0x00000000
[239707.650000] sp + 88: 0x00058610
[239707.650000] sp + 92: 0xc02ee000
[239707.650000] sp + 96: 0x00000000
[239707.650000] sp + 100: 0x00000006
[239707.650000] sp + 104: 0x00000000
[239707.650000] sp + 108: 0x00000000
[239707.650000] sp + 112: 0xc02f0000

[239707.650000] sp + 116: 0xffffffff
[239707.650000] sp + 120: 0xcd998d17
[239707.650000] sp + 124: 0xbffe2ce0 - PC ?  (bffe2ce0)
[239707.650000] sp + 128: 0xffffffff
[239707.650000] sp + 132: 0xc02f6ca0
[239707.650000] sp + 136: 0x0000da03
[239707.650000] sp + 140: 0x00000000
[239707.650000] sp + 144: 0x57a22080
[239707.650000] sp + 148: 0x00000001
[239707.650000] sp + 152: 0xc02f6ca0
[239707.650000] sp + 156: 0x00000001
[239707.650000] sp + 160: 0xc02efdf0
[239707.650000] sp + 164: 0xc02f6ca0
[239707.650000] sp + 168: 0xc0303096
[239707.650000] sp + 172: 0x0000da03
[239707.650000] sp + 176: 0x495855e4
[239707.650000] sp + 180: 0xc02efe18
[239707.650000] sp + 184: 0x00000001
[239707.650000] sp + 188: 0xc02f6ca0
[239707.650000] sp + 192: 0x0000da03
[239707.650000] sp + 196: 0x57a22080
[239707.650000] sp + 200: 0xc02fb27c
[239707.650000] sp + 204: 0xc0062738 - tick_program_event+0x74
[239707.650000] sp + 208: 0x0000da03
[239707.650000] sp + 212: 0x57a22080
[239707.650000] sp + 216: 0xc02efe38
[239707.650000] sp + 220: 0xc02efe2c
[239707.650000] sp + 224: 0x00b71e06
[239707.650000] sp + 228: 0xc02efe54
[239707.650000] sp + 232: 0xc02fb27c
[239707.650000] sp + 236: 0x00000000
[239707.650000] sp + 240: 0xc0303096
[239707.650000] sp + 244: 0xc0303096
[239707.650000] sp + 248: 0x00000000
[239707.650000] sp + 252: 0xc02ee000
[239707.650000] sp + 256: 0x00000006
[239707.650000] sp + 260: 0x00000000
[239707.650000] sp + 264: 0xc0064100 - tick_irq_enter+0x50
[239707.650000] sp + 268: 0x0000da03
[239707.650000] sp + 272: 0x57a25cf8
[239707.650000] sp + 276: 0x0000da03
[239707.650000] sp + 280: 0x57a25cf8
[239707.650000] sp + 284: 0xc02efe70
[239707.650000] sp + 288: 0x00010000
[239707.650000] sp + 292: 0xc000e8bc
[239707.650000] sp + 296: 0xc02efe7c
[239707.650000] sp + 300: 0xc02fcb2c
[239707.650000] sp + 304: 0xc0004da0

[239707.650000] sp + 308: 0xc02efe8c
[239707.650000] sp + 312: 0xc02ee000
[239707.650000] sp + 316: 0x00000000
[239707.650000] sp + 320: 0xc000543c
[239707.650000] sp + 324: 0x0000827f
[239707.650000] sp + 328: 0xc02eff9c
[239707.650000] sp + 332: 0xc02ee000
[239707.650000] sp + 336: 0x00000000
[239707.650000] sp + 340: 0x00008679
[239707.650000] sp + 344: 0xfffeffff
[239707.650000] sp + 348: 0xc02fb27c
[239707.650000] sp + 352: 0x029d0000
[239707.650000] sp + 356: 0x00a7358c
[239707.650000] sp + 360: 0xc0038908
[239707.650000] sp + 364: 0xc02ee000
[239707.650000] sp + 368: 0x00000000
[239707.650000] sp + 372: 0x029d28b8
[239707.650000] sp + 376: 0x00000ccc
[239707.650000] sp + 380: 0x00000000
[239707.650000] sp + 384: 0x0a74029d
[239707.650000] sp + 388: 0x00000000
[239707.650000] sp + 392: 0x016d4e81
[239707.650000] sp + 396: 0xc0303096
[239707.650000] sp + 400: 0x00000000
[239707.650000] sp + 404: 0xc0303096
[239707.650000] sp + 408: 0x0000025f
[239707.650000] sp + 412: 0x00000000
[239707.650000] sp + 416: 0x00058610
[239707.650000] sp + 420: 0xc02ee000
[239707.650000] sp + 424: 0x00000000
[239707.650000] sp + 428: 0x00000006
[239707.650000] sp + 432: 0x00000000
[239707.650000] sp + 436: 0x00000000
[239707.650000] sp + 440: 0xc02f0000
[239707.650000] sp + 444: 0xc0308784
[239707.650000] sp + 448: 0xcd998d17
[239707.650000] sp + 452: 0xc0038908
[239707.650000] sp + 456: 0xffffffff
[239707.650000] sp + 460: 0xc0004e1c
[239707.650000] sp + 464: 0xffffffff
[239707.650000] sp + 468: 0xc0038af0
[239707.650000] sp + 472: 0xffffffff
[239707.650000] sp + 476: 0x0000da03
[239707.650000] sp + 480: 0x38161b68
[239707.650000] sp + 484: 0xc02eff48
[239707.650000] sp + 488: 0x00000001

[239707.650000] sp + 492: 0xc02f6ca0
[239707.650000] sp + 496: 0x0000da03
[239707.650000] sp + 500: 0x4527e700
[239707.650000] sp + 504: 0xc02fb27c
[239707.650000] sp + 508: 0xc0062738 - tick_program_event+0x74
[239707.650000] sp + 512: 0x0000da03
[239707.650000] sp + 516: 0x4527e700
[239707.650000] sp + 520: 0xc02eff68
[239707.650000] sp + 524: 0xc02fb27c
[239707.650000] sp + 528: 0x0000da03
[239707.650000] sp + 532: 0x38157640
[239707.650000] sp + 536: 0x0000da03
[239707.650000] sp + 540: 0xc0063380 - __tick_nohz_idle_enter.constprop.23+0x260
[239707.650000] sp + 544: 0xc02eff9c
[239707.650000] sp + 548: 0x0000da03
[239707.650000] sp + 552: 0x4527e700
[239707.650000] sp + 556: 0xc02effa0
[239707.650000] sp + 560: 0xc05a2aa8
[239707.650000] sp + 564: 0xc05a2aa8
[239707.650000] sp + 568: 0xc0303096
[239707.650000] sp + 572: 0xc0303096
[239707.650000] sp + 576: 0xc02ee000
[239707.650000] sp + 580: 0xc02eff94
[239707.650000] sp + 584: 0xc02ee000
[239707.650000] sp + 588: 0xc02eff9c
[239707.650000] sp + 592: 0xc0038908
[239707.650000] sp + 596: 0xc02effac
[239707.650000] sp + 600: 0xc05a2aa8
[239707.650000] sp + 604: 0xc05a2aa8
[239707.650000] sp + 608: 0xc0038ac4
[239707.650000] sp + 612: 0xc02effd0
[239707.650000] sp + 616: 0x00000000
[239707.650000] sp + 620: 0xc05a204c
[239707.650000] sp + 624: 0xc031d5d4
[239707.650000] sp + 628: 0xc1ffd0e0
[239707.650000] sp + 632: 0xc05a200c
[239707.650000] sp + 636: 0x00000000
[239707.650000] sp + 640: 0x00000000
[239707.650000] sp + 644: 0xc026ccb0
[239707.650000] sp + 648: 0xc02effd8
[239707.650000] sp + 652: 0xc0308bec
[239707.650000] sp + 656: 0x00000000
[239707.650000] sp + 660: 0xc0308408
[239707.650000] sp + 664: 0xc031d5d4
[239707.650000] sp + 668: 0xc02f0000
[239707.650000] sp + 672: 0x00000000

[239707.650000] sp + 676: 0x00000000
[239707.650000] sp + 680: 0x00000000
[239707.650000] sp + 684: 0x00000000
[239707.650000] sp + 688: 0x00000000
[239707.650000] sp + 692: 0x00000000
[239707.650000]
[239707.650000]  [<c0000000>]
[239707.650000]  [<c006419c>] - ret
[239707.650000]  [<c0000000>]
[239707.650000]  [<c0062738>]
[239707.650000]  [<c0064100>]
[239707.650000]  [<c000e8bc>]
[239707.650000]  [<c0004da0>]
[239707.650000]  [<c000543c>]
[239707.650000]  [<c0038908>]
[239707.650000]  [<c0308784>]
[239707.650000]  [<c0038908>]
[239707.650000]  [<c0004e1c>]
[239707.650000]  [<c0038af0>]
[239707.650000]  [<c0062738>]
[239707.650000]  [<c0063380>]
[239707.650000]  [<c0038908>]
[239707.650000]  [<c0038ac4>]
[239707.650000]  [<c026ccb0>]
[239707.650000]  [<c0308bec>]
[239707.650000]  [<c0308408>]
[239707.650000]  =======================
[239707.650000]
Code:  Bad PC value.
[239707.650000]
[239707.650000]
[239707.650000] UNHANDLED_EXCEPTION: entering infinite loop