linux - 调试Linux内核 panic

Question

我是内核调试新手。下面是最后一条内核消息。根据我的理解，它正在尝试访问空指针。但我不明白为什么它要关闭 cup 0。

Unable to handle kernel paging request at virtual address 40025694
[37655.473976] pgd = d7138000
[37655.474007] [40025694] *pgd=9ec1a831, *pte=bf2e659d, *ppte=00000000
[37655.474038] Internal error: Oops: 17 [#1] PREEMPT SMP
[37655.474038] Modules linked in:
[37655.474068] CPU: 1    Not tainted  (3.0.21-g572d9be-00004-g4ec4db2 #1)
[37655.474099] PC is at vector_swi+0x28/0x88
[37655.474129] LR is at 0x40025698
[37655.474160] pc : c01065a8    lr : 40025698    psr : 60000093
[37655.474160] sp : d6eaffb0  ip : 4062c18c  fp : 5ed97c24
[37655.474190] r10: 58702b64  r9 : 5ea56f98  r8 : 20000010
[37655.474221] r7 : 000000a8  r6 : 41b13530  r5 : 4062c270  r4 : 4062c140
[37655.474251] r3 : 00000000  r2 : ffffffff  r1 : 00000001  r0 : 5ed97bd0
[37655.474251] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment user
[37655.474282] Control: 10c5787d  Table: 9ec3806a  DAC: 00000015
[37655.474282] 
[37655.474282] PC: 0xc0106528:
[37655.474312] 6528  e31100ff 1afffff0 e59d1040 e5bde03c e16ff001 f57ff01f e95d7fff e1a00000
[37655.474343] 6548  e28dd00c e1b0f00e eb01ae0e e1a096ad e1a09689 e5991000 e3a08001 e3110c01
[37655.474373] 6568  0affffec e1a0100d e3a00001 eb0006ef eaffffe8 e320f000 e24dd048 e88d1fff
[37655.474404] 6588  e28d803c e9486000 e14f8000 e58de03c e58d8040 e58d0044 e3180020 13a0a000
[37655.474434] 65a8  051ea004 e59fc0ac e59cc000 ee01cf10 f1080080 e1a096ad e1a09689 e28f809c
[37655.474465] 65c8  e3daa4ff 122a7609 159f808c e599a000 e92d0030 e31a0c01 1a000008 e3570f5e
[37655.474465] 65e8  e24fee13 3798f107 e28d1008 e3a08000 e357080f e2270000 2a001084 ea022377
[37655.474526] 6608  e1a02007 e28d1008 e3a00000 eb0006c7 e28fe014 e1a07000 e28d1008 e3570f5e
[37655.474526] 
[37655.474526] SP: 0xd6eaff30:
[37655.474556] ff30  c004815c c004a2c0 c0c02080 0000000a c0d8a580 c017a2f0 c1ef1984 00000012
[37655.474587] ff50  ffffffff d6eaff9c 41b13530 000000a8 20000010 c010602c 5ed97bd0 00000001
[37655.474617] ff70  ffffffff 00000000 4062c140 4062c270 41b13530 000000a8 20000010 5ea56f98
[37655.474648] ff90  58702b64 5ed97c24 4062c18c d6eaffb0 40025698 c01065a8 60000093 ffffffff
[37655.474678] ffb0  5ed97bd0 00000001 ffffffff 00000000 4062c140 4062c270 41b13530 000000a8
[37655.474678] ffd0  5ed97bd0 5ea56f98 58702b64 5ed97c24 4062c18c 5ed97bc8 406283d7 40025698
[37655.474709] fff0  20000010 5ed97bd0 a8afc821 a8afcc21 e033cfc0 40eb3000 40eb6000 d6eb0058
[37655.474739] 0010  d75a9d68 0000079f 00100073 d6eb017d d6eb00cc d6e98f94 00000000 00000000
[37655.474770] Process UEventObserver (pid: 675, stack limit = 0xd6eae2f0)
[37655.474770] Stack: (0xd6eaffb0 to 0xd6eb0000)
[37655.474801] ffa0:                                     5ed97bd0 00000001 ffffffff 00000000
[37655.474801] ffc0: 4062c140 4062c270 41b13530 000000a8 5ed97bd0 5ea56f98 58702b64 5ed97c24
[37655.474831] ffe0: 4062c18c 5ed97bc8 406283d7 40025698 20000010 5ed97bd0 a8afc821 a8afcc21
[37655.474831] Code: e58d8040 e58d0044 e3180020 13a0a000 (051ea004) 
[37655.474862] ---[ end trace 2416079997dfe426 ]---
[37655.474862] Kernel panic - not syncing: Fatal exception
[37655.474892] [<c010cdec>] (unwind_backtrace+0x0/0x12c) from [<c078872c>] (panic+0x80/0x1a4)
[37655.474923] [<c078872c>] (panic+0x80/0x1a4) from [<c010a578>] (die+0x1d4/0x21c)
[37655.474953] [<c010a578>] (die+0x1d4/0x21c) from [<c0111510>] (__do_kernel_fault+0x64/0x84)
[37655.474953] [<c0111510>] (__do_kernel_fault+0x64/0x84) from [<c0111798>] (do_page_fault+0x268/0x288)
[37655.474984] [<c0111798>] (do_page_fault+0x268/0x288) from [<c0100340>] (do_DataAbort+0x134/0x1a4)
[37655.474984] [<c0100340>] (do_DataAbort+0x134/0x1a4) from [<c010602c>] (__dabt_svc+0x4c/0x60)
[37655.475014] Exception stack(0xd6eaff68 to 0xd6eaffb0)
[37655.475014] ff60:                   5ed97bd0 00000001 ffffffff 00000000 4062c140 4062c270
[37655.475014] ff80: 41b13530 000000a8 20000010 5ea56f98 58702b64 5ed97c24 4062c18c d6eaffb0
[37655.475045] ffa0: 40025698 c01065a8 60000093 ffffffff
[37655.475045] [<c010602c>] (__dabt_svc+0x4c/0x60) from [<c01065a8>] (vector_swi+0x28/0x88)
[37655.475075] CPU0: stopping
[37655.475075] [<c010cdec>] (unwind_backtrace+0x0/0x12c) from [<c010b438>] (handle_IPI+0x100/0x1d4)
[37655.475106] [<c010b438>] (handle_IPI+0x100/0x1d4) from [<c010044c>] (gic_handle_irq+0x9c/0xac)
[37655.475106] [<c010044c>] (gic_handle_irq+0x9c/0xac) from [<c0106094>] (__irq_svc+0x54/0x80)
[37655.475136] Exception stack(0xc874bc68 to 0xc874bcb0)
[37655.475136] bc60:                   d3cf4948 cd6dbd54 0000001f 00000000 b1d2a59d 5ea1f000
[37655.475136] bc80: d3cf4948 5ea1f000 00000000 c874a000 d2b9207c d7e55670 5ea1f02b c874bcb0
[37655.475167] bca0: c01eb894 c010bbb4 60000013 ffffffff
[37655.475167] [<c0106094>] (__irq_svc+0x54/0x80) from [<c010bbb4>] (flush_tlb_page+0x8c/0x98)
[37655.475197] [<c010bbb4>] (flush_tlb_page+0x8c/0x98) from [<c01eb894>] (ptep_clear_flush+0x30/0x38)
[37655.475197] [<c01eb894>] (ptep_clear_flush+0x30/0x38) from [<c01e743c>] (try_to_unmap_one+0xc4/0x3a4)
[37655.475228] [<c01e743c>] (try_to_unmap_one+0xc4/0x3a4) from [<c01e77a0>] (try_to_unmap_file+0x84/0x4b4)
[37655.475228] [<c01e77a0>] (try_to_unmap_file+0x84/0x4b4) from [<c01e80b0>] (try_to_unmap+0x34/0x4c)
[37655.475258] [<c01e80b0>] (try_to_unmap+0x34/0x4c) from [<c01d28dc>] (shrink_page_list+0x258/0x78c)
[37655.475258] [<c01d28dc>] (shrink_page_list+0x258/0x78c) from [<c01d31b4>] (shrink_inactive_list+0x1e0/0x330)
[37655.475289] [<c01d31b4>] (shrink_inactive_list+0x1e0/0x330) from [<c01d3704>] (shrink_zone+0x400/0x588)
[37655.475289] [<c01d3704>] (shrink_zone+0x400/0x588) from [<c01d3fd8>] (kswapd+0x594/0x970)
[37655.475319] [<c01d3fd8>] (kswapd+0x594/0x970) from [<c018e04c>] (kthread+0x80/0x88)
[37655.475319] [<c018e04c>] (kthread+0x80/0x88) from [<c01075c0>] (kernel_thread_exit+0x0/0x8)

任何指针，以便我可以继续前进。

谢谢

Answer 1

如果您无法重现 oops，那么您唯一真正的办法就是查看内核的 objdump，并将 oops 中转储的 CPU 状态与变量的位置进行匹配。内核树中曾经有一个指南(Linus 自己写的!):Documentation/oops-tracing.txt 。然而，内核用户手册现在似乎有更多最新的documentation rendered from the source tree .