如何解讀內(nèi)核的oops

OOPS信息解讀

root@firefly:~/mnt/module#insmodoops_module.ko
[867.140514]UnabletohandlekernelNULLpointerdereferenceatvirtualaddress00000000
[867.141279]pgd=ffffffc0f0a65000
[867.141582][00000000]*pgd=0000000000000000,*pud=0000000000000000
[867.142164]Internalerror:Oops:96000045[#1]SMP
[867.142592]Moduleslinkedin:oops_module(O+)
[867.143006]CPU:4PID:1163Comm:insmodTainted:GO4.4.194+#7
[867.143649]Hardwarename:Firefly-RK3399Board(LinuxOpensource)(DT)
[867.144236]task:ffffffc0cdc44380task.stack:ffffffc00a4fc000
[867.144761]PCisatinit_oopsdemo+0x24/0x38[oops_module]
[867.145247]LRisatinit_oopsdemo+0x18/0x38[oops_module]
[867.145732]pc:[]lr:[]pstate:40000145
[867.146386]sp:ffffffc00a4ffc40
[867.146688]x29:ffffffc00a4ffc40x28:ffffff80081376d0
[867.147178]x27:0000000000000001x26:ffffffc0cde6e880
[867.147491]x25:0000000000000001x24:ffffff8000ef2050
[867.147495]x23:0000000000000000x22:ffffff80095b7860
[867.147498]x21:ffffffc0cdce10c0x20:ffffff80095b7860
[867.147501]x19:ffffff8000ef0000x18:ffffff80897bfa97
[867.147504]x17:0000007fb096c8a0x16:ffffff800813b204Segmentationfau
lt
[867.147508]x15:0000000000000000root@firefly:~/mx14:00000000000224d6nt/module#
[867.147511]x13:000000000000000ax12:0000000000000030
[867.147515]x11:00000000fffffffex10:ffffff80097bfa9f
[867.147518]x9:0000000005f5e0ffx8:ffffff8008463c3c
[867.147522]x7:ffffff80096280b0x6:0000000000000022
[867.147525]x5:ffffffc0f7f24b38x4:0000000000000001
[867.147528]x3:0000000000000007x2:0000000000000007
[867.147534]x1:0000000019760817x0:0000000000000000
[867.147536]
[867.147536]PC:0xffffff8000eeffa4:
[867.147550]ffa4****************************************************************
[867.147561]ffc4****************************************************************
[867.147572]ffe4********************************************************a9bf7bfd
[867.147581]0004910003fdaa1e03e0d503201f5800010095ca7426d2800000528102e172a32ec1
[867.147590]0024b9000001a8c17bfdd65f03c000ef1024ffffff80a9bf7bfd910003fdaa1e03e0
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[867.147607]00640000000000000000000000000000000000000000000000000000000000000000
[867.147616]00840000000000000000000000000000000000000000000000000000000000000000
[867.147618]
[867.147618]LR:0xffffff8000eeff98:
[867.147629]ff98****************************************************************
[867.147639]ffb8****************************************************************
[867.147650]ffd8****************************************************************
[867.147659]fff8****************a9bf7bfd910003fdaa1e03e0d503201f5800010095ca7426
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[867.147695]
[867.147695]SP:0xffffffc00a4ffbc0:
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[867.147785]
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[867.147836]4b580000000001400000000000000000e29300000000000000000000000000000000
[867.147845]4b780000000000000000d591d591dead4eadffffffff00000000ffffffffffffffff
[867.147853]4b9800000000000000000008a70b000000010008a701000000010000000d00000000
[867.147855]
[867.147855]X7:0xffffff8009628030:
[867.147863]8030f26a3900ffffffc0000000000000000000000000000000000011000000000000
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[867.147880]80700000000000000000000000000000000000000001000000000000000000000000
[867.147889]80900000000000000001000000000000000100000002000000010000000100000000
[867.147897]80b000000000000000000927e623ffffff8004e804e8dead4eadffffffff00000000
[867.147905]80d0fffffffffffffffff2000000ffffffc000040000000000000000000100000000
[867.147914]80f000000000dead4eadffffffff00000000ffffffffffffffff09628108ffffff80
[867.147922]811009628108ffffff80000000000000000000000000000000000000000000000000
[867.147924]
[867.147924]X8:0xffffff8008463bbc:
[867.147933]3bbc9400054aaa1303e09400055452800000a94153f3f94013f5a8c37bfdd65f03c0
[867.147942]3bdcf940041317fffff6f940081317fffff4f9400c1317fffff2128002a017fffff5
[867.147950]3bfc71001c1f54000161f9405ce0f9400c00b4000140a9bf7bfdaa0603e2aa0403e1
[867.147959]3c1c910003fd940004cea8c17bfdd65f03c0128002a0d65f03c012800160d65f03c0
[867.147967]3c3ca9bb7bfd7100081f910003fda9025bf5aa0403f6a90153f3aa0603f5a90363f7
[867.147975]3c5cf9405cf354000181f9400660b4000a202a1503e2aa1603e19400047d52800000
[867.147984]3c7ca94153f3a9425bf5a94363f7a8c57bfdd65f03c071000c1f54000061f9400a60
[867.147992]3c9c17fffff371001c1f54000061f9400e6017ffffef35000820510004207100041f
[867.147994]
[867.147994]X10:0xffffff80097bfa1f:
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[867.148020]fa5c0000000000000000000000000000000000000000000000000000000000000000
[867.148028]fa7c000000000000000000000000000000000000000000000001000000003820205b
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[867.148074]
[867.148074]X16:0xffffff800813b184:
[867.148083]b184fa4130029a9f87e2b4000202aa1303e2aa1403e1aa1503e0940e73e9b5000220
[867.148093]b1a4943672e08b1302b58b130294eb1302f754fffde152800002aa1603e1910163a0
[867.148101]b1c497fff7ff17ffffc6aa1303e252800001aa1503e0940e775aaa1303e017fffff0
[867.148110]b1e4f9402fa094021fc6128001a017ffffbc128000e017ffffba1280016017ffffb8
[867.148118]b204a9b67bfd910003fda90153f3f90013f5aa0003f5aa1e03e0aa0103f4aa0203f3
[867.148127]b224d503201fa903ffbfa904ffbfa905ffbfa906ffbfa907ffbfa908ffbff9004fbf
[867.148135]b24497ffefb2340000c093407c00a94153f3f94013f5a8ca7bfdd65f03c0f000b220
[867.148143]b264913d0000910aa00079404401361000e1d00088a12a1303e4aa1403e32a1503e2
[867.148146]
[867.148146]X18:0xffffff80897bfa17:
[867.148157]fa14****************************************************************
[867.148167]fa34****************************************************************
[867.148178]fa54****************************************************************
[867.148189]fa74****************************************************************
[867.148199]fa94****************************************************************
[867.148210]fab4****************************************************************
[867.148221]fad4****************************************************************
[867.148232]faf4****************************************************************
[867.148243]fb14****************************************************************
[867.148244]
[867.148244]X19:0xffffff8000eeff80:
[867.148256]ff80****************************************************************
[867.148271]ffa0****************************************************************
[867.148282]ffc0****************************************************************
[867.148293]ffe0****************************************************************
[867.148303]0000a9bf7bfd910003fdaa1e03e0d503201f5800010095ca7426d2800000528102e1
[867.148311]002072a32ec1b9000001a8c17bfdd65f03c000ef1024ffffff80a9bf7bfd910003fd
[867.148320]0040aa1e03e0d503201f5800008095ca7418a8c17bfdd65f03c000ef1038ffffff80
[867.148328]00600000000000000000000000000000000000000000000000000000000000000000
[867.148330]
[867.148330]X20:0xffffff80095b77e0:
[867.148338]77e00000000000000000000000000000000000000000000000000000000000000000
[867.148346]78000000000000000000000000000000000000000000000000000000000000000000
[867.148355]78200000000000000000000000000000000000000000000000000000000000000000
[867.148363]78400000000000000000000000000000000000000000000000000000000000000000
[867.148372]7860095b7860ffffff80095b7860ffffff80000000010000000000005dc000000000
[867.148380]788000000009756e694c000000780000000000000000000000000000000000000000
[867.148388]78a00000000000000000000000000000000000000000000000000000000000000000
[867.148397]78c00000000072696600796c66650000000000000000000000000000000000000000
[867.148398]
[867.148398]X21:0xffffffc0cdce1040:
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[867.148415]1060000000010000000000000000000000000000000000000000055aab5600000000
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[867.148433]10a00000000000000000000003dd6c62010e6c6b63612e747369666e6f6300000000
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[867.148449]10e000000000000000000000000f2e2e020200000000000000000000000000000000
[867.148458]11000000000000000000000000000000000000000000000000000000000000000000
[867.148466]11200000000000000000000000000000000000000000000000000000000000000000
[867.148468]
[867.148468]X22:0xffffff80095b77e0:
[867.148476]77e00000000000000000000000000000000000000000000000000000000000000000
[867.148484]78000000000000000000000000000000000000000000000000000000000000000000
[867.148493]78200000000000000000000000000000000000000000000000000000000000000000
[867.148501]78400000000000000000000000000000000000000000000000000000000000000000
[867.148510]7860095b7860ffffff80095b7860ffffff80000000010000000000005dc000000000
[867.148518]788000000009756e694c000000780000000000000000000000000000000000000000
[867.148526]78a00000000000000000000000000000000000000000000000000000000000000000
[867.148535]78c00000000072696600796c66650000000000000000000000000000000000000000
[867.148536]
[867.148536]X24:0xffffff8000ef1fd0:
[867.148545]1fd00000000000000000000000000000000000000000000000000000000000000000
[867.148553]1ff0000000000000000000000000000000000000000100000000095cd3a0ffffff80
[867.148562]2010095cd3a0ffffff8073706f6f646f6d5f00656c75000000000000000000000000
[867.148570]20300000000000000000000000000000000000000000000000000000000000000000
[867.148578]2050f089a080ffffffc0f26add00ffffffc0f2117e88ffffffc0f26add28ffffffc0
[867.148588]2070f26add00ffffffc0095c4c08ffffff80dbb66f78ffffffc00000000300000007
[867.148596]209000ef2000ffffff80000000000000000000000000000000000000000000000000
[867.148605]20b0f2f99c00ffffffc000000000000000000000000000000000f089ab40ffffffc0
[867.148606]
[867.148606]X26:0xffffffc0cde6e800:
[867.148615]e8000000000100000000d11d71a8ffffffc000000000000000000000000000000000
[867.148623]e820cf2e6030ffffffc000000000000000000000046d00000000095c42c8ffffff80
[867.148632]e8400000000000000000f7ec5e68ffffffc000000000000000000000000000000000
[867.148640]e8600000000000000000000000000000000000000000000000000000000000000000
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[867.148665]e8c00000000000000000000000000000000000000000000000000000000000000000
[867.148674]e8e00000000000000000000000000000000000000000000000000000000000000000
[867.148675]
[867.148675]X28:0xffffff8008137650:
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[867.148718]76d0a9be7bfd910003fda90153f3aa0003f4aa0203f3aa1e03e0d503201faa1303e0
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[867.148735]7710a9be7bfd910003fda90153f3aa0003f3aa0103f4aa1e03e0d503201f52801801
[867.148743]7730aa1403e072a048019401c11af9006260a94153f3a8c27bfdd65f03c0a9be7bfd
[867.148745]
[867.148745]X29:0xffffffc00a4ffbc0:
[867.148754]fbc0095b7860ffffff80000000000000000000ef2050ffffff800000000100000000
[867.148763]fbe0cde6e880ffffffc00000000100000000081376d0ffffff800a4ffc40ffffffc0
[867.148771]fc0000ef0018ffffff800a4ffc40ffffffc000ef0024ffffff804000014500000000
[867.148780]fc20ee9ae0000000004000012ffb0000000000000000000000800000000000000000
[867.148790]fc400a4ffc50ffffffc0080830f8ffffff800a4ffcd0ffffffc00818d2d0ffffff80
[867.148798]fc6000ef2000ffffff80095cd000ffffff80cde6e8c8ffffffc0cdce1140ffffffc0
[867.148807]fc8000000000000000000818d2a4ffffff8000ef2000ffffff80095cd000ffffff80
[867.148815]fca0cde6e8c8ffffffc0095cd000ffffff80000000000000000000ef2050ffffff80
[867.148816]
[867.148820]Processinsmod(pid:1163,stacklimit=0xffffffc00a4fc000)
[867.148822]Stack:(0xffffffc00a4ffc40to0xffffffc00a500000)
[867.148826]fc40:ffffffc00a4ffc50ffffff80080830f8ffffffc00a4ffcd0ffffff800818d2d0
[867.148829]fc60:ffffff8000ef2000ffffff80095cd000ffffffc0cde6e8c8ffffffc0cdce1140
[867.148832]fc80:0000000000000000ffffff800818d2a4ffffff8000ef2000ffffff80095cd000
[867.148834]fca0:ffffffc0cde6e8c8ffffff80095cd0000000000000000000ffffff8000ef2050
[867.148837]fcc0:0000000000000001ffffffc0cde6e880ffffffc00a4ffd00ffffff800813ab5c
[867.148840]fce0:ffffff8000ef2000ffffffc00a4ffe58ffffffc0cde6e8c8ffffff80095cd000
[867.148843]fd00:ffffffc00a4ffe20ffffff800813b2b4000000000000000000000055736b60f0
[867.148846]fd20:00000000000000030000007fb096c8c400000000400000000000000000000015
[867.148849]fd40:000000000000011d0000000000000111ffffff8008ef2000ffffffc0cdc44380
[867.148851]fd60:0000000000000000000000000002c098ffffffc00a4ffe20ffffff8008f00000
[867.148854]fd80:000000000000000000000055736b60f0ffffffc000000064ffffff8000000072
[867.148857]fda0:ffffff800000006effffff800000003fffffff800000012400000000024000c0
[867.148860]fdc0:ffff81b400000030000003e80000000100000000000003e8000000000002c098
[867.148862]fde0:00000000633eccfc000000000000000000000000000000000000000000000000
[867.148865]fe00:0000000000000000000000000000000000000000000000000000000000000000
[867.148868]fe20:0000000000000000ffffff8008082f70000000000000000000000040ee9ae000
[867.148871]fe40:ffffffffffffffff00000000000000010000000000000002ffffff800bea0000
[867.148874]fe60:000000000002c098ffffff800becb9d8ffffff800becb8d0ffffff800beb7748
[867.148876]fe80:000000000000300000000000000030d800000000000000000000000000000000
[867.148879]fea0:00000000000004780000001a0000001900000000000000090000000000000004
[867.148882]fec0:000000000000000300000055736b60f000000000000000000000000000000003
[867.148884]fee0:0000000000000000000000000000021800000000000000010000000000000001
[867.148887]ff00:0000000000000111000000000000000300000002000000020000000000000000
[867.148890]ff20:00000000000010f0000000000000000000000000000000000000000000000040
[867.148892]ff40:00000055736cddb00000007fb096c8a000000000000000000000005585e6b600
[867.148895]ff60:00000055736b60f0000000000000000000000000000000000000005585e6b5d0
[867.148898]ff80:00000055736b2ef8000000000000000000000000000000000000000000000000
[867.148901]ffa0:00000000000000000000007fdbea3bd000000055736abdc00000007fdbea3bd0
[867.148903]ffc0:0000007fb096c8c4000000004000000000000000000000030000000000000111
[867.148906]ffe0:0000000000000000000000000000000000000000000000000000000000000000
[867.148907]Calltrace:
[867.148911]Exceptionstack(0xffffffc00a4ffa70to0xffffffc00a4ffba0)
[867.148913]fa60:ffffff8000ef00000000008000000000
[867.148916]fa80:ffffffc00a4ffc40ffffff8000ef0024ffffff80097c02f80000000000000002
[867.148918]faa0:ffffffc00a4ffac0000000020001b57c00000000000000000000000100000000
[867.148921]fac0:ffffffc00a4ffb60ffffff800810d674ffffffc00a4ffbc0ffffff8000ef1024
[867.148924]fae0:ffffffc0cdce10c0ffffff80095b78600000000000000000ffffff8000ef2050
[867.148927]fb00:0000000000000001ffffffc0cde6e88000000000000000000000000019760817
[867.148929]fb20:000000000000000700000000000000070000000000000001ffffffc0f7f24b38
[867.148932]fb40:0000000000000022ffffff80096280b0ffffff8008463c3c0000000005f5e0ff
[867.148935]fb60:ffffff80097bfa9f00000000fffffffe0000000000000030000000000000000a
[867.148937]fb80:00000000000224d60000000000000000ffffff800813b2040000007fb096c8a0
[867.148944][]init_oopsdemo+0x24/0x38[oops_module]
[867.148953][]do_one_initcall+0x78/0x194
[867.148958][]do_init_module+0x64/0x1c0
[867.148962][]load_module+0x199c/0x1ed0
[867.148964][]SyS_finit_module+0xb0/0xbc
[867.148968][]el0_svc_naked+0x24/0x28
[867.148972]Code:95ca7426d2800000528102e172a32ec1(b9000001)
[867.148975]---[endtrace1983a52768236533]---

[867.140514]UnabletohandlekernelNULLpointerdereferenceatvirtualaddress00000000

這里能夠簡(jiǎn)要的告訴是什么問(wèn)題觸發(fā)了oops，顯然是由于訪問(wèn)非法地址00000000異常。如果是由代碼直接調(diào)用BUG()/BUG_ON()一類(lèi)的，還能給出源代碼中觸發(fā)的行號(hào)。

[867.141279]pgd=ffffffc0f0a65000
[867.141582][00000000]*pgd=0000000000000000,*pud=0000000000000000

pgd，pud試圖訪問(wèn)的地址的頁(yè)表信息，本例中為0。

[867.142164]Internalerror:Oops:96000045[#1]SMP

96000045表示錯(cuò)誤碼。后面[]內(nèi)的數(shù)值是與頁(yè)面有關(guān)的oops信息被顯示的次數(shù)。之后顯示內(nèi)核的重要特性SMP和PREEMPT被顯示的配置情況。這條信息所在的內(nèi)核啟用了SMP支持，所以只顯示SMP。

96000045這種錯(cuò)誤碼我也是第一次見(jiàn)，內(nèi)核中也沒(méi)找到。一般見(jiàn)的最多的就是001，002這種形式的？有大佬知道原因的可以評(píng)論下。

Oops的錯(cuò)誤代碼根據(jù)錯(cuò)誤的原因會(huì)有不同的定義，如果發(fā)現(xiàn)自己遇到的Oops和下面無(wú)法對(duì)應(yīng)的話，最好去內(nèi)核代碼里查找：

* error_code:* bit 0 == 0 means no page found, 1 means protection fault* bit 1 == 0 means read, 1 means write* bit 2 == 0 means kernel, 1 means user-mode* bit 3 == 0 means data, 1 means instruction

[867.142592]Moduleslinkedin:oops_module(O+)[lastunloaded:hello_module]

Modules linked in為加載了的模塊列表，hello_module為上次加載的模塊。

[867.143006]CPU:4PID:1163Comm:insmodTainted:GO4.4.194+#7
[867.143649]Hardwarename:Firefly-RK3399Board(LinuxOpensource)(DT)
[867.144236]task:ffffffc0cdc44380task.stack:ffffffc00a4fc000

CPU后的數(shù)字是錯(cuò)誤所在邏輯CPU的編號(hào)，PID表示正在運(yùn)行的進(jìn)程ID1511，內(nèi)核污染原因(G)，內(nèi)核版本( 4.4.194)。

內(nèi)核污染原因包括私有驅(qū)動(dòng)加載(P)，模塊強(qiáng)制加載(F)，模塊強(qiáng)制卸載(R),機(jī)器檢查異常發(fā)生(M)，檢測(cè)到錯(cuò)誤頁(yè)(B)等。

如果涉及到了某項(xiàng)原因，就會(huì)顯示為T(mén)ainted: G PF R這樣。如果不存在問(wèn)題，就會(huì)顯示為Not Tainted。

其中Tainted的表示可以從內(nèi)核中 kernel/panic.c 中找到：

Hardware name表示硬件平臺(tái)的名稱(chēng)。

task表示當(dāng)前進(jìn)程的地址， task.stack表示當(dāng)前進(jìn)程棧的地址。

[867.144761]PCisatinit_oopsdemo+0x24/0x38[oops_module]
[867.145247]LRisatinit_oopsdemo+0x18/0x38[oops_module]
[867.145732]pc:[]lr:[]pstate:40000145
[867.146386]sp:ffffffc00a4ffc40

init_oopsdemo+0x24/0x38[oops_module]表示錯(cuò)誤發(fā)生的地址是oops_module中的init_oopsdemo函數(shù)的第44個(gè)字節(jié)，0x38表示init_oopsdemo函數(shù)的大小。

第3行，第4行分別是PC,LR,SP寄存器的具體地址。

[867.146688]x29:ffffffc00a4ffc40x28:ffffff80081376d0
[867.147178]x27:0000000000000001x26:ffffffc0cde6e880
[867.147491]x25:0000000000000001x24:ffffff8000ef2050
[867.147495]x23:0000000000000000x22:ffffff80095b7860
[867.147498]x21:ffffffc0cdce10c0x20:ffffff80095b7860
[867.147501]x19:ffffff8000ef0000x18:ffffff80897bfa97
[867.147504]x17:0000007fb096c8a0x16:ffffff800813b204Segmentationfau
lt
[867.147508]x15:0000000000000000root@firefly:~/mx14:00000000000224d6nt/module#
[867.147511]x13:000000000000000ax12:0000000000000030
[867.147515]x11:00000000fffffffex10:ffffff80097bfa9f
[867.147518]x9:0000000005f5e0ffx8:ffffff8008463c3c
[867.147522]x7:ffffff80096280b0x6:0000000000000022
[867.147525]x5:ffffffc0f7f24b38x4:0000000000000001
[867.147528]x3:0000000000000007x2:0000000000000007
[867.147534]x1:0000000019760817x0:0000000000000000
[867.147536]
[867.147536]PC:0xffffff8000eeffa4:
[867.147550]ffa4****************************************************************
[867.147561]ffc4****************************************************************
[867.147572]ffe4********************************************************a9bf7bfd
[867.147581]0004910003fdaa1e03e0d503201f5800010095ca7426d2800000528102e172a32ec1
[867.147590]0024b9000001a8c17bfdd65f03c000ef1024ffffff80a9bf7bfd910003fdaa1e03e0
[867.147599]0044d503201f5800008095ca7418a8c17bfdd65f03c000ef1038ffffff8000000000
[867.147607]00640000000000000000000000000000000000000000000000000000000000000000
[867.147616]00840000000000000000000000000000000000000000000000000000000000000000
[867.147618]
[867.147618]LR:0xffffff8000eeff98:
[867.147629]ff98****************************************************************
[867.147639]ffb8****************************************************************
[867.147650]ffd8****************************************************************
[867.147659]fff8****************a9bf7bfd910003fdaa1e03e0d503201f5800010095ca7426
[867.147668]0018d2800000528102e172a32ec1b9000001a8c17bfdd65f03c000ef1024ffffff80
[867.147677]0038a9bf7bfd910003fdaa1e03e0d503201f5800008095ca7418a8c17bfdd65f03c0
[867.147685]005800ef1038ffffff80000000000000000000000000000000000000000000000000
[867.147693]00780000000000000000000000000000000000000000000000000000000000000000
[867.147695]
[867.147695]SP:0xffffffc00a4ffbc0:
[867.147705]fbc0095b7860ffffff80000000000000000000ef2050ffffff800000000100000000
[867.147713]fbe0cde6e880ffffffc00000000100000000081376d0ffffff800a4ffc40ffffffc0
[867.147726]fc0000ef0018ffffff800a4ffc40ffffffc000ef0024ffffff804000014500000000
[867.147734]fc20ee9ae0000000004000012ffb0000000000000000000000800000000000000000
[867.147743]fc400a4ffc50ffffffc0080830f8ffffff800a4ffcd0ffffffc00818d2d0ffffff80
[867.147765]fc6000ef2000ffffff80095cd000ffffff80cde6e8c8ffffffc0cdce1140ffffffc0
[867.147774]fc8000000000000000000818d2a4ffffff8000ef2000ffffff80095cd000ffffff80
[867.147782]fca0cde6e8c8ffffffc0095cd000ffffff80000000000000000000ef2050ffffff80
[867.147785]
[867.147785]X5:0xffffffc0f7f24ab8:
[867.147794]4ab80000003f000000000000003f0000000000000000000000000000000000000000
[867.147803]4ad80000000000000000000000000000000000000000000000000000000000000000
[867.147811]4af80000000000000000000000000000000000000000000000000000000000000000
[867.147819]4b18afbe53560000000100000000000000000810d62cffffff800000000100000000
[867.147828]4b38000000070000000000000000000000000810dd18ffffff800000000000000000
[867.147836]4b580000000001400000000000000000e29300000000000000000000000000000000
[867.147845]4b780000000000000000d591d591dead4eadffffffff00000000ffffffffffffffff
[867.147853]4b9800000000000000000008a70b000000010008a701000000010000000d00000000
[867.147855]
[867.147855]X7:0xffffff8009628030:
[867.147863]8030f26a3900ffffffc0000000000000000000000000000000000011000000000000
[867.147872]8050000f000000000000000000000000000000040000000000000008000000000000
[867.147880]80700000000000000000000000000000000000000001000000000000000000000000
[867.147889]80900000000000000001000000000000000100000002000000010000000100000000
[867.147897]80b000000000000000000927e623ffffff8004e804e8dead4eadffffffff00000000
[867.147905]80d0fffffffffffffffff2000000ffffffc000040000000000000000000100000000
[867.147914]80f000000000dead4eadffffffff00000000ffffffffffffffff09628108ffffff80
[867.147922]811009628108ffffff80000000000000000000000000000000000000000000000000
[867.147924]
[867.147924]X8:0xffffff8008463bbc:
[867.147933]3bbc9400054aaa1303e09400055452800000a94153f3f94013f5a8c37bfdd65f03c0
[867.147942]3bdcf940041317fffff6f940081317fffff4f9400c1317fffff2128002a017fffff5
[867.147950]3bfc71001c1f54000161f9405ce0f9400c00b4000140a9bf7bfdaa0603e2aa0403e1
[867.147959]3c1c910003fd940004cea8c17bfdd65f03c0128002a0d65f03c012800160d65f03c0
[867.147967]3c3ca9bb7bfd7100081f910003fda9025bf5aa0403f6a90153f3aa0603f5a90363f7
[867.147975]3c5cf9405cf354000181f9400660b4000a202a1503e2aa1603e19400047d52800000
[867.147984]3c7ca94153f3a9425bf5a94363f7a8c57bfdd65f03c071000c1f54000061f9400a60
[867.147992]3c9c17fffff371001c1f54000061f9400e6017ffffef35000820510004207100041f
[867.147994]
[867.147994]X10:0xffffff80097bfa1f:
[867.148003]fa1c0000000000000000000000000000000000000000000000000000000000000000
[867.148011]fa3c0000000000000000000000000000000000000000000000000000000000000000
[867.148020]fa5c0000000000000000000000000000000000000000000000000000000000000000
[867.148028]fa7c000000000000000000000000000000000000000000000001000000003820205b
[867.148037]fa9c312e37363934373478205d31203a353230303030303030303030303031303030
[867.148045]fabc5d3e342020726c203c5b203a6666666630386666666530303831303070205d3e
[867.148054]fadc7461747334203a65303030300a353431303030300a303030742f0a67296d0a78
[867.148062]fafc3028202c0a2973203331200a3a34353a762033346973726537206e6f2e35332e
[867.148071]fb1c2e34383135722e3132412820617453206e6f69745032502f5746202930204449
[867.148074]
[867.148074]X16:0xffffff800813b184:
[867.148083]b184fa4130029a9f87e2b4000202aa1303e2aa1403e1aa1503e0940e73e9b5000220
[867.148093]b1a4943672e08b1302b58b130294eb1302f754fffde152800002aa1603e1910163a0
[867.148101]b1c497fff7ff17ffffc6aa1303e252800001aa1503e0940e775aaa1303e017fffff0
[867.148110]b1e4f9402fa094021fc6128001a017ffffbc128000e017ffffba1280016017ffffb8
[867.148118]b204a9b67bfd910003fda90153f3f90013f5aa0003f5aa1e03e0aa0103f4aa0203f3
[867.148127]b224d503201fa903ffbfa904ffbfa905ffbfa906ffbfa907ffbfa908ffbff9004fbf
[867.148135]b24497ffefb2340000c093407c00a94153f3f94013f5a8ca7bfdd65f03c0f000b220
[867.148143]b264913d0000910aa00079404401361000e1d00088a12a1303e4aa1403e32a1503e2
[867.148146]
[867.148146]X18:0xffffff80897bfa17:
[867.148157]fa14****************************************************************
[867.148167]fa34****************************************************************
[867.148178]fa54****************************************************************
[867.148189]fa74****************************************************************
[867.148199]fa94****************************************************************
[867.148210]fab4****************************************************************
[867.148221]fad4****************************************************************
[867.148232]faf4****************************************************************
[867.148243]fb14****************************************************************
[867.148244]
[867.148244]X19:0xffffff8000eeff80:
[867.148256]ff80****************************************************************
[867.148271]ffa0****************************************************************
[867.148282]ffc0****************************************************************
[867.148293]ffe0****************************************************************
[867.148303]0000a9bf7bfd910003fdaa1e03e0d503201f5800010095ca7426d2800000528102e1
[867.148311]002072a32ec1b9000001a8c17bfdd65f03c000ef1024ffffff80a9bf7bfd910003fd
[867.148320]0040aa1e03e0d503201f5800008095ca7418a8c17bfdd65f03c000ef1038ffffff80
[867.148328]00600000000000000000000000000000000000000000000000000000000000000000
[867.148330]
[867.148330]X20:0xffffff80095b77e0:
[867.148338]77e00000000000000000000000000000000000000000000000000000000000000000
[867.148346]78000000000000000000000000000000000000000000000000000000000000000000
[867.148355]78200000000000000000000000000000000000000000000000000000000000000000
[867.148363]78400000000000000000000000000000000000000000000000000000000000000000
[867.148372]7860095b7860ffffff80095b7860ffffff80000000010000000000005dc000000000
[867.148380]788000000009756e694c000000780000000000000000000000000000000000000000
[867.148388]78a00000000000000000000000000000000000000000000000000000000000000000
[867.148397]78c00000000072696600796c66650000000000000000000000000000000000000000
[867.148398]
[867.148398]X21:0xffffffc0cdce1040:
[867.148407]1040746f6e2e6e672e6575622e752d646c6900006469dead000000000200dead0000
[867.148415]1060000000010000000000000000000000000000000000000000055aab5600000000
[867.148424]1080cdce1bc0ffffffc0cde6d909ffffffc0cde6d888ffffffc0cdce1bc8ffffffc0
[867.148433]10a00000000000000000000003dd6c62010e6c6b63612e747369666e6f6300000000
[867.148441]10c0cdce1080ffffffc06d6564736f5b206f5f73706f75646f6d005d656c00000000
[867.148449]10e000000000000000000000000f2e2e020200000000000000000000000000000000
[867.148458]11000000000000000000000000000000000000000000000000000000000000000000
[867.148466]11200000000000000000000000000000000000000000000000000000000000000000
[867.148468]
[867.148468]X22:0xffffff80095b77e0:
[867.148476]77e00000000000000000000000000000000000000000000000000000000000000000
[867.148484]78000000000000000000000000000000000000000000000000000000000000000000
[867.148493]78200000000000000000000000000000000000000000000000000000000000000000
[867.148501]78400000000000000000000000000000000000000000000000000000000000000000
[867.148510]7860095b7860ffffff80095b7860ffffff80000000010000000000005dc000000000
[867.148518]788000000009756e694c000000780000000000000000000000000000000000000000
[867.148526]78a00000000000000000000000000000000000000000000000000000000000000000
[867.148535]78c00000000072696600796c66650000000000000000000000000000000000000000
[867.148536]
[867.148536]X24:0xffffff8000ef1fd0:
[867.148545]1fd00000000000000000000000000000000000000000000000000000000000000000
[867.148553]1ff0000000000000000000000000000000000000000100000000095cd3a0ffffff80
[867.148562]2010095cd3a0ffffff8073706f6f646f6d5f00656c75000000000000000000000000
[867.148570]20300000000000000000000000000000000000000000000000000000000000000000
[867.148578]2050f089a080ffffffc0f26add00ffffffc0f2117e88ffffffc0f26add28ffffffc0
[867.148588]2070f26add00ffffffc0095c4c08ffffff80dbb66f78ffffffc00000000300000007
[867.148596]209000ef2000ffffff80000000000000000000000000000000000000000000000000
[867.148605]20b0f2f99c00ffffffc000000000000000000000000000000000f089ab40ffffffc0
[867.148606]
[867.148606]X26:0xffffffc0cde6e800:
[867.148615]e8000000000100000000d11d71a8ffffffc000000000000000000000000000000000
[867.148623]e820cf2e6030ffffffc000000000000000000000046d00000000095c42c8ffffff80
[867.148632]e8400000000000000000f7ec5e68ffffffc000000000000000000000000000000000
[867.148640]e8600000000000000000000000000000000000000000000000000000000000000000
[867.148649]e880f106a880ffffffc00000000100000000f089aa40ffffffc00000012400000000
[867.148657]e8a0000000240000000000ef1000ffffff80081375b0ffffff800000000000000000
[867.148665]e8c00000000000000000000000000000000000000000000000000000000000000000
[867.148674]e8e00000000000000000000000000000000000000000000000000000000000000000
[867.148675]
[867.148675]X28:0xffffff8008137650:
[867.148684]7650a90153f3aa0103f4aa0203f3aa1e03e0d503201ff0008f21913a1c21f9402280
[867.148693]7670b941d802aa1303e0940eb71d93407c00a94153f3a8c27bfdd65f03c0a9be7bfd
[867.148701]7690910003fda90153f3aa0103f4aa0203f3aa1e03e0d503201ff0008f21913a1c21
[867.148710]76b0f9402280b9418802aa1303e0940eb70c93407c00a94153f3a8c27bfdd65f03c0
[867.148718]76d0a9be7bfd910003fda90153f3aa0003f4aa0203f3aa1e03e0d503201faa1303e0
[867.148727]76f0b0008b61f940228291068021940eb6fc93407c00a94153f3a8c27bfdd65f03c0
[867.148735]7710a9be7bfd910003fda90153f3aa0003f3aa0103f4aa1e03e0d503201f52801801
[867.148743]7730aa1403e072a048019401c11af9006260a94153f3a8c27bfdd65f03c0a9be7bfd
[867.148745]
[867.148745]X29:0xffffffc00a4ffbc0:
[867.148754]fbc0095b7860ffffff80000000000000000000ef2050ffffff800000000100000000
[867.148763]fbe0cde6e880ffffffc00000000100000000081376d0ffffff800a4ffc40ffffffc0
[867.148771]fc0000ef0018ffffff800a4ffc40ffffffc000ef0024ffffff804000014500000000
[867.148780]fc20ee9ae0000000004000012ffb0000000000000000000000800000000000000000
[867.148790]fc400a4ffc50ffffffc0080830f8ffffff800a4ffcd0ffffffc00818d2d0ffffff80
[867.148798]fc6000ef2000ffffff80095cd000ffffff80cde6e8c8ffffffc0cdce1140ffffffc0
[867.148807]fc8000000000000000000818d2a4ffffff8000ef2000ffffff80095cd000ffffff80
[867.148815]fca0cde6e8c8ffffffc0095cd000ffffff80000000000000000000ef2050ffffff80
[867.148816]

上面打印出的這些都是異常發(fā)生時(shí)寄存器的值。

PC:PC也叫計(jì)數(shù)寄存器，用于存放下一條要執(zhí)行的指令的地址，因此在子程序返回后，要將LR中的地址存入PC，即mov PC LR。

LR:子程序的返回地址：從子程序返回后，主程序繼續(xù)執(zhí)行的指令的地址稱(chēng)為子程序的返回地址.LR也叫鏈接寄存器，用于存放子程序的返回地址。在要進(jìn)入子程序之前，先將子程序的返回地址存入LR

SP:SP也叫堆棧寄存器，用于存放要執(zhí)行的數(shù)據(jù)。

X0~X7：傳遞子程序的參數(shù)和返回值，使用時(shí)不需要保存，多余的參數(shù)用堆棧傳遞，64位的返回結(jié)果保存在x0中。

X8：用于保存子程序的返回地址，使用時(shí)不需要保存。

X9~X15：臨時(shí)寄存器，也叫可變寄存器，子程序使用時(shí)不需要保存。

X16~X17：子程序內(nèi)部調(diào)用寄存器（IPx），使用時(shí)不需要保存，盡量不要使用。

X18：平臺(tái)寄存器，它的使用與平臺(tái)相關(guān)，盡量不要使用。

X19~X28：臨時(shí)寄存器，子程序使用時(shí)必須保存。

X29：幀指針寄存器（FP），用于連接棧幀，使用時(shí)必須保存。

X30：鏈接寄存器（LR），用于保存子程序的返回地址。

X31：堆棧指針寄存器（SP），用于指向每個(gè)函數(shù)的棧頂。

[867.148820]Processinsmod(pid:1163,stacklimit=0xffffffc00a4fc000)
[867.148822]Stack:(0xffffffc00a4ffc40to0xffffffc00a500000)
[867.148826]fc40:ffffffc00a4ffc50ffffff80080830f8ffffffc00a4ffcd0ffffff800818d2d0
[867.148829]fc60:ffffff8000ef2000ffffff80095cd000ffffffc0cde6e8c8ffffffc0cdce1140
[867.148832]fc80:0000000000000000ffffff800818d2a4ffffff8000ef2000ffffff80095cd000
[867.148834]fca0:ffffffc0cde6e8c8ffffff80095cd0000000000000000000ffffff8000ef2050
[867.148837]fcc0:0000000000000001ffffffc0cde6e880ffffffc00a4ffd00ffffff800813ab5c
[867.148840]fce0:ffffff8000ef2000ffffffc00a4ffe58ffffffc0cde6e8c8ffffff80095cd000
[867.148843]fd00:ffffffc00a4ffe20ffffff800813b2b4000000000000000000000055736b60f0
[867.148846]fd20:00000000000000030000007fb096c8c400000000400000000000000000000015
[867.148849]fd40:000000000000011d0000000000000111ffffff8008ef2000ffffffc0cdc44380
[867.148851]fd60:0000000000000000000000000002c098ffffffc00a4ffe20ffffff8008f00000
[867.148854]fd80:000000000000000000000055736b60f0ffffffc000000064ffffff8000000072
[867.148857]fda0:ffffff800000006effffff800000003fffffff800000012400000000024000c0
[867.148860]fdc0:ffff81b400000030000003e80000000100000000000003e8000000000002c098
[867.148862]fde0:00000000633eccfc000000000000000000000000000000000000000000000000
[867.148865]fe00:0000000000000000000000000000000000000000000000000000000000000000
[867.148868]fe20:0000000000000000ffffff8008082f70000000000000000000000040ee9ae000
[867.148871]fe40:ffffffffffffffff00000000000000010000000000000002ffffff800bea0000
[867.148874]fe60:000000000002c098ffffff800becb9d8ffffff800becb8d0ffffff800beb7748
[867.148876]fe80:000000000000300000000000000030d800000000000000000000000000000000
[867.148879]fea0:00000000000004780000001a0000001900000000000000090000000000000004
[867.148882]fec0:000000000000000300000055736b60f000000000000000000000000000000003
[867.148884]fee0:0000000000000000000000000000021800000000000000010000000000000001
[867.148887]ff00:0000000000000111000000000000000300000002000000020000000000000000
[867.148890]ff20:00000000000010f0000000000000000000000000000000000000000000000040
[867.148892]ff40:00000055736cddb00000007fb096c8a000000000000000000000005585e6b600
[867.148895]ff60:00000055736b60f0000000000000000000000000000000000000005585e6b5d0
[867.148898]ff80:00000055736b2ef8000000000000000000000000000000000000000000000000
[867.148901]ffa0:00000000000000000000007fdbea3bd000000055736abdc00000007fdbea3bd0
[867.148903]ffc0:0000007fb096c8c4000000004000000000000000000000030000000000000111
[867.148906]ffe0:0000000000000000000000000000000000000000000000000000000000000000

stack limit顯示的大小為kstack內(nèi)核選項(xiàng)指定的大小。Stack 是棧開(kāi)頭部分的值。

[867.148907]Calltrace:
[867.148911]Exceptionstack(0xffffffc00a4ffa70to0xffffffc00a4ffba0)
[867.148913]fa60:ffffff8000ef00000000008000000000
[867.148916]fa80:ffffffc00a4ffc40ffffff8000ef0024ffffff80097c02f80000000000000002
[867.148918]faa0:ffffffc00a4ffac0000000020001b57c00000000000000000000000100000000
[867.148921]fac0:ffffffc00a4ffb60ffffff800810d674ffffffc00a4ffbc0ffffff8000ef1024
[867.148924]fae0:ffffffc0cdce10c0ffffff80095b78600000000000000000ffffff8000ef2050
[867.148927]fb00:0000000000000001ffffffc0cde6e88000000000000000000000000019760817
[867.148929]fb20:000000000000000700000000000000070000000000000001ffffffc0f7f24b38
[867.148932]fb40:0000000000000022ffffff80096280b0ffffff8008463c3c0000000005f5e0ff
[867.148935]fb60:ffffff80097bfa9f00000000fffffffe0000000000000030000000000000000a
[867.148937]fb80:00000000000224d60000000000000000ffffff800813b2040000007fb096c8a0
[867.148944][]init_oopsdemo+0x24/0x38[oops_module]
[867.148953][]do_one_initcall+0x78/0x194
[867.148958][]do_init_module+0x64/0x1c0
[867.148962][]load_module+0x199c/0x1ed0
[867.148964][]SyS_finit_module+0xb0/0xbc
[867.148968][]el0_svc_naked+0x24/0x28

棧回溯信息,可以從中看出函數(shù)調(diào)用關(guān)系

[867.148972]Code:95ca7426d2800000528102e172a32ec1(b9000001)
[867.148975]---[endtrace1983a52768236533]---
Segmentationfault

code是錯(cuò)誤發(fā)生時(shí)PC指向的地址處的開(kāi)頭20字節(jié)的代碼，括號(hào)里的是出錯(cuò)的具體指令。

如何根據(jù)OOPS找出bug

確定出錯(cuò)位置在內(nèi)核函數(shù)還是驅(qū)動(dòng)

System.map文件記錄了所有符號(hào)的運(yùn)行地址,這里的符號(hào)可以理解成函數(shù)名和變量。

System.map一般在內(nèi)核編譯完成后，根目錄下生成。

0000000000000000A__rela_size
0000000000000000A_kernel_flags_le_hi32
0000000000000000A_kernel_offset_le_hi32
0000000000000000A_kernel_size_le_hi32
000000000000000aA_kernel_flags_le_lo32
0000000000000200APECOFF_FILE_ALIGNMENT
0000000000080000A_kernel_offset_le_lo32
000000000159e638A__rela_offset
0000000001800000A_kernel_size_le_lo32
ffffff8008080000t_head
ffffff8008080000T_text
ffffff8008080800T__exception_text_start
ffffff8008080800T_stext
ffffff8008080800Tdo_undefinstr
ffffff8008080a18Tdo_sysinstr
ffffff8008080ab4Tdo_mem_abort
ffffff8008080b60Tdo_sp_pc_abort
ffffff8008080c34Tdo_debug_exceptio
.............
ffffff8009879a48b__key.30413
ffffff8009879a48b__key.30416
ffffff8009879a48b__key.48814
ffffff8009879a48b__key.48818
ffffff8009879a48b__key.48819
ffffff8009879a48b__key.48820
ffffff8009879a48b__key.48821
ffffff800987a000Bidmap_pg_dir
ffffff800987d000Bswapper_pg_dir
ffffff800987f000Btramp_pg_dir
ffffff8009880000B_end

System.map中內(nèi)核函數(shù)的范圍是：ffffff8008080000 ~ ffffff8009880000。而PC出錯(cuò)的位置是ffffff8000ef0024。

所以，可以判定不是內(nèi)核函數(shù)出錯(cuò)引起的，而是某個(gè)驅(qū)動(dòng)模塊。

如果把oops_module.ko直接編譯進(jìn)ko中，就是內(nèi)核引起的錯(cuò)誤了。PC出錯(cuò)時(shí)的地址也會(huì)剛好在System.map中。

反匯編驅(qū)動(dòng)文件

而OOPS信息也告訴我們，錯(cuò)誤是出在了init_oopsdemo。

[17981.657899]PCisatinit_oopsdemo+0x24/0x38[oops_module]
[17981.658385]LRisatinit_oopsdemo+0x18/0x38[oops_module]

那如果OOPS沒(méi)有打印出出錯(cuò)驅(qū)動(dòng)的名字呢？

我們可以使用 cat /proc/kallsyms > kallsyms.txt命令，在kallsyms.txt中找出與PC值接近的符號(hào)。kallsyms.txt內(nèi)容如下。

ffffff8008080800Tdo_undefinstr
ffffff8008080800T_stext
ffffff8008080800T__exception_text_start
ffffff8008080a18Tdo_sysinstr
ffffff8008080ab4Tdo_mem_abort
ffffff8008080b60Tdo_sp_pc_abort
ffffff8008080c34Tdo_debug_exception
.........
ffffff80094cfc0cTsparse_mem_map_populate
ffffff80094cfc64T_einittext
0000000000000000aoops_module.c[oops_module]
ffffff8000ef0000t$x[oops_module]
ffffff8000ef0000tinit_oopsdemo[oops_module]
ffffff8000ef0030t$d[oops_module]
ffffff8000ef0038t$x[oops_module]
ffffff8000ef0038tcleanup_oopsdemo[oops_module]
ffffff8000ef0058t$d[oops_module]
ffffff800bee40c8?__UNIQUE_ID_license2[oops_module]
ffffff800bee40d4?__UNIQUE_ID_author1[oops_module]
ffffff800bee40e3?__UNIQUE_ID_license0[oops_module]
ffffff800befb368n$d[oops_module]
0000000000000000aoops_module.mod.c[oops_module]
ffffff8000ef2000d$d[oops_module]
ffffff800bee40f8?$d[oops_module]
ffffff800bee40f8?__module_depends[oops_module]
ffffff800bee4101?__UNIQUE_ID_vermagic0[oops_module]
ffffff8000ef2000d__this_module[oops_module]
ffffff8000ef0038tcleanup_module[oops_module]
ffffff8000ef0000tinit_module[oops_module]
ffffff800818d0acuprintk[oops_module]
ffffff800808e770u_mcount[oops_module]

從上面可以看出，PC的值和ffffff8000ef0058很接近。所以，基本可以確定出錯(cuò)的模塊是oops_module。而這個(gè)模塊正是我自己寫(xiě)的例程。

接下來(lái)，我們就要準(zhǔn)備反匯編oops_module.ko了，根據(jù)反匯編可以進(jìn)一步確認(rèn)出錯(cuò)的行數(shù)。

aarch64-linux-gnu-objdump-Doops_module.ko>oops_module.dis

oops_module.dis 內(nèi)容如下

oops_module.ko:fileformatelf64-littleaarch64


Disassemblyofsection.note.gnu.build-id:

0000000000000000<.note.gnu.build-id>:
0:00000004.inst0x00000004;undefined
4:00000014.inst0x00000014;undefined
8:00000003.inst0x00000003;undefined
c:00554e47.inst0x00554e47;undefined
10:70d55614adrx20,fffffffffffaaad3<__UNIQUE_ID_vermagic0+0xfffffffffffaaa9a>
14:56a7eb64.inst0x56a7eb64;undefined
18:a66fbdf8.inst0xa66fbdf8;undefined
1c:2b31c03fcmnw1,w17,sxtw
20:bd9e1ffe.inst0xbd9e1ffe;undefined

Disassemblyofsection.text:

0000000000000000:
0:a9bf7bfdstpx29,x30,[sp,#-16]!
4:910003fdmovx29,sp
8:aa1e03e0movx0,x30
c:94000000bl0<_mcount>
10:58000100ldrx0,30
14:94000000bl0
18:d2800000movx0,#0x0//#0
1c:528102e1movw1,#0x817//#2071
20:72a32ec1movkw1,#0x1976,lsl#16
24:b9000001strw1,[x0]
28:a8c17bfdldpx29,x30,[sp],#16
2c:d65f03c0ret
...

0000000000000038:
38:a9bf7bfdstpx29,x30,[sp,#-16]!
3c:910003fdmovx29,sp
40:aa1e03e0movx0,x30
44:94000000bl0<_mcount>
48:58000080ldrx0,58
4c:94000000bl0
50:a8c17bfdldpx29,x30,[sp],#16
54:d65f03c0ret
...

Disassemblyofsection.modinfo:

0000000000000000<__UNIQUE_ID_license2>:
0:6563696cfnmlsz12.h,p2/m,z11.h,z3.h
4:3d65736eldrb14,[x27,#2396]
8:004c5047.inst0x004c5047;undefined

根據(jù)反匯編和之前 PC is at init_oopsdemo+0x24/0x38 [oops_module]，可以確定發(fā)生錯(cuò)誤的是0x24的位置。

24:b9000001strw1,[x0]#將w1寄存器的值，傳送到地址值為x0的（存儲(chǔ)器）內(nèi)存中

而根據(jù)18: d2800000 mov x0, #0x0 // #0 可以確定x0 為0。

到這里也基本可以確定，是w1的值賦值給0地址時(shí)出錯(cuò)了。

其他方法

gdb

?oops_moduleaarch64-linux-gnu-gdb-q./oops_module.ko
Readingsymbolsfrom./oops_module.ko...done.
(gdb)list*init_oopsdemo+0x24
0x4cisininit_oopsdemo(/home/zhongyi/code/module/oops_module/oops_module.c:10).
5MODULE_AUTHOR("ZHONGYI");
6
7staticintinit_oopsdemo(void)
8{
9printk("oopsmoduleinit!
");
10*((int*)0x00)=0x19760817;
11return0;
12}
13
14module_init(init_oopsdemo);
(gdb)

addr2line

Linux下addr2line命令用于將程序指令地址轉(zhuǎn)換為所對(duì)應(yīng)的函數(shù)名、以及函數(shù)所在的源文件名和行號(hào)。當(dāng)含有調(diào)試信息(-g)的執(zhí)行程序出現(xiàn)crash時(shí)(core dumped)，可使用addr2line命令快速定位出錯(cuò)的位置。

如果無(wú)法確定文件名或函數(shù)名，addr2line將在它們的位置打印兩個(gè)問(wèn)號(hào)；如果無(wú)法確定行號(hào)，addr2line將打印0或一個(gè)問(wèn)號(hào)。

參數(shù)說(shuō)明：

-a:在函數(shù)名、文件名和行號(hào)信息之前，以十六進(jìn)制形式顯示地址。

-b:指定目標(biāo)文件的格式為bfdname。

-C:將低級(jí)別的符號(hào)名解碼為用戶級(jí)別的名字。

-e:指定需要轉(zhuǎn)換地址的可執(zhí)行文件名，默認(rèn)文件是a.out。

-f:在顯示文件名、行號(hào)信息的同時(shí)顯示函數(shù)名。

-s:僅顯示每個(gè)文件名(the base of each file name)去除目錄名。

-i:如果需要轉(zhuǎn)換的地址是一個(gè)內(nèi)聯(lián)函數(shù)，則還將打印返回第一個(gè)非內(nèi)聯(lián)函數(shù)的信息。

-j:讀取指定section的偏移而不是絕對(duì)地址。

-p:使打印更加人性化：每個(gè)地址(location)的信息都打印在一行上。

-r:啟用或禁用遞歸量限制。

--help:打印幫助信息。

--version:打印版本號(hào)。

?oops_moduleaarch64-linux-gnu-addr2line-e./oops_module.ko-p-f0x24
init_oopsdemoat/home/zhongyi/code/module/oops_module/oops_module.c:10
?oops_modulecat/home/zhongyi/code/module/oops_module/oops_module.c|tail-n+5|head-n10
MODULE_AUTHOR("ZHONGYI");

staticintinit_oopsdemo(void)
{
printk("oopsmoduleinit!
");
*((int*)0x00)=0x19760817;
return0;
}

module_init(init_oopsdemo);

decodecode

在linux內(nèi)核里面有很多腳本工具，位于linux/scripts/，里面有一個(gè)decodecode工具可以用來(lái)轉(zhuǎn)換機(jī)器碼，decodecode腳本可以在沒(méi)有源代碼或符號(hào)表的情況下，將oops異常的log作為輸入就可以解析出錯(cuò)誤位置的匯編代碼。

oops_log.txt內(nèi)容如下

calltrace:
[867.148911]Exceptionstack(0xffffffc00a4ffa70to0xffffffc00a4ffba0)
[867.148913]fa60:ffffff8000ef00000000008000000000
[867.148916]fa80:ffffffc00a4ffc40ffffff8000ef0024ffffff80097c02f80000000000000002
[867.148918]faa0:ffffffc00a4ffac0000000020001b57c00000000000000000000000100000000
[867.148921]fac0:ffffffc00a4ffb60ffffff800810d674ffffffc00a4ffbc0ffffff8000ef1024
[867.148924]fae0:ffffffc0cdce10c0ffffff80095b78600000000000000000ffffff8000ef2050
[867.148927]fb00:0000000000000001ffffffc0cde6e88000000000000000000000000019760817
[867.148929]fb20:000000000000000700000000000000070000000000000001ffffffc0f7f24b38
[867.148932]fb40:0000000000000022ffffff80096280b0ffffff8008463c3c0000000005f5e0ff
[867.148935]fb60:ffffff80097bfa9f00000000fffffffe0000000000000030000000000000000a
[867.148937]fb80:00000000000224d60000000000000000ffffff800813b2040000007fb096c8a0
[867.148944][]init_oopsdemo+0x24/0x38[oops_module]
[867.148953][]do_one_initcall+0x78/0x194
[867.148958][]do_init_module+0x64/0x1c0
[867.148962][]load_module+0x199c/0x1ed0
[867.148964][]SyS_finit_module+0xb0/0xbc
[867.148968][]el0_svc_naked+0x24/0x2

$ARCH=arm64CROSS_COMPILE=/home/zhongyi/code/rk3399_linux_release_v2.5.1_20210301/prebuilts/gcc/linux-x86/aarch64/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu-./scripts/decodecode

	

	執(zhí)行腳本后，就可以得到出錯(cuò)的匯編代碼。trapping instruction指出了出錯(cuò)的地址。根據(jù)oop_module.ko的反匯編可以知道出錯(cuò)的位置24: b9000001 str w1, [x0]。

	注意：腳本認(rèn)為該機(jī)器碼是跟host結(jié)構(gòu)相同的原生機(jī)器碼，想要跨架構(gòu)翻譯要指定架構(gòu)和交叉工具鏈。

	faddr2line

	內(nèi)核開(kāi)發(fā)者為了方便問(wèn)題的排查，也經(jīng)常需要根據(jù)內(nèi)核棧，快速定位導(dǎo)致問(wèn)題發(fā)生的代碼位置。所以，Linux 內(nèi)核維護(hù)了一個(gè) faddr2line 腳本，根據(jù)函數(shù)名+偏移量輸出源碼文件名和行號(hào)。

	在使用這個(gè)腳本之前，還需要注意兩個(gè)前提條件：

	第一，帶有調(diào)試信息的內(nèi)核文件，一般名字為 vmlinux（注意，/boot 目錄下面的 vmlinz 是壓縮后的內(nèi)核，不可以直接拿來(lái)使用）。

	第二，系統(tǒng)中需要安裝 awk、readelf、addr2line、size、nm 等命令。

	對(duì)于第二個(gè)條件，這些命令都包含在 binutils 軟件包中，只需要執(zhí)行 apt 或者 dnf 命令安裝即可。

	而對(duì)第一個(gè)條件中的內(nèi)核調(diào)試信息，各個(gè)主要的發(fā)行版也都提供了相應(yīng)的軟件倉(cāng)庫(kù)，你可以根據(jù)文檔進(jìn)行安裝。比如，對(duì)于 Ubuntu 來(lái)說(shuō)，你可以執(zhí)行下面的命令安裝調(diào)試信息：

	
codename=$(lsb_release-cs)
sudotee/etc/apt/sources.list.d/ddebs.list<

	

	由于我們這里的oops 是發(fā)生在ko中，而不是內(nèi)核。因此，使用faddr2line指定oops_module.ko 即可。

	
?kernelgit:(firefly)?scripts/faddr2line/home/zhongyi/code/module/oops_module/oops_module.koinit_oopsdemo+0x24
init_oopsdemo+0x24/0x30:
init_oopsdemoat/home/zhongyi/code/module/oops_module/oops_module.c:18


	

	如果oops發(fā)生在內(nèi)核中，將oops_module.ko 換成對(duì)應(yīng)的vmlinux即可。

	最后，貼下oops_module.c的源代碼，感興趣的大家可以自己寫(xiě)一個(gè)分析下。

	
#include
#include

MODULE_LICENSE("BSD/GPL");
MODULE_AUTHOR("ZHONGYI");

staticintinit_oopsdemo(void)
{
printk("oopsmoduleinit!
");
*((int*)0x00)=0x19760817;
return0;
}

module_init(init_oopsdemo);

staticvoidcleanup_oopsdemo(void)
{
printk("oopsmoduleexit!
");
}

module_exit(cleanup_oopsdemo);
MODULE_LICENSE("GPL");


	

	審核編輯：湯梓紅