内核堆栈怎么看（查看内核的符号信息）
804的十六进制是多少 如何解读内核的oops
OOPS信息解读
root@firefly:~/mnt/module# in od oops_module.ko [ 867.140514] Unable to handle kernel NULL pointer dereference at virtual address 00000000[ 867.141279] pgd = ffffffc0f0a65000[ 867.141582] [00000000] pgd=0000000000000000, pud=0000000000000000[ 867.142164] Internal error: Oops: 96000045 [#1] P[ 867.142592] Modules linked in: oops_module(O+)[ 867.143006] CPU: 4 PID: 1163 Comm: in od Tainted: G O 4.4.194+ #7[ 867.143649] Hardware name: Firefly-RK3399 Board (Linux Opensource) (DT)[ 867.144236] task: ffffffc0cdc44380 task.stack: ffffffc00a4fc000[ 867.144761] PC is at init_oopsdemo+0x24/0x38 [oops_module][ 867.145247] LR is at init_oopsdemo+0x18/0x38 [oops_module][ 867.145732] pc : [ltffffff8000ef0024gt] lr : [ltffffff8000ef0018gt] pstate: 40000145[ 867.146386] sp : ffffffc00a4ffc40[ 867.146688] x29: ffffffc00a4ffc40 x28: ffffff80081376d0 [ 867.147178] x27: 0000000000000001 x26: ffffffc0cde6e880 [ 867.147491] x25: 0000000000000001 x24: ffffff8000ef2050 [ 867.147495] x23: 0000000000000000 x22: ffffff80095b7860 [ 867.147498] x21: ffffffc0cdce10c0 x20: ffffff80095b7860 [ 867.147501] x19: ffffff8000ef0000 x18: ffffff80897bfa97 [ 867.147504] x17: 0000007fb096c8a0 x16: ffffff800813b204 Segmentation fault[ 867.147508] x15: 0000000000000000 root@firefly:~/mx14: 00000000000224d6 nt/module# [ 867.147511] x13: 000000000000000a x12: 0000000000000030 [ 867.147515] x11: 00000000fffffffe x10: ffffff80097bfa9f [ 867.147518] x9 : 0000000005f5e0ff x8 : ffffff8008463c3c [ 867.147522] x7 : ffffff80096280b0 x6 : 0000000000000022 [ 867.147525] x5 : ffffffc0f7f24b38 x4 : 0000000000000001 [ 867.147528] x3 : 0000000000000007 x2 : 0000000000000007 [ 867.147534] x1 : 0000000019760817 x0 : 0000000000000000 [ 867.147536] [ 867.147536] PC: 0xffffff8000eeffa4:[ 867.147550] ffa4 [ 867.147561] ffc4 [ 867.147572] ffe4 a9bf7bfd[ 867.147581] 0004 910003fd aa1e03e0 d503201f 58000100 95ca7426 d2800000 528102e1 72a32ec1[ 867.147590] 0024 b9000001 a8c17bfd d65f03c0 00ef1024 ffffff80 a9bf7bfd 910003fd aa1e03e0[ 867.147599] 0044 d503201f 58000080 95ca7418 a8c17bfd d65f03c0 00ef1038 ffffff80 00000000[ 867.147607] 0064 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147616] 0084 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147618] [ 867.147618] LR: 0xffffff8000eeff98:[ 867.147629] ff98 [ 867.147639] ffb8 [ 867.147650] ffd8 [ 867.147659] fff8 a9bf7bfd 910003fd aa1e03e0 d503201f 58000100 95ca7426[ 867.147668] 0018 d2800000 528102e1 72a32ec1 b9000001 a8c17bfd d65f03c0 00ef1024 ffffff80[ 867.147677] 0038 a9bf7bfd 910003fd aa1e03e0 d503201f 58000080 95ca7418 a8c17bfd d65f03c0[ 867.147685] 0058 00ef1038 ffffff80 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147693] 0078 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147695] [ 867.147695] SP: 0xffffffc00a4ffbc0:[ 867.147705] fbc0 095b7860 ffffff80 00000000 00000000 00ef2050 ffffff80 00000001 00000000[ 867.147713] fbe0 cde6e880 ffffffc0 00000001 00000000 081376d0 ffffff80 0a4ffc40 ffffffc0[ 867.147726] fc00 00ef0018 ffffff80 0a4ffc40 ffffffc0 00ef0024 ffffff80 40000145 00000000[ 867.147734] fc20 ee9ae000 00000040 00012ffb 00000000 00000000 00000080 00000000 00000000[ 867.147743] fc40 0a4ffc50 ffffffc0 080830f8 ffffff80 0a4ffcd0 ffffffc0 0818d2d0 ffffff80[ 867.147765] fc60 00ef2000 ffffff80 095cd000 ffffff80 cde6e8c8 ffffffc0 cdce1140 ffffffc0[ 867.147774] fc80 00000000 00000000 0818d2a4 ffffff80 00ef2000 ffffff80 095cd000 ffffff80[ 867.147782] fca0 cde6e8c8 ffffffc0 095cd000 ffffff80 00000000 00000000 00ef2050 ffffff80[ 867.147785] [ 867.147785] X5: 0xffffffc0f7f24ab8:[ 867.147794] 4ab8 0000003f 00000000 0000003f 00000000 00000000 00000000 00000000 00000000[ 867.147803] 4ad8 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147811] 4af8 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147819] 4b18 afbe5356 00000001 00000000 00000000 0810d62c ffffff80 00000001 00000000[ 867.147828] 4b38 00000007 00000000 00000000 00000000 0810dd18 ffffff80 00000000 00000000[ 867.147836] 4b58 00000000 01400000 00000000 0000e293 00000000 00000000 00000000 00000000[ 867.147845] 4b78 00000000 00000000 d591d591 dead4ead ffffffff 00000000 ffffffff ffffffff[ 867.147853] 4b98 00000000 00000000 0008a70b 00000001 0008a701 00000001 0000000d 00000000[ 867.147855] [ 867.147855] X7: 0xffffff8009628030:[ 867.147863] 8030 f26a3900 ffffffc0 00000000 00000000 00000000 00000000 00110000 00000000[ 867.147872] 8050 000f0000 00000000 00000000 00000000 00040000 00000000 00080000 00000000[ 867.147880] 8070 00000000 00000000 00000000 00000000 00000001 00000000 00000000 00000000[ 867.147889] 8090 00000000 00000001 00000000 00000001 00000002 00000001 00000001 00000000[ 867.147897] 80b0 00000000 00000000 0927e623 ffffff80 04e804e8 dead4ead ffffffff 00000000[ 867.147905] 80d0 ffffffff ffffffff f2000000 ffffffc0 00040000 00000000 00000001 00000000[ 867.147914] 80f0 00000000 dead4ead ffffffff 00000000 ffffffff ffffffff 09628108 ffffff80[ 867.147922] 8110 09628108 ffffff80 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147924] [ 867.147924] X8: 0xffffff8008463bbc:[ 867.147933] 3bbc 9400054a aa1303e0 94000554 52800000 a94153f3 f94013f5 a8c37bfd d65f03c0[ 867.147942] 3bdc f9400413 17fffff6 f9400813 17fffff4 f9400c13 17fffff2 128002a0 17fffff5[ 867.147950] 3bfc 71001c1f 54000161 f9405ce0 f9400c00 b4000140 a9bf7bfd aa0603e2 aa0403e1[ 867.147959] 3c1c 910003fd 940004ce a8c17bfd d65f03c0 128002a0 d65f03c0 12800160 d65f03c0[ 867.147967] 3c3c a9bb7bfd 7100081f 910003fd a9025bf5 aa0403f6 a90153f3 aa0603f5 a90363f7[ 867.147975] 3c5c f9405cf3 54000181 f9400660 b4000a20 2a1503e2 aa1603e1 9400047d 52800000[ 867.147984] 3c7c a94153f3 a9425bf5 a94363f7 a8c57bfd d65f03c0 71000c1f 54000061 f9400a60[ 867.147992] 3c9c 17fffff3 71001c1f 54000061 f9400e60 17ffffef 35000820 51000420 7100041f[ 867.147994] [ 867.147994] X10: 0xffffff80097bfa1f:[ 867.148003] fa1c 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148011] fa3c 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148020] fa5c 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148028] fa7c 00000000 00000000 00000000 00000000 00000000 00000001 00000000 3820205b[ 867.148037] fa9c 312e3736 39343734 78205d31 203a3532 30303030 30303030 30303030 31303030[ 867.148045] fabc 5d3e3420 20726c20 3c5b203a 66666666 30386666 66653030 38313030 70205d3e[ 867.148054] fadc 74617473 34203a65 30303030 0a353431 30303030 0a303030 742f0a67 296d0a78[ 867.148062] fafc 3028202c 0a297320 3331200a 3a34353a 76203334 69737265 37206e6f 2e35332e[ 867.148071] fb1c 2e343831 35722e31 32412820 61745320 6e6f6974 5032502f 57462029 30204449[ 867.148074] [ 867.148074] X16: 0xffffff800813b184:[ 867.148083] b184 fa413002 9a9f87e2 b4000202 aa1303e2 aa1403e1 aa1503e0 940e73e9 b5000220[ 867.148093] b1a4 943672e0 8b1302b5 8b130294 eb1302f7 54fffde1 52800002 aa1603e1 910163a0[ 867.148101] b1c4 97fff7ff 17ffffc6 aa1303e2 52800001 aa1503e0 940e775a aa1303e0 17fffff0[ 867.148110] b1e4 f9402fa0 94021fc6 128001a0 17ffffbc 128000e0 17ffffba 12800160 17ffffb8[ 867.148118] b204 a9b67bfd 910003fd a90153f3 f90013f5 aa0003f5 aa1e03e0 aa0103f4 aa0203f3[ 867.148127] b224 d503201f a903ffbf a904ffbf a905ffbf a906ffbf a907ffbf a908ffbf f9004fbf[ 867.148135] b244 97ffefb2 340000c0 93407c00 a94153f3 f94013f5 a8ca7bfd d65f03c0 f000b220[ 867.148143] b264 913d0000 910aa000 79404401 361000e1 d00088a1 2a1303e4 aa1403e3 2a1503e2[ 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] 0000 a9bf7bfd 910003fd aa1e03e0 d503201f 58000100 95ca7426 d2800000 528102e1[ 867.148311] 0020 72a32ec1 b9000001 a8c17bfd d65f03c0 00ef1024 ffffff80 a9bf7bfd 910003fd[ 867.148320] 0040 aa1e03e0 d503201f 58000080 95ca7418 a8c17bfd d65f03c0 00ef1038 ffffff80[ 867.148328] 0060 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148330] [ 867.148330] X20: 0xffffff80095b77e0:[ 867.148338] 77e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148346] 7800 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148355] 7820 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148363] 7840 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148372] 7860 095b7860 ffffff80 095b7860 ffffff80 00000001 00000000 00005dc0 00000000[ 867.148380] 7880 00000009 756e694c 00000078 00000000 00000000 00000000 00000000 00000000[ 867.148388] 78a0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148397] 78c0 00000000 72696600 796c6665 00000000 00000000 00000000 00000000 00000000[ 867.148398] [ 867.148398] X21: 0xffffffc0cdce1040:[ 867.148407] 1040 746f6e2e 6e672e65 75622e75 2d646c69 00006469 dead0000 00000200 dead0000[ 867.148415] 1060 00000001 00000000 00000000 00000000 00000000 00000000 055aab56 00000000[ 867.148424] 1080 cdce1bc0 ffffffc0 cde6d909 ffffffc0 cde6d888 ffffffc0 cdce1bc8 ffffffc0[ 867.148433] 10a0 00000000 00000000 000003dd 6c62010e 6c6b6361 2e747369 666e6f63 00000000[ 867.148441] 10c0 cdce1080 ffffffc0 6d656473 6f5b206f 5f73706f 75646f6d 005d656c 00000000[ 867.148449] 10e0 00000000 00000000 0000000f 2e2e0202 00000000 00000000 00000000 00000000[ 867.148458] 1100 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148466] 1120 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148468] [ 867.148468] X22: 0xffffff80095b77e0:[ 867.148476] 77e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148484] 7800 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148493] 7820 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148501] 7840 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148510] 7860 095b7860 ffffff80 095b7860 ffffff80 00000001 00000000 00005dc0 00000000[ 867.148518] 7880 00000009 756e694c 00000078 00000000 00000000 00000000 00000000 00000000[ 867.148526] 78a0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148535] 78c0 00000000 72696600 796c6665 00000000 00000000 00000000 00000000 00000000[ 867.148536] [ 867.148536] X24: 0xffffff8000ef1fd0:[ 867.148545] 1fd0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148553] 1ff0 00000000 00000000 00000000 00000000 00000001 00000000 095cd3a0 ffffff80[ 867.148562] 2010 095cd3a0 ffffff80 73706f6f 646f6d5f 00656c75 00000000 00000000 00000000[ 867.148570] 2030 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148578] 2050 f089a080 ffffffc0 f26add00 ffffffc0 f2117e88 ffffffc0 f26add28 ffffffc0[ 867.148588] 2070 f26add00 ffffffc0 095c4c08 ffffff80 dbb66f78 ffffffc0 00000003 00000007[ 867.148596] 2090 00ef2000 ffffff80 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148605] 20b0 f2f99c00 ffffffc0 00000000 00000000 00000000 00000000 f089ab40 ffffffc0[ 867.148606] [ 867.148606] X26: 0xffffffc0cde6e800:[ 867.148615] e800 00000001 00000000 d11d71a8 ffffffc0 00000000 00000000 00000000 00000000[ 867.148623] e820 cf2e6030 ffffffc0 00000000 00000000 0000046d 00000000 095c42c8 ffffff80[ 867.148632] e840 00000000 00000000 f7ec5e68 ffffffc0 00000000 00000000 00000000 00000000[ 867.148640] e860 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148649] e880 f106a880 ffffffc0 00000001 00000000 f089aa40 ffffffc0 00000124 00000000[ 867.148657] e8a0 00000024 00000000 00ef1000 ffffff80 081375b0 ffffff80 00000000 00000000[ 867.148665] e8c0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148674] e8e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148675] [ 867.148675] X28: 0xffffff8008137650:[ 867.148684] 7650 a90153f3 aa0103f4 aa0203f3 aa1e03e0 d503201f f0008f21 913a1c21 f9402280[ 867.148693] 7670 b941d802 aa1303e0 940eb71d 93407c00 a94153f3 a8c27bfd d65f03c0 a9be7bfd[ 867.148701] 7690 910003fd a90153f3 aa0103f4 aa0203f3 aa1e03e0 d503201f f0008f21 913a1c21[ 867.148710] 76b0 f9402280 b9418802 aa1303e0 940eb70c 93407c00 a94153f3 a8c27bfd d65f03c0[ 867.148718] 76d0 a9be7bfd 910003fd a90153f3 aa0003f4 aa0203f3 aa1e03e0 d503201f aa1303e0[ 867.148727] 76f0 b0008b61 f9402282 91068021 940eb6fc 93407c00 a94153f3 a8c27bfd d65f03c0[ 867.148735] 7710 a9be7bfd 910003fd a90153f3 aa0003f3 aa0103f4 aa1e03e0 d503201f 52801801[ 867.148743] 7730 aa1403e0 72a04801 9401c11a f9006260 a94153f3 a8c27bfd d65f03c0 a9be7bfd[ 867.148745] [ 867.148745] X29: 0xffffffc00a4ffbc0:[ 867.148754] fbc0 095b7860 ffffff80 00000000 00000000 00ef2050 ffffff80 00000001 00000000[ 867.148763] fbe0 cde6e880 ffffffc0 00000001 00000000 081376d0 ffffff80 0a4ffc40 ffffffc0[ 867.148771] fc00 00ef0018 ffffff80 0a4ffc40 ffffffc0 00ef0024 ffffff80 40000145 00000000[ 867.148780] fc20 ee9ae000 00000040 00012ffb 00000000 00000000 00000080 00000000 00000000[ 867.148790] fc40 0a4ffc50 ffffffc0 080830f8 ffffff80 0a4ffcd0 ffffffc0 0818d2d0 ffffff80[ 867.148798] fc60 00ef2000 ffffff80 095cd000 ffffff80 cde6e8c8 ffffffc0 cdce1140 ffffffc0[ 867.148807] fc80 00000000 00000000 0818d2a4 ffffff80 00ef2000 ffffff80 095cd000 ffffff80[ 867.148815] fca0 cde6e8c8 ffffffc0 095cd000 ffffff80 00000000 00000000 00ef2050 ffffff80[ 867.148816] [ 867.148820] Process in od (pid: 1163, stack limit = 0xffffffc00a4fc000)[ 867.148822] Stack: (0xffffffc00a4ffc40 to 0xffffffc00a500000)[ 867.148826] fc40: ffffffc00a4ffc50 ffffff80080830f8 ffffffc00a4ffcd0 ffffff800818d2d0[ 867.148829] fc60: ffffff8000ef2000 ffffff80095cd000 ffffffc0cde6e8c8 ffffffc0cdce1140[ 867.148832] fc80: 0000000000000000 ffffff800818d2a4 ffffff8000ef2000 ffffff80095cd000[ 867.148834] fca0: ffffffc0cde6e8c8 ffffff80095cd000 0000000000000000 ffffff8000ef2050[ 867.148837] fcc0: 0000000000000001 ffffffc0cde6e880 ffffffc00a4ffd00 ffffff800813ab5c[ 867.148840] fce0: ffffff8000ef2000 ffffffc00a4ffe58 ffffffc0cde6e8c8 ffffff80095cd000[ 867.148843] fd00: ffffffc00a4ffe20 ffffff800813b2b4 0000000000000000 00000055736b60f0[ 867.148846] fd20: 0000000000000003 0000007fb096c8c4 0000000040000000 0000000000000015[ 867.148849] fd40: 000000000000011d 0000000000000111 ffffff8008ef2000 ffffffc0cdc44380[ 867.148851] fd60: 0000000000000000 000000000002c098 ffffffc00a4ffe20 ffffff8008f00000[ 867.148854] fd80: 0000000000000000 00000055736b60f0 ffffffc000000064 ffffff8000000072[ 867.148857] fda0: ffffff800000006e ffffff800000003f ffffff8000000124 00000000024000c0[ 867.148860] fdc0: ffff81b400000030 000003e800000001 00000000000003e8 000000000002c098[ 867.148862] fde0: 00000000633eccfc 0000000000000000 0000000000000000 0000000000000000[ 867.148865] fe00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000[ 867.148868] fe20: 0000000000000000 ffffff8008082f70 0000000000000000 00000040ee9ae000[ 867.148871] fe40: ffffffffffffffff 0000000000000001 0000000000000002 ffffff800bea0000[ 867.148874] fe60: 000000000002c098 ffffff800becb9d8 ffffff800becb8d0 ffffff800beb7748[ 867.148876] fe80: 0000000000003000 00000000000030d8 0000000000000000 0000000000000000[ 867.148879] fea0: 0000000000000478 0000001a00000019 0000000000000009 0000000000000004[ 867.148882] fec0: 0000000000000003 00000055736b60f0 0000000000000000 0000000000000003[ 867.148884] fee0: 0000000000000000 0000000000000218 0000000000000001 0000000000000001[ 867.148887] ff00: 0000000000000111 0000000000000003 0000000200000002 0000000000000000[ 867.148890] ff20: 00000000000010f0 0000000000000000 0000000000000000 0000000000000040[ 867.148892] ff40: 00000055736cddb0 0000007fb096c8a0 0000000000000000 0000005585e6b600[ 867.148895] ff60: 00000055736b60f0 0000000000000000 0000000000000000 0000005585e6b5d0[ 867.148898] ff80: 00000055736b2ef8 0000000000000000 0000000000000000 0000000000000000[ 867.148901] ffa0: 0000000000000000 0000007fdbea3bd0 00000055736abdc0 0000007fdbea3bd0[ 867.148903] ffc0: 0000007fb096c8c4 0000000040000000 0000000000000003 0000000000000111[ 867.148906] ffe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000[ 867.148907] Call trace:[ 867.148911] Exception stack(0xffffffc00a4ffa70 to 0xffffffc00a4ffba0)[ 867.148913] fa60: ffffff8000ef0000 0000008000000000[ 867.148916] fa80: ffffffc00a4ffc40 ffffff8000ef0024 ffffff80097c02f8 0000000000000002[ 867.148918] faa0: ffffffc00a4ffac0 000000020001b57c 0000000000000000 0000000100000000[ 867.148921] fac0: ffffffc00a4ffb60 ffffff800810d674 ffffffc00a4ffbc0 ffffff8000ef1024[ 867.148924] fae0: ffffffc0cdce10c0 ffffff80095b7860 0000000000000000 ffffff8000ef2050[ 867.148927] fb00: 0000000000000001 ffffffc0cde6e880 0000000000000000 0000000019760817[ 867.148929] fb20: 0000000000000007 0000000000000007 0000000000000001 ffffffc0f7f24b38[ 867.148932] fb40: 0000000000000022 ffffff80096280b0 ffffff8008463c3c 0000000005f5e0ff[ 867.148935] fb60: ffffff80097bfa9f 00000000fffffffe 0000000000000030 000000000000000a[ 867.148937] fb80: 00000000000224d6 0000000000000000 ffffff800813b204 0000007fb096c8a0[ 867.148944] [ltffffff8000ef0024gt] init_oopsdemo+0x24/0x38 [oops_module][ 867.148953] [ltffffff80080830f8gt] do_one_initcall+0x78/0x194[ 867.148958] [ltffffff800818d2d0gt] do_init_module+0x64/0x1c0[ 867.148962] [ltffffff800813ab5cgt] load_module+0x199c/0x1ed0[ 867.148964] [ltffffff800813b2b4gt] SyS_finit_module+0xb0/0xbc[ 867.148968] [ltffffff8008082f70gt] el0_svc_naked+0x24/0x28[ 867.148972] Code: 95ca7426 d2800000 528102e1 72a32ec1 (b9000001) [ 867.148975] ---[ end trace 1983a52768236533 ]---
[ 867.140514] Unable to handle kernel NULL pointer dereference at virtual address 00000000
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这里能够简要的告诉是什么问题触发了oops，显然是由于访问非法地址00000000异常。如果是由代码直接调用BUG()/BUG_ON()一类的，还能给出源代码中触发的行号。
[ 867.141279] pgd = ffffffc0f0a65000[ 867.141582] [00000000] pgd=0000000000000000, pud=0000000000000000
pgd，pud试图访问的地址的页表信息，本例中为0。
[ 867.142164] Internal error: Oops: 96000045 [#1] P
96000045表示错误码。后面[]内的数值是与页面有关的oops信息被显示的次数。之后显示内核的重要特性 P和PREEMPT被显示的配置情况。这条信息所在的内核启用了 P支持，所以只显示 P。
96000045这种错误码我也是之一次见，内核中也没找到。一般见的最多的就是001，002这种形式的？有大佬知道原因的可以评论下。
Oops的错误代码根据错误的原因会有不同的定义，如果发现自己遇到的Oops和下面无法对应的话，更好去内核代码里查找
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] Modules linked in: oops_module(O+) [last unloaded: hello_module]
Modules linked in为加载了的模块列表，hello_module为上次加载的模块。
[ 867.143006] CPU: 4 PID: 1163 Comm: in od Tainted: G O 4.4.194+ #7[ 867.143649] Hardware name: Firefly-RK3399 Board (Linux Opensource) (DT)[ 867.144236] task: ffffffc0cdc44380 task.stack: ffffffc00a4fc000
CPU后的数字是错误所在逻辑CPU的编号，PID表示正在运行的进程ID1511，内核污染原因(G)，内核版本( 4.4.194)。
内核污染原因包括私有驱动加载(P)，模块强制加载(F)，模块强制卸载(R),机器检查异常发生(M)，检测到错误页(B)等。
如果涉及到了某项原因，就会显示为Tainted: G PF R这样。如果不存在问题，就会显示为Not Tainted。
其中Tainted的表示可以从内核中 kernel/panic.c 中找到
Tainted描述‘G’if all modules loaded have a GPL or compatible license‘P’if any proprietary module has been loaded. Modules without a MODULE_LICENSE or with a MODULE_LICENSE that is not recognised by in od as GPL compatible are assumed to be proprietary.‘F’if any module was force loaded by “in od -f”.‘S’if the Oops occurred on an P kernel running on hardware that hasn’t been certified as safe to run multiprocessor. Currently this occurs only on various Athlons that are not P capable.‘R’if a module was force unloaded by “rmmod -f”.‘M’if any processor has reported a Machine Check Exception.‘B’if a page-release function has found a bad page reference or some unexpected page flags.‘U’if a user or user application specifically requested that the Tainted flag be set.‘D’if the kernel has died recently, i.e. there was an OOPS or BUG.‘W’if a warning has previously been issued by the kernel.‘C’if a staging module / driver has been loaded.‘I’if the kernel is working around a sever bug in the platform’s firmware (BIOS or similar).
Hardware name表示硬件平台的名称。
task表示当前进程的地址， task.stack表示当前进程栈的地址。
[ 867.144761] PC is at init_oopsdemo+0x24/0x38 [oops_module][ 867.145247] LR is at init_oopsdemo+0x18/0x38 [oops_module][ 867.145732] pc : [ltffffff8000ef0024gt] lr : [ltffffff8000ef0018gt] pstate: 40000145[ 867.146386] sp : ffffffc00a4ffc40
init_oopsdemo+0x24/0x38[oops_module]表示错误发生的地址是oops_module中的init_oopsdemo函数的第44个字节，0x38表示init_oopsdemo函数的大小。
第3行，第4行分别是PC,LR,SP寄存器的具体地址。
[ 867.146688] x29: ffffffc00a4ffc40 x28: ffffff80081376d0 [ 867.147178] x27: 0000000000000001 x26: ffffffc0cde6e880 [ 867.147491] x25: 0000000000000001 x24: ffffff8000ef2050 [ 867.147495] x23: 0000000000000000 x22: ffffff80095b7860 [ 867.147498] x21: ffffffc0cdce10c0 x20: ffffff80095b7860 [ 867.147501] x19: ffffff8000ef0000 x18: ffffff80897bfa97 [ 867.147504] x17: 0000007fb096c8a0 x16: ffffff800813b204 Segmentation fault[ 867.147508] x15: 0000000000000000 root@firefly:~/mx14: 00000000000224d6 nt/module# [ 867.147511] x13: 000000000000000a x12: 0000000000000030 [ 867.147515] x11: 00000000fffffffe x10: ffffff80097bfa9f [ 867.147518] x9 : 0000000005f5e0ff x8 : ffffff8008463c3c [ 867.147522] x7 : ffffff80096280b0 x6 : 0000000000000022 [ 867.147525] x5 : ffffffc0f7f24b38 x4 : 0000000000000001 [ 867.147528] x3 : 0000000000000007 x2 : 0000000000000007 [ 867.147534] x1 : 0000000019760817 x0 : 0000000000000000 [ 867.147536] [ 867.147536] PC: 0xffffff8000eeffa4:[ 867.147550] ffa4 [ 867.147561] ffc4 [ 867.147572] ffe4 a9bf7bfd[ 867.147581] 0004 910003fd aa1e03e0 d503201f 58000100 95ca7426 d2800000 528102e1 72a32ec1[ 867.147590] 0024 b9000001 a8c17bfd d65f03c0 00ef1024 ffffff80 a9bf7bfd 910003fd aa1e03e0[ 867.147599] 0044 d503201f 58000080 95ca7418 a8c17bfd d65f03c0 00ef1038 ffffff80 00000000[ 867.147607] 0064 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147616] 0084 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147618] [ 867.147618] LR: 0xffffff8000eeff98:[ 867.147629] ff98 [ 867.147639] ffb8 [ 867.147650] ffd8 [ 867.147659] fff8 a9bf7bfd 910003fd aa1e03e0 d503201f 58000100 95ca7426[ 867.147668] 0018 d2800000 528102e1 72a32ec1 b9000001 a8c17bfd d65f03c0 00ef1024 ffffff80[ 867.147677] 0038 a9bf7bfd 910003fd aa1e03e0 d503201f 58000080 95ca7418 a8c17bfd d65f03c0[ 867.147685] 0058 00ef1038 ffffff80 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147693] 0078 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147695] [ 867.147695] SP: 0xffffffc00a4ffbc0:[ 867.147705] fbc0 095b7860 ffffff80 00000000 00000000 00ef2050 ffffff80 00000001 00000000[ 867.147713] fbe0 cde6e880 ffffffc0 00000001 00000000 081376d0 ffffff80 0a4ffc40 ffffffc0[ 867.147726] fc00 00ef0018 ffffff80 0a4ffc40 ffffffc0 00ef0024 ffffff80 40000145 00000000[ 867.147734] fc20 ee9ae000 00000040 00012ffb 00000000 00000000 00000080 00000000 00000000[ 867.147743] fc40 0a4ffc50 ffffffc0 080830f8 ffffff80 0a4ffcd0 ffffffc0 0818d2d0 ffffff80[ 867.147765] fc60 00ef2000 ffffff80 095cd000 ffffff80 cde6e8c8 ffffffc0 cdce1140 ffffffc0[ 867.147774] fc80 00000000 00000000 0818d2a4 ffffff80 00ef2000 ffffff80 095cd000 ffffff80[ 867.147782] fca0 cde6e8c8 ffffffc0 095cd000 ffffff80 00000000 00000000 00ef2050 ffffff80[ 867.147785] [ 867.147785] X5: 0xffffffc0f7f24ab8:[ 867.147794] 4ab8 0000003f 00000000 0000003f 00000000 00000000 00000000 00000000 00000000[ 867.147803] 4ad8 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147811] 4af8 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147819] 4b18 afbe5356 00000001 00000000 00000000 0810d62c ffffff80 00000001 00000000[ 867.147828] 4b38 00000007 00000000 00000000 00000000 0810dd18 ffffff80 00000000 00000000[ 867.147836] 4b58 00000000 01400000 00000000 0000e293 00000000 00000000 00000000 00000000[ 867.147845] 4b78 00000000 00000000 d591d591 dead4ead ffffffff 00000000 ffffffff ffffffff[ 867.147853] 4b98 00000000 00000000 0008a70b 00000001 0008a701 00000001 0000000d 00000000[ 867.147855] [ 867.147855] X7: 0xffffff8009628030:[ 867.147863] 8030 f26a3900 ffffffc0 00000000 00000000 00000000 00000000 00110000 00000000[ 867.147872] 8050 000f0000 00000000 00000000 00000000 00040000 00000000 00080000 00000000[ 867.147880] 8070 00000000 00000000 00000000 00000000 00000001 00000000 00000000 00000000[ 867.147889] 8090 00000000 00000001 00000000 00000001 00000002 00000001 00000001 00000000[ 867.147897] 80b0 00000000 00000000 0927e623 ffffff80 04e804e8 dead4ead ffffffff 00000000[ 867.147905] 80d0 ffffffff ffffffff f2000000 ffffffc0 00040000 00000000 00000001 00000000[ 867.147914] 80f0 00000000 dead4ead ffffffff 00000000 ffffffff ffffffff 09628108 ffffff80[ 867.147922] 8110 09628108 ffffff80 00000000 00000000 00000000 00000000 00000000 00000000[ 867.147924] [ 867.147924] X8: 0xffffff8008463bbc:[ 867.147933] 3bbc 9400054a aa1303e0 94000554 52800000 a94153f3 f94013f5 a8c37bfd d65f03c0[ 867.147942] 3bdc f9400413 17fffff6 f9400813 17fffff4 f9400c13 17fffff2 128002a0 17fffff5[ 867.147950] 3bfc 71001c1f 54000161 f9405ce0 f9400c00 b4000140 a9bf7bfd aa0603e2 aa0403e1[ 867.147959] 3c1c 910003fd 940004ce a8c17bfd d65f03c0 128002a0 d65f03c0 12800160 d65f03c0[ 867.147967] 3c3c a9bb7bfd 7100081f 910003fd a9025bf5 aa0403f6 a90153f3 aa0603f5 a90363f7[ 867.147975] 3c5c f9405cf3 54000181 f9400660 b4000a20 2a1503e2 aa1603e1 9400047d 52800000[ 867.147984] 3c7c a94153f3 a9425bf5 a94363f7 a8c57bfd d65f03c0 71000c1f 54000061 f9400a60[ 867.147992] 3c9c 17fffff3 71001c1f 54000061 f9400e60 17ffffef 35000820 51000420 7100041f[ 867.147994] [ 867.147994] X10: 0xffffff80097bfa1f:[ 867.148003] fa1c 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148011] fa3c 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148020] fa5c 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148028] fa7c 00000000 00000000 00000000 00000000 00000000 00000001 00000000 3820205b[ 867.148037] fa9c 312e3736 39343734 78205d31 203a3532 30303030 30303030 30303030 31303030[ 867.148045] fabc 5d3e3420 20726c20 3c5b203a 66666666 30386666 66653030 38313030 70205d3e[ 867.148054] fadc 74617473 34203a65 30303030 0a353431 30303030 0a303030 742f0a67 296d0a78[ 867.148062] fafc 3028202c 0a297320 3331200a 3a34353a 76203334 69737265 37206e6f 2e35332e[ 867.148071] fb1c 2e343831 35722e31 32412820 61745320 6e6f6974 5032502f 57462029 30204449[ 867.148074] [ 867.148074] X16: 0xffffff800813b184:[ 867.148083] b184 fa413002 9a9f87e2 b4000202 aa1303e2 aa1403e1 aa1503e0 940e73e9 b5000220[ 867.148093] b1a4 943672e0 8b1302b5 8b130294 eb1302f7 54fffde1 52800002 aa1603e1 910163a0[ 867.148101] b1c4 97fff7ff 17ffffc6 aa1303e2 52800001 aa1503e0 940e775a aa1303e0 17fffff0[ 867.148110] b1e4 f9402fa0 94021fc6 128001a0 17ffffbc 128000e0 17ffffba 12800160 17ffffb8[ 867.148118] b204 a9b67bfd 910003fd a90153f3 f90013f5 aa0003f5 aa1e03e0 aa0103f4 aa0203f3[ 867.148127] b224 d503201f a903ffbf a904ffbf a905ffbf a906ffbf a907ffbf a908ffbf f9004fbf[ 867.148135] b244 97ffefb2 340000c0 93407c00 a94153f3 f94013f5 a8ca7bfd d65f03c0 f000b220[ 867.148143] b264 913d0000 910aa000 79404401 361000e1 d00088a1 2a1303e4 aa1403e3 2a1503e2[ 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] 0000 a9bf7bfd 910003fd aa1e03e0 d503201f 58000100 95ca7426 d2800000 528102e1[ 867.148311] 0020 72a32ec1 b9000001 a8c17bfd d65f03c0 00ef1024 ffffff80 a9bf7bfd 910003fd[ 867.148320] 0040 aa1e03e0 d503201f 58000080 95ca7418 a8c17bfd d65f03c0 00ef1038 ffffff80[ 867.148328] 0060 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148330] [ 867.148330] X20: 0xffffff80095b77e0:[ 867.148338] 77e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148346] 7800 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148355] 7820 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148363] 7840 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148372] 7860 095b7860 ffffff80 095b7860 ffffff80 00000001 00000000 00005dc0 00000000[ 867.148380] 7880 00000009 756e694c 00000078 00000000 00000000 00000000 00000000 00000000[ 867.148388] 78a0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148397] 78c0 00000000 72696600 796c6665 00000000 00000000 00000000 00000000 00000000[ 867.148398] [ 867.148398] X21: 0xffffffc0cdce1040:[ 867.148407] 1040 746f6e2e 6e672e65 75622e75 2d646c69 00006469 dead0000 00000200 dead0000[ 867.148415] 1060 00000001 00000000 00000000 00000000 00000000 00000000 055aab56 00000000[ 867.148424] 1080 cdce1bc0 ffffffc0 cde6d909 ffffffc0 cde6d888 ffffffc0 cdce1bc8 ffffffc0[ 867.148433] 10a0 00000000 00000000 000003dd 6c62010e 6c6b6361 2e747369 666e6f63 00000000[ 867.148441] 10c0 cdce1080 ffffffc0 6d656473 6f5b206f 5f73706f 75646f6d 005d656c 00000000[ 867.148449] 10e0 00000000 00000000 0000000f 2e2e0202 00000000 00000000 00000000 00000000[ 867.148458] 1100 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148466] 1120 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148468] [ 867.148468] X22: 0xffffff80095b77e0:[ 867.148476] 77e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148484] 7800 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148493] 7820 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148501] 7840 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148510] 7860 095b7860 ffffff80 095b7860 ffffff80 00000001 00000000 00005dc0 00000000[ 867.148518] 7880 00000009 756e694c 00000078 00000000 00000000 00000000 00000000 00000000[ 867.148526] 78a0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148535] 78c0 00000000 72696600 796c6665 00000000 00000000 00000000 00000000 00000000[ 867.148536] [ 867.148536] X24: 0xffffff8000ef1fd0:[ 867.148545] 1fd0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148553] 1ff0 00000000 00000000 00000000 00000000 00000001 00000000 095cd3a0 ffffff80[ 867.148562] 2010 095cd3a0 ffffff80 73706f6f 646f6d5f 00656c75 00000000 00000000 00000000[ 867.148570] 2030 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148578] 2050 f089a080 ffffffc0 f26add00 ffffffc0 f2117e88 ffffffc0 f26add28 ffffffc0[ 867.148588] 2070 f26add00 ffffffc0 095c4c08 ffffff80 dbb66f78 ffffffc0 00000003 00000007[ 867.148596] 2090 00ef2000 ffffff80 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148605] 20b0 f2f99c00 ffffffc0 00000000 00000000 00000000 00000000 f089ab40 ffffffc0[ 867.148606] [ 867.148606] X26: 0xffffffc0cde6e800:[ 867.148615] e800 00000001 00000000 d11d71a8 ffffffc0 00000000 00000000 00000000 00000000[ 867.148623] e820 cf2e6030 ffffffc0 00000000 00000000 0000046d 00000000 095c42c8 ffffff80[ 867.148632] e840 00000000 00000000 f7ec5e68 ffffffc0 00000000 00000000 00000000 00000000[ 867.148640] e860 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148649] e880 f106a880 ffffffc0 00000001 00000000 f089aa40 ffffffc0 00000124 00000000[ 867.148657] e8a0 00000024 00000000 00ef1000 ffffff80 081375b0 ffffff80 00000000 00000000[ 867.148665] e8c0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148674] e8e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[ 867.148675] [ 867.148675] X28: 0xffffff8008137650:[ 867.148684] 7650 a90153f3 aa0103f4 aa0203f3 aa1e03e0 d503201f f0008f21 913a1c21 f9402280[ 867.148693] 7670 b941d802 aa1303e0 940eb71d 93407c00 a94153f3 a8c27bfd d65f03c0 a9be7bfd[ 867.148701] 7690 910003fd a90153f3 aa0103f4 aa0203f3 aa1e03e0 d503201f f0008f21 913a1c21[ 867.148710] 76b0 f9402280 b9418802 aa1303e0 940eb70c 93407c00 a94153f3 a8c27bfd d65f03c0[ 867.148718] 76d0 a9be7bfd 910003fd a90153f3 aa0003f4 aa0203f3 aa1e03e0 d503201f aa1303e0[ 867.148727] 76f0 b0008b61 f9402282 91068021 940eb6fc 93407c00 a94153f3 a8c27bfd d65f03c0[ 867.148735] 7710 a9be7bfd 910003fd a90153f3 aa0003f3 aa0103f4 aa1e03e0 d503201f 52801801[ 867.148743] 7730 aa1403e0 72a04801 9401c11a f9006260 a94153f3 a8c27bfd d65f03c0 a9be7bfd[ 867.148745] [ 867.148745] X29: 0xffffffc00a4ffbc0:[ 867.148754] fbc0 095b7860 ffffff80 00000000 00000000 00ef2050 ffffff80 00000001 00000000[ 867.148763] fbe0 cde6e880 ffffffc0 00000001 00000000 081376d0 ffffff80 0a4ffc40 ffffffc0[ 867.148771] fc00 00ef0018 ffffff80 0a4ffc40 ffffffc0 00ef0024 ffffff80 40000145 00000000[ 867.148780] fc20 ee9ae000 00000040 00012ffb 00000000 00000000 00000080 00000000 00000000[ 867.148790] fc40 0a4ffc50 ffffffc0 080830f8 ffffff80 0a4ffcd0 ffffffc0 0818d2d0 ffffff80[ 867.148798] fc60 00ef2000 ffffff80 095cd000 ffffff80 cde6e8c8 ffffffc0 cdce1140 ffffffc0[ 867.148807] fc80 00000000 00000000 0818d2a4 ffffff80 00ef2000 ffffff80 095cd000 ffffff80[ 867.148815] fca0 cde6e8c8 ffffffc0 095cd000 ffffff80 00000000 00000000 00ef2050 ffffff80[ 867.148816]
上面打印出的这些都是异常发生时寄存器的值。
PC:PC也叫计数寄存器，用于存放下一条要执行的指令的地址，在子程序返回后，要将LR中的地址存入PC，即mov PC LR。
LR:子程序的返回地址从子程序返回后，主程序继续执行的指令的地址称为子程序的返回地址.LR也叫链接寄存器，用于存放子程序的返回地址。在要进入子程序之前，先将子程序的返回地址存入LR
SP:SP也叫堆栈寄存器，用于存放要执行的数据。
X0~X7传递子程序的参数和返回值，使用时不需要保存，多余的参数用堆栈传递，64位的返回结果保存在x0中。
X8用于保存子程序的返回地址，使用时不需要保存。
X9~X15临时寄存器，也叫可变寄存器，子程序使用时不需要保存。
X16~X17子程序内部调用寄存器（IPx），使用时不需要保存，尽量不要使用。
X18平台寄存器，它的使用与平台相关，尽量不要使用。
X19~X28临时寄存器，子程序使用时必须保存。
X29帧指针寄存器（FP），用于连接栈帧，使用时必须保存。
X30链接寄存器（LR），用于保存子程序的返回地址。
X31堆栈指针寄存器（SP），用于指向每个函数的栈顶。
[ 867.148820] Process in od (pid: 1163, stack limit = 0xffffffc00a4fc000)[ 867.148822] Stack: (0xffffffc00a4ffc40 to 0xffffffc00a500000)[ 867.148826] fc40: ffffffc00a4ffc50 ffffff80080830f8 ffffffc00a4ffcd0 ffffff800818d2d0[ 867.148829] fc60: ffffff8000ef2000 ffffff80095cd000 ffffffc0cde6e8c8 ffffffc0cdce1140[ 867.148832] fc80: 0000000000000000 ffffff800818d2a4 ffffff8000ef2000 ffffff80095cd000[ 867.148834] fca0: ffffffc0cde6e8c8 ffffff80095cd000 0000000000000000 ffffff8000ef2050[ 867.148837] fcc0: 0000000000000001 ffffffc0cde6e880 ffffffc00a4ffd00 ffffff800813ab5c[ 867.148840] fce0: ffffff8000ef2000 ffffffc00a4ffe58 ffffffc0cde6e8c8 ffffff80095cd000[ 867.148843] fd00: ffffffc00a4ffe20 ffffff800813b2b4 0000000000000000 00000055736b60f0[ 867.148846] fd20: 0000000000000003 0000007fb096c8c4 0000000040000000 0000000000000015[ 867.148849] fd40: 000000000000011d 0000000000000111 ffffff8008ef2000 ffffffc0cdc44380[ 867.148851] fd60: 0000000000000000 000000000002c098 ffffffc00a4ffe20 ffffff8008f00000[ 867.148854] fd80: 0000000000000000 00000055736b60f0 ffffffc000000064 ffffff8000000072[ 867.148857] fda0: ffffff800000006e ffffff800000003f ffffff8000000124 00000000024000c0[ 867.148860] fdc0: ffff81b400000030 000003e800000001 00000000000003e8 000000000002c098[ 867.148862] fde0: 00000000633eccfc 0000000000000000 0000000000000000 0000000000000000[ 867.148865] fe00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000[ 867.148868] fe20: 0000000000000000 ffffff8008082f70 0000000000000000 00000040ee9ae000[ 867.148871] fe40: ffffffffffffffff 0000000000000001 0000000000000002 ffffff800bea0000[ 867.148874] fe60: 000000000002c098 ffffff800becb9d8 ffffff800becb8d0 ffffff800beb7748[ 867.148876] fe80: 0000000000003000 00000000000030d8 0000000000000000 0000000000000000[ 867.148879] fea0: 0000000000000478 0000001a00000019 0000000000000009 0000000000000004[ 867.148882] fec0: 0000000000000003 00000055736b60f0 0000000000000000 0000000000000003[ 867.148884] fee0: 0000000000000000 0000000000000218 0000000000000001 0000000000000001[ 867.148887] ff00: 0000000000000111 0000000000000003 0000000200000002 0000000000000000[ 867.148890] ff20: 00000000000010f0 0000000000000000 0000000000000000 0000000000000040[ 867.148892] ff40: 00000055736cddb0 0000007fb096c8a0 0000000000000000 0000005585e6b600[ 867.148895] ff60: 00000055736b60f0 0000000000000000 0000000000000000 0000005585e6b5d0[ 867.148898] ff80: 00000055736b2ef8 0000000000000000 0000000000000000 0000000000000000[ 867.148901] ffa0: 0000000000000000 0000007fdbea3bd0 00000055736abdc0 0000007fdbea3bd0[ 867.148903] ffc0: 0000007fb096c8c4 0000000040000000 0000000000000003 0000000000000111[ 867.148906] ffe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
stack limit显示的大小为kstack内核选项指定的大小。Stack 是栈开头部分的值。
[ 867.148907] Call trace:[ 867.148911] Exception stack(0xffffffc00a4ffa70 to 0xffffffc00a4ffba0)[ 867.148913] fa60: ffffff8000ef0000 0000008000000000[ 867.148916] fa80: ffffffc00a4ffc40 ffffff8000ef0024 ffffff80097c02f8 0000000000000002[ 867.148918] faa0: ffffffc00a4ffac0 000000020001b57c 0000000000000000 0000000100000000[ 867.148921] fac0: ffffffc00a4ffb60 ffffff800810d674 ffffffc00a4ffbc0 ffffff8000ef1024[ 867.148924] fae0: ffffffc0cdce10c0 ffffff80095b7860 0000000000000000 ffffff8000ef2050[ 867.148927] fb00: 0000000000000001 ffffffc0cde6e880 0000000000000000 0000000019760817[ 867.148929] fb20: 0000000000000007 0000000000000007 0000000000000001 ffffffc0f7f24b38[ 867.148932] fb40: 0000000000000022 ffffff80096280b0 ffffff8008463c3c 0000000005f5e0ff[ 867.148935] fb60: ffffff80097bfa9f 00000000fffffffe 0000000000000030 000000000000000a[ 867.148937] fb80: 00000000000224d6 0000000000000000 ffffff800813b204 0000007fb096c8a0[ 867.148944] [ltffffff8000ef0024gt] init_oopsdemo+0x24/0x38 [oops_module][ 867.148953] [ltffffff80080830f8gt] do_one_initcall+0x78/0x194[ 867.148958] [ltffffff800818d2d0gt] do_init_module+0x64/0x1c0[ 867.148962] [ltffffff800813ab5cgt] load_module+0x199c/0x1ed0[ 867.148964] [ltffffff800813b2b4gt] SyS_finit_module+0xb0/0xbc[ 867.148968] [ltffffff8008082f70gt] el0_svc_naked+0x24/0x28
栈回溯信息,可以从中看出函数调用关系
[ 867.148972] Code: 95ca7426 d2800000 528102e1 72a32ec1 (b9000001) [ 867.148975] ---[ end trace 1983a52768236533 ]---Segmentation fault
code是错误发生时PC指向的地址处的开头20字节的代码，括号里的是出错的具体指令。
如何根据OOPS找出bug
确定出错位置在内核函数还是驱动
System.map文件记录了所有符号的运行地址,这里的符号可以理解成函数名和变量。
System.map一般在内核编译完成后，根目录下生成。
0000000000000000 A __rela_size0000000000000000 A _kernel_flags_le_hi320000000000000000 A _kernel_offset_le_hi320000000000000000 A _kernel_size_le_hi32000000000000000a A _kernel_flags_le_lo320000000000000200 A PECOFF_FILE_ALIGNMENT0000000000080000 A _kernel_offset_le_lo32000000000159e638 A __rela_offset0000000001800000 A _kernel_size_le_lo32ffffff8008080000 t _headffffff8008080000 T _textffffff8008080800 T __exception_text_startffffff8008080800 T _stextffffff8008080800 T do_undefinstrffffff8008080a18 T do_sysinstrffffff8008080ab4 T do_mem_abortffffff8008080b60 T do_sp_pc_abortffffff8008080c34 T do_debug_exceptio.............ffffff8009879a48 b __key.30413ffffff8009879a48 b __key.30416ffffff8009879a48 b __key.48814ffffff8009879a48 b __key.48818ffffff8009879a48 b __key.48819ffffff8009879a48 b __key.48820ffffff8009879a48 b __key.48821ffffff800987a000 B idmap_pg_dirffffff800987d000 B swapper_pg_dirffffff800987f000 B tr_pg_dirffffff8009880000 B _end
System.map中内核函数的范围是ffffff8008080000 ~ ffffff8009880000。而PC出错的位置是ffffff8000ef0024。
所以，可以判定不是内核函数出错引起的，而是某个驱动模块。
如果把oops_module.ko直接编译进ko中，就是内核引起的错误了。PC出错时的地址也会刚好在System.map中。
反汇编驱动文件
而OOPS信息也告诉我们，错误是出在了init_oopsdemo。
[17981.657899] PC is at init_oopsdemo+0x24/0x38 [oops_module][17981.658385] LR is at init_oopsdemo+0x18/0x38 [oops_module]
那如果OOPS没有打印出出错驱动的名字呢？
我们可以使用 cat /proc/kallsyms gt kallsyms.txt命令，在kallsyms.txt中找出与PC值接近的符号。kallsyms.txt内容如下。
ffffff8008080800 T do_undefinstrffffff8008080800 T _stextffffff8008080800 T __exception_text_startffffff8008080a18 T do_sysinstrffffff8008080ab4 T do_mem_abortffffff8008080b60 T do_sp_pc_abortffffff8008080c34 T do_debug_exception.........ffffff80094cfc0c T sparse_mem_map_populateffffff80094cfc64 T _einittext0000000000000000 a oops_module.c [oops_module]ffffff8000ef0000 t $x [oops_module]ffffff8000ef0000 t init_oopsdemo [oops_module]ffffff8000ef0030 t $d [oops_module]ffffff8000ef0038 t $x [oops_module]ffffff8000ef0038 t cleanup_oopsdemo [oops_module]ffffff8000ef0058 t $d [oops_module]ffffff800bee40c8 ? __UNIQUE_ID_license2 [oops_module]ffffff800bee40d4 ? __UNIQUE_ID_author1 [oops_module]ffffff800bee40e3 ? __UNIQUE_ID_license0 [oops_module]ffffff800befb368 n $d [oops_module]0000000000000000 a oops_module.mod.c [oops_module]ffffff8000ef2000 d $d [oops_module]ffffff800bee40f8 ? $d [oops_module]ffffff800bee40f8 ? __module_depends [oops_module]ffffff800bee4101 ? __UNIQUE_ID_vermagic0 [oops_module]ffffff8000ef2000 d __this_module [oops_module]ffffff8000ef0038 t cleanup_module [oops_module]ffffff8000ef0000 t init_module [oops_module]ffffff800818d0ac u printk [oops_module]ffffff800808e770 u _mcount [oops_module]
从上面可以看出，PC的值和ffffff8000ef0058很接近。所以，基本可以确定出错的模块是oops_module。而这个模块正是我自己写的例程。
接下来，我们就要准备反汇编oops_module.ko了，根据反汇编可以进一步确认出错的行数。
aarch64-linux-gnu-objdump -D oops_module.ko gt oops_module.dis
oops_module.dis 内容如下
oops_module.ko: file format elf64-littleaarch64Disassembly of section .note.gnu.build-id:0000000000000000 lt.note.gnu.build-idgt: 0: 00000004 .inst 0x00000004 undefined 4: 00000014 .inst 0x00000014 undefined 8: 00000003 .inst 0x00000003 undefined c: 00554e47 .inst 0x00554e47 undefined 10: 70d55614 adr x20, fffffffffffaaad3 lt__UNIQUE_ID_vermagic0+0xfffffffffffaaa9agt 14: 56a7eb64 .inst 0x56a7eb64 undefined 18: a66fbdf8 .inst 0xa66fbdf8 undefined 1c: 2b31c03f cmn w1, w17, sxtw 20: bd9e1ffe .inst 0xbd9e1ffe undefinedDisassembly of section .text:0000000000000000 ltinit_modulegt: 0: a9bf7bfd stp x29, x30, [sp, #-16]! 4: 910003fd mov x29, sp 8: aa1e03e0 mov x0, x30 c: 94000000 bl 0 lt_mcountgt 10: 58000100 ldr x0, 30 ltinit_module+0x30gt 14: 94000000 bl 0 ltprintkgt 18: d2800000 mov x0, #0x0 // #0 1c: 528102e1 mov w1, #0x817 // #2071 20: 72a32ec1 movk w1, #0x1976, lsl #16 24: b9000001 str w1, [x0] 28: a8c17bfd ldp x29, x30, [sp], #16 2c: d65f03c0 ret ... 0000000000000038 ltcleanup_modulegt: 38: a9bf7bfd stp x29, x30, [sp, #-16]! 3c: 910003fd mov x29, sp 40: aa1e03e0 mov x0, x30 44: 94000000 bl 0 lt_mcountgt 48: 58000080 ldr x0, 58 ltcleanup_module+0x20gt 4c: 94000000 bl 0 ltprintkgt 50: a8c17bfd ldp x29, x30, [sp], #16 54: d65f03c0 ret ...Disassembly of section .mod:0000000000000000 lt__UNIQUE_ID_license2gt: 0: 6563696c fnmls z12.h, p2/m, z11.h, z3.h 4: 3d65736e ldr b14, [x27, #2396] 8: 004c5047 .inst 0x004c5047 undefined
根据反汇编和之前 PC is at init_oopsdemo+0x24/0x38 [oops_module]，可以确定发生错误的是0x24的位置。
24: b9000001 str w1, [x0] #将w1寄存器的值，传送到地址值为x0的（存储器）内存中
而根据18: d2800000 mov x0, #0x0 // #0 可以确定x0 为0。
到这里也基本可以确定，是w1的值赋值给0地址时出错了。
其他
gdb
? oops_module aarch64-linux-gnu-gdb -q ./oops_module.ko Reading symbols from ./oops_module.ko...done.(gdb) list init_oopsdemo+0x240x4c is in init_oopsdemo (/home/zhongyi/code/module/oops_module/oops_module.c:10).5 MODULE_AUTHOR(#34ZHONGYI#34)67 static int init_oopsdemo(void)8 {9 printk(#34oops module init! \n#34)10 ((int)0x00) = 0x1976081711 return 012 }1314 module_init(init_oopsdemo)(gdb)
addr2line
Linux下addr2line命令用于将程序指令地址转换为所对应的函数名、以及函数所在的源文件名和行号。当含有调试信息(-g)的执行程序出现crash时(core dumped)，可使用addr2line命令快速定位出错的位置。
如果无法确定文件名或函数名，addr2line将在它们的位置打印两个问号；如果无法确定行号，addr2line将打印0或一个问号。
参数说明
-a:在函数名、文件名和行号信息之前，以十六进制形式显示地址。-b:指定目标文件的格式为bfdname。-C:将低级别的符号名解码为用户级别的名字。-e:指定需要转换地址的可执行文件名，默认文件是a.out。-f:在显示文件名、行号信息的显示函数名。-s:仅显示每个文件名(the base of each file name)去除目录名。-i:如果需要转换的地址是一个内联函数，则还将打印返回之一个非内联函数的信息。-j:读取指定section的偏移而不是绝对地址。-p:使打印更加人性化每个地址(location)的信息都打印在一行上。-r:启用或禁用递归量限制。--help:打印帮助信息。--version:打印版本号。? oops_module aarch64-linux-gnu-addr2line -e ./oops_module.ko -p -f 0x24init_oopsdemo at /home/zhongyi/code/module/oops_module/oops_module.c:10? oops_module cat /home/zhongyi/code/module/oops_module/oops_module.c | tail -n +5 | head -n 10 MODULE_AUTHOR(#34ZHONGYI#34)static int init_oopsdemo(void){ printk(#34oops module init! \n#34) ((int)0x00) = 0x19760817 return 0}module_init(init_oopsdemo)
decodecode
在linux内核里面有很多脚本工具，位于linux/scripts/，里面有一个decodecode工具可以用来转换机器码，decodecode脚本可以在没有源代码或符号表的情况下，将oops异常的log作为输入就可以解析出错误位置的汇编代码。
oops_log.txt内容如下
call trace:[ 867.148911] Exception stack(0xffffffc00a4ffa70 to 0xffffffc00a4ffba0)[ 867.148913] fa60: ffffff8000ef0000 0000008000000000[ 867.148916] fa80: ffffffc00a4ffc40 ffffff8000ef0024 ffffff80097c02f8 0000000000000002[ 867.148918] faa0: ffffffc00a4ffac0 000000020001b57c 0000000000000000 0000000100000000[ 867.148921] fac0: ffffffc00a4ffb60 ffffff800810d674 ffffffc00a4ffbc0 ffffff8000ef1024[ 867.148924] fae0: ffffffc0cdce10c0 ffffff80095b7860 0000000000000000 ffffff8000ef2050[ 867.148927] fb00: 0000000000000001 ffffffc0cde6e880 0000000000000000 0000000019760817[ 867.148929] fb20: 0000000000000007 0000000000000007 0000000000000001 ffffffc0f7f24b38[ 867.148932] fb40: 0000000000000022 ffffff80096280b0 ffffff8008463c3c 0000000005f5e0ff[ 867.148935] fb60: ffffff80097bfa9f 00000000fffffffe 0000000000000030 000000000000000a[ 867.148937] fb80: 00000000000224d6 0000000000000000 ffffff800813b204 0000007fb096c8a0[ 867.148944] [ltffffff8000ef0024gt] init_oopsdemo+0x24/0x38 [oops_module][ 867.148953] [ltffffff80080830f8gt] do_one_initcall+0x78/0x194[ 867.148958] [ltffffff800818d2d0gt] do_init_module+0x64/0x1c0[ 867.148962] [ltffffff800813ab5cgt] load_module+0x199c/0x1ed0[ 867.148964] [ltffffff800813b2b4gt] SyS_finit_module+0xb0/0xbc[ 867.148968] [ltffffff8008082f70gt] el0_svc_naked+0x24/0x2
$ ARCH=arm64 CROSS_COMPILE=/home/zhongyi/code/rk3399_linux_release_v2.5.10210301/prebuilts/gcc/linux-x86/aarch64/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu- ./scripts/decodecode lt /home/zhongyi/code/module/oops_module/oops_log.txtCode: 95ca7426 d2800000 528102e1 72a32ec1 (b9000001)All code======== 0: 95ca7426 .word 0x95ca7426 4: d2800000 .word 0xd2800000 8: 528102e1 .word 0x528102e1 c: 72a32ec1 .word 0x72a32ec1 10: b9000001 .word 0xb9000001 lt-- trapping instructionCode starting with the faulting instruction=========================================== 0: b9000001 .word 0xb9000001
执行脚本后，就可以得到出错的汇编代码。trapping instruction指出了出错的地址。根据oop_module.ko的反汇编可以知道出错的位置24: b9000001 str w1, [x0]。
注意脚本认为该机器码是跟host结构相同的原生机器码，想要跨架构翻译要指定架构和交叉工具链。
faddr2line
内核开发者为了方便问题的排查，也经常需要根据内核栈，快速定位导致问题发生的代码位置。所以，Linux 内核维护了一个 faddr2line 脚本，根据函数名+偏移量输出源码文件名和行号。
在使用这个脚本之前，还需要注意两个前提条件
之一，带有调试信息的内核文件，一般名字为 vmlinux（注意，/boot 目录下面的 vmlinz 是压缩后的内核，不可以直接拿来使用）。第二，系统中需要安装 awk、readelf、addr2line、size、nm 等命令。对于第二个条件，这些命令都包含在 binutils 软件包中，只需要执行 apt 或者 dnf 命令安装即可。而对之一个条件中的内核调试信息，各个主要的发行版也都提供了相应的软件仓库，你可以根据文档进行安装。比如，对于 Ubuntu 来说，你可以执行下面的命令安装调试信息
codename=$(l _release -cs)sudo tee /etc/apt/sources.list.d/ddebs.list ltlt EOFdeb http://ddebs.ubuntu.com/ ${codename} main restricted universe multiversedeb http://ddebs.ubuntu.com/ ${codename}-updates main restricted universe multiverseEOFsudo apt-get install -y ubuntu-dbgsym-keyringsudo apt-get updatesudo apt-get install -y linux-image-$(uname -r)-dbgsym
由于我们这里的oops 是发生在ko中，而不是内核。，使用faddr2line指定oops_module.ko 即可。
? kernel git:(firefly) ? scripts/faddr2line /home/zhongyi/code/module/oops_module/oops_module.ko init_oopsdemo+0x24init_oopsdemo+0x24/0x30:init_oopsdemo at /home/zhongyi/code/module/oops_module/oops_module.c:18
如果oops发生在内核中，将oops_module.ko 换成对应的vmlinux即可。
，贴下oops_module.c的源代码，感兴趣的大家可以自己写一个分析下。
#include ltlinux/init.hgt#include ltlinux/module.hgtMODULE_LICENSE(#34BSD/GPL#34)MODULE_AUTHOR(#34ZHONGYI#34)static int init_oopsdemo(void){ printk(#34oops module init! \n#34) ((int)0x00) = 0x19760817 return 0}module_init(init_oopsdemo)static void cleanup_oopsdemo(void){ printk(#34oops module exit! \n#34)}module_exit(cleanup_oopsdemo)MODULE_LICENSE(#34GPL#34)
原文链接https://mp.weixin.qq.com/s/88fULbJKe21mkKAnFbSeiw
转载自嵌入式与Linux那些事
文章来源于仲一
原文链接如何解读内核的oops
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