David Miller writes:
> From: Anatoly Pugachev <matorola@xxxxxxxxx>
> Date: Tue, 1 Aug 2017 01:01:47 +0300
>
> > I don't know how to run on a running kernel , but as I understood:
> >
> > root@v215:strace# gzip -dc /boot/vmlinuz-4.12.0 > vmlinux
> > root@v215:strace# gdb -q vmlinux
> > Reading symbols from vmlinux...(no debugging symbols found)...done.
> > (gdb) x/20i 0x49b294 - 16
>
> Unfortunately you need to do this on the build kernel image before it
> has been stripped of all of it's symbols.
>
> Mikael, you built your kernels right?
>
> Go into one of your OOPS's and extract the "RPC: " hex value, and run
> the gdb command:
>
> bash$ cd src/linux
> bash$ gdb ./vmlinux
> (gdb) x/10i 0x${RPC_HEX_VALUE} - 16
>
> Thanks.
Ok, with 4.13-rc3 I got
[ 240.085153] Unable to handle kernel NULL pointer dereference
[ 240.142397] tsk->{mm,active_mm}->context = 000000000000044a
[ 240.198531] tsk->{mm,active_mm}->pgd = fff000023c784000
[ 240.250112] \|/ ____ \|/
"@'/ .. \`@"
/_| \__/ |_\
\__U_/
[ 240.374879] poll(724): Oops [#1]
[ 240.400132] CPU: 0 PID: 724 Comm: poll Not tainted 4.13.0-rc3 #1
[ 240.462002] task: fff000123cc71e00 task.stack: fff000123c894000
[ 240.522717] TSTATE: 0000004411001605 TPC: 00000000007570fc TNPC: 0000000000757110 Y: 00000000 Not tainted
[ 240.634921] TPC: <__bzero+0x20/0xc0>
[ 240.664747] g0: fff000123c897081 g1: 0000000000000000 g2: 0000000000000000 g3: 00000000008ca100
[ 240.762068] g4: fff000123cc71e00 g5: fff000023ef44000 g6: fff000123c894000 g7: 0000000000000008
[ 240.859389] o0: 000000000000000c o1: fff000123c897a80 o2: 0000000000000000 o3: 000000000000000c
[ 240.956718] o4: fff000123c897a7c o5: 00000000000000fb sp: fff000123c897181 ret_pc: 0000000000516ee0
[ 241.058627] RPC: <do_sys_poll+0x80/0x3c0>
[ 241.094166] l0: 0000000000000002 l1: 00000000014000c0 l2: 00000000000003fe l3: fff000123c897a7c
[ 241.191506] l4: 0000000000000000 l5: 0000000000000000 l6: 000000000000006d l7: ffffffffffffffea
[ 241.288822] i0: 00000000f7d93ff8 i1: 0000000000000002 i2: fff000123c897e90 i3: fff000123c897a70
[ 241.386141] i4: 000fffedc3768590 i5: fff000123c897a70 i6: fff000123c8975e1 i7: 00000000005177f8
[ 241.483468] I7: <SyS_poll+0x74/0xd0>
[ 241.513292] Call Trace:
[ 241.528265] [00000000005177f8] SyS_poll+0x74/0xd0
[ 241.574140] [00000000004061b4] linux_sparc_syscall32+0x34/0x60
[ 241.634847] Disabling lock debugging due to kernel taint
[ 241.687555] Caller[00000000005177f8]: SyS_poll+0x74/0xd0
[ 241.740276] Caller[00000000004061b4]: linux_sparc_syscall32+0x34/0x60
[ 241.807855] Caller[0000000000010a20]: 0x10a20
[ 241.847983] Instruction DUMP:
[ 241.847987] c56a2000
[ 241.869824] 808a2003
[ 241.883651] 02480006
[ 241.897475] <d42a2000>
[ 241.911207] 90022001
[ 241.925032] 808a2003
[ 241.938755] 1247fffd
[ 241.952484] 92226001
[ 241.966310] 808a2007
so the RPC should be do_sys_poll+0x80 right? Then gdb on the original vmlinux said:
(gdb) x/10i do_sys_poll+0x80-16
0x516ed0 <do_sys_poll+112>: brz %o0, 0x5170fc <do_sys_poll+668>
0x516ed4 <do_sys_poll+116>: mov %o0, %o2
0x516ed8 <do_sys_poll+120>: sub %i4, %o0, %i4
0x516edc <do_sys_poll+124>: clr %o1
0x516ee0 <do_sys_poll+128>: call 0x7570b8 <memset>
0x516ee4 <do_sys_poll+132>: add %l3, %i4, %o0
0x516ee8 <do_sys_poll+136>: b %xcc, 0x5170b0 <do_sys_poll+592>
0x516eec <do_sys_poll+140>: mov -14, %l7
0x516ef0 <do_sys_poll+144>: mov %l2, %o0
0x516ef4 <do_sys_poll+148>: movleu %xcc, %l0, %o0
(gdb)
/Mikael
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