[REGRESSION in 3.18][PPC] PA Semi fails to boot after: of/base: Fix PowerPC address parsing hack

[Steven Rostedt]

A bug in ftrace was reported to me that affects ARM and ARM64 but not
x86. Looking at the code it appears to affect PowerPC as well. So I
booted up my old PA Semi, to give it a try. The last time I booted it
was for a 3.17 kernel. Unfortunately, for 4.0-rc2 it crashed with:

Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc0000000005cef88
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=2 PA Semi PWRficient
Modules linked in:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.0.0-rc2-test #50
task: c00000003816cb60 ti: c0000000381a4000 task.ti: c0000000381a4000
NIP: c0000000005cef88 LR: c00000000007c1a0 CTR: c00000000007c184
REGS: c0000000381a7a00 TRAP: 0300   Not tainted  (4.0.0-rc2-test)
MSR: 9000000000009032 <SF,HV,EE,ME,IR,DR,RI>  CR: 22000028  XER: 00000000
DAR: 0000000000000000 DSISR: 40000000 SOFTE: 0 
GPR00: c00000000007c1a0 c0000000381a7c80 c000000000af4b98 0000000000000001 
GPR04: 0000000000000000 0000000000000000 00000000000004ba 000000003d6de000 
GPR08: 0100000000000000 0000000000000000 c0000000381a4080 0000000000000000 
GPR12: 0000000024044042 c00000000ffff300 ffffffffffffffed 0000000000000000 
GPR16: c000000000afb920 c0000000381a4000 c0000000009ad648 c0000000009ae580 
GPR20: c0000000381a4080 c0000000381a4000 c0000000381a4080 c0000000381a4000 
GPR24: c0000000381a4000 c0000000381a4000 c000000000afb880 c0000000381a4000 
GPR28: c0000000009f8790 0000000000000000 c0000000381a4000 c000000000b02168 
NIP [c0000000005cef88] .check_astate+0x28/0x50
LR [c00000000007c1a0] sleep_common+0x14/0x74
Call Trace:
[c0000000381a7c80] [c000000000afb880] 0xc000000000afb880 (unreliable)
[c0000000381a7cf0] [c00000000007c1a0] sleep_common+0x14/0x74
[c0000000381a7d30] [c0000000000130f0] .arch_cpu_idle+0x70/0x160
[c0000000381a7db0] [c0000000000d6660] .cpu_startup_entry+0x320/0x5a0
[c0000000381a7ee0] [c000000000034570] .start_secondary+0x290/0x2c0
[c0000000381a7f90] [c000000000008bfc] start_secondary_prolog+0x10/0x14
Instruction dump:
60000000 60000000 7c0802a6 f8010010 f821ff91 60000000 60000000 3d220003 
39296870 a86d0038 e9290010 7c0004ac <7c004c2c> 0c000000 4c00012c 5463103a 
---[ end trace 40e864a431826b26 ]---

I kicked off a ktest bisect, and it came down to this commit:

commit 746c9e9f92dde2789908e51a354ba90a1962a2eb
Author: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Date:   Fri Nov 14 17:55:03 2014 +1100

    of/base: Fix PowerPC address parsing hack

When I revert this from v4.0-rc2, I can successfully boot my PA Semi
again.

-- Steve

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