[yocto] Fix for kernel 3.8/gcc-4.8 segfault on qemuarm

[Khem Raj]

Hi Bruce and All

Finally after a long innings I have diagnosed the mystery behind the below segfault that we see on kernel 3.8 which compiled with gcc 4.8 but don't show when compiled with gcc 4.7


Unable to handle kernel paging request at virtual address ffffffff
pgd = c0004000
[ffffffff] *pgd=07ffe831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT ARM
Modules linked in:
CPU: 0    Not tainted  (3.8.0-yocto-standard+ #32)
PC is at kmem_cache_alloc+0x38/0x154
LR is at subsys_system_register+0x34/0xd8
pc : [<c00bd4d8>]    lr : [<c0327244>]    psr: a0000153
sp : c7835ef0  ip : c7904590  fp : 00000000
r10: c0688dc4  r9 : c06db900  r8 : c0327244
r7 : 00000000  r6 : 000080d0  r5 : c7801380  r4 : ffffffff
r3 : 00000000  r2 : 00000078  r1 : 000080d0  r0 : c7801380
Flags: NzCv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment kernel
Control: 00093177  Table: 00004000  DAC: 00000017
Process swapper (pid: 1, stack limit = 0xc78341b8)
Stack: (0xc7835ef0 to 0xc7836000)
5ee0:                                     c06a5564 c06b8b8c c7834028 00000000
5f00: c0680218 c0327244 c7835f28 c06a5564 00000006 c7834028 c06db900 c0688dd4
5f20: c7835f28 c00089a0 c0657f44 00000006 c086e561 00000006 00000000 c06a5534
5f40: c06a5564 00000006 c06db900 c0680218 c069fd68 0000008e c069fd5c c0680924
5f60: 00000006 00000006 c0680218 00000000 00000000 00000000 00000000 00000000
5f80: c04f5e68 00000000 00000000 00000000 00000000 00000000 00000000 c04f5e70
5fa0: 00000000 00000000 c04f5e68 c000deb0 00000000 00000000 00000000 00000000
5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
5fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[<c00bd4d8>] (kmem_cache_alloc+0x38/0x154) from [<c0327244>] (subsys_system_register+0x34/0xd8)
[<c0327244>] (subsys_system_register+0x34/0xd8) from [<c0688dd4>] (init_clocksource_sysfs+0x10/0x54)
[<c0688dd4>] (init_clocksource_sysfs+0x10/0x54) from [<c00089a0>] (do_one_initcall+0x10c/0x17c)
[<c00089a0>] (do_one_initcall+0x10c/0x17c) from [<c0680924>] (kernel_init_freeable+0x164/0x224)
[<c0680924>] (kernel_init_freeable+0x164/0x224) from [<c04f5e70>] (kernel_init+0x8/0x150)
[<c04f5e70>] (kernel_init+0x8/0x150) from [<c000deb0>] (ret_from_fork+0x14/0x24)
Code: e5934000 e3540000 0a00001a e5953014 (e7941003)
---[ end trace f4d187650e17fc5c ]---
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b


Please apply the patch below to linux-yocto-3.8

http://sakrah.dontexist.org/files/patches/0001-ARM-7668-1-fix-memset-related-crashes-caused-by-rece.patch

This is a back port from 3.9 therefore safe. The problem is not limited to linux-yocto it also impacts upstream 3.8 stable
but 3.8 stable is end of life so why bother. If linux-yocto upgrades to 3.9 or 3.10 and drops 3.8 in 1.5 then we are ok too.

Let me know how it goes

Thanks

-Khem