powerpc/modules: Fix crashes by adding CONFIG_RELOCATABLE to vermagic
If you build the kernel with CONFIG_RELOCATABLE=n, then install the
modules, rebuild the kernel with CONFIG_RELOCATABLE=y and leave the
old modules installed, we crash something like:
Unable to handle kernel paging request for data at address 0xd000000018d66cef
Faulting instruction address: 0xc0000000021ddd08
Oops: Kernel access of bad area, sig: 11 [#1]
Modules linked in: x_tables autofs4
CPU: 2 PID: 1 Comm: systemd Not tainted 4.16.0-rc6-gcc_ubuntu_le-g99fec39 #1
...
NIP check_version.isra.22+0x118/0x170
Call Trace:
__ksymtab_xt_unregister_table+0x58/0xfffffffffffffcb8 [x_tables] (unreliable)
resolve_symbol+0xb4/0x150
load_module+0x10e8/0x29a0
SyS_finit_module+0x110/0x140
system_call+0x58/0x6c
This happens because since commit 71810db27c1c ("modversions: treat
symbol CRCs as 32 bit quantities"), a relocatable kernel encodes and
handles symbol CRCs differently from a non-relocatable kernel.
Although it's possible we could try and detect this situation and
handle it, it's much more robust to simply make the state of
CONFIG_RELOCATABLE part of the module vermagic.
Fixes: 71810db27c1c ("modversions: treat symbol CRCs as 32 bit quantities")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Ellerman