On Wed, 29 Aug 2018 08:47:53 +0200 Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > The newly added code that emits ksymtab entries as pairs of 32-bit > relative references interacts poorly with the way powerpc lays out > its address space: when a module exports a per-CPU variable, the > primary module region covering the ksymtab entry -and thus the 32-bit > relative reference- is too far away from the actual per-CPU variable's > base address (to which the per-CPU offsets are applied to obtain the > respective address of each CPU's copy), resulting in corruption when > the module loader attempts to resolve symbol references of modules > that are loaded on top and link to the exported per-CPU symbol. > > So let's disable this feature on powerpc. Even though it implements > CONFIG_RELOCATABLE, it does not implement CONFIG_RANDOMIZE_BASE and > so KASLR kernels (which are the main target of the feature) do not > exist on powerpc anyway. Let's go with this for now. We have a bit more work to do with module loader, linker, percpu, or all of the above. Thanks everyone. Linus can you merge this? I think Michael is on vacation this week and things are pretty crashy without it here. Don't need to call him off the beach for it. Thanks, Nick > > Reported-by: Andreas Schwab <schwab@xxxxxxxxxxxxxx> > Suggested-by: Nicholas Piggin <nicholas.piggin@xxxxxxxxx> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > --- > arch/powerpc/Kconfig | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index db0b6eebbfa5..a80669209155 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -177,7 +177,6 @@ config PPC > select HAVE_ARCH_KGDB > select HAVE_ARCH_MMAP_RND_BITS > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > - select HAVE_ARCH_PREL32_RELOCATIONS > select HAVE_ARCH_SECCOMP_FILTER > select HAVE_ARCH_TRACEHOOK > select HAVE_CBPF_JIT if !PPC64 > -- > 2.17.1 >
