The patch titled
Subject: powerpc: disable support for relative ksymtab references
has been added to the -mm tree. Its filename is
powerpc-disable-support-for-relative-ksymtab-references.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/powerpc-disable-support-for-relative-ksymtab-references.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/powerpc-disable-support-for-relative-ksymtab-references.patch
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------------------------------------------------------
From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Subject: powerpc: disable support for relative ksymtab references
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.
Link: http://lkml.kernel.org/r/20180829064753.7133-1-ard.biesheuvel@xxxxxxxxxx
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reported-by: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
Suggested-by: Nicholas Piggin <nicholas.piggin@xxxxxxxxx>
Acked-by: Nicholas Piggin <nicholas.piggin@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/Kconfig | 1 -
1 file changed, 1 deletion(-)
--- a/arch/powerpc/Kconfig~powerpc-disable-support-for-relative-ksymtab-references
+++ a/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
_
Patches currently in -mm which might be from ard.biesheuvel@xxxxxxxxxx are
powerpc-disable-support-for-relative-ksymtab-references.patch
