This is a note to let you know that I've just added the patch titled
arm64: errata: add module build workaround for erratum #843419
to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-errata-add-module-build-workaround-for-erratum-843419.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From df057cc7b4fa59e9b55f07ffdb6c62bf02e99a00 Mon Sep 17 00:00:00 2001
From: Will Deacon <[email protected]>
Date: Tue, 17 Mar 2015 12:15:02 +0000
Subject: arm64: errata: add module build workaround for erratum #843419
From: Will Deacon <[email protected]>
commit df057cc7b4fa59e9b55f07ffdb6c62bf02e99a00 upstream.
Cortex-A53 processors <= r0p4 are affected by erratum #843419 which can
lead to a memory access using an incorrect address in certain sequences
headed by an ADRP instruction.
There is a linker fix to generate veneers for ADRP instructions, but
this doesn't work for kernel modules which are built as unlinked ELF
objects.
This patch adds a new config option for the erratum which, when enabled,
builds kernel modules with the mcmodel=large flag. This uses absolute
addressing for all kernel symbols, thereby removing the use of ADRP as
a PC-relative form of addressing. The ADRP relocs are removed from the
module loader so that we fail to load any potentially affected modules.
Acked-by: Catalin Marinas <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/arm64/Kconfig | 16 ++++++++++++++++
arch/arm64/Makefile | 4 ++++
arch/arm64/kernel/module.c | 2 ++
3 files changed, 22 insertions(+)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -413,6 +413,22 @@ config ARM64_ERRATUM_845719
If unsure, say Y.
+config ARM64_ERRATUM_843419
+ bool "Cortex-A53: 843419: A load or store might access an incorrect
address"
+ depends on MODULES
+ default y
+ help
+ This option builds kernel modules using the large memory model in
+ order to avoid the use of the ADRP instruction, which can cause
+ a subsequent memory access to use an incorrect address on Cortex-A53
+ parts up to r0p4.
+
+ Note that the kernel itself must be linked with a version of ld
+ which fixes potentially affected ADRP instructions through the
+ use of veneers.
+
+ If unsure, say Y.
+
endmenu
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -30,6 +30,10 @@ endif
CHECKFLAGS += -D__aarch64__
+ifeq ($(CONFIG_ARM64_ERRATUM_843419), y)
+CFLAGS_MODULE += -mcmodel=large
+endif
+
# Default value
head-y := arch/arm64/kernel/head.o
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -332,12 +332,14 @@ int apply_relocate_add(Elf64_Shdr *sechd
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21,
AARCH64_INSN_IMM_ADR);
break;
+#ifndef CONFIG_ARM64_ERRATUM_843419
case R_AARCH64_ADR_PREL_PG_HI21_NC:
overflow_check = false;
case R_AARCH64_ADR_PREL_PG_HI21:
ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21,
AARCH64_INSN_IMM_ADR);
break;
+#endif
case R_AARCH64_ADD_ABS_LO12_NC:
case R_AARCH64_LDST8_ABS_LO12_NC:
overflow_check = false;
Patches currently in stable-queue which might be from [email protected] are
queue-4.1/arm64-head.s-initialise-mdcr_el2-in-el2_setup.patch
queue-4.1/arm64-set-max_memblock_addr-according-to-linear-region-size.patch
queue-4.1/arm64-kconfig-move-list_poison-to-a-safe-value.patch
queue-4.1/arm64-flush-fp-simd-state-correctly-after-execve.patch
queue-4.1/kvm-arm64-add-workaround-for-cortex-a57-erratum-852523.patch
queue-4.1/of-fdt-make-memblock-maximum-physical-address-arch-configurable.patch
queue-4.1/arm64-errata-add-module-build-workaround-for-erratum-843419.patch
queue-4.1/arm64-compat-fix-vfp-save-restore-across-signal-handlers-in-big-endian.patch
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