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| author | Will Deacon <will.deacon@arm.com> | 2015-03-17 12:15:02 +0000 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-09-30 11:00:04 +0200 |
| commit | 86230818ac7bb48f7821d9c41d96a1233c4535c3 (patch) | |
| tree | bc551c7406bbb570bd7416f2a051d5fb5258d0c6 | |
| parent | 3ebb37283c93282592beba3f01e46c8f8371dee8 (diff) | |
| download | lwn-86230818ac7bb48f7821d9c41d96a1233c4535c3.tar.gz lwn-86230818ac7bb48f7821d9c41d96a1233c4535c3.zip | |
arm64: errata: add module build workaround for erratum #843419
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 <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | arch/arm64/Kconfig | 16 | ||||
| -rw-r--r-- | arch/arm64/Makefile | 4 | ||||
| -rw-r--r-- | arch/arm64/kernel/module.c | 2 |
3 files changed, 22 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b07f9f356b87..c6ab435557b2 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -269,6 +269,22 @@ config SYSVIPC_COMPAT def_bool y depends on COMPAT && SYSVIPC +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 source "net/Kconfig" diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index d90cf79f233a..4148c05df99a 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -28,6 +28,10 @@ comma = , CHECKFLAGS += -D__aarch64__ +ifeq ($(CONFIG_ARM64_ERRATUM_843419), y) +CFLAGS_MODULE += -mcmodel=large +endif + # Default value head-y := arch/arm64/kernel/head.o diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index ca0e3d55da99..9589a92f6332 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -390,12 +390,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21, 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, INSN_IMM_ADR); break; +#endif case R_AARCH64_ADD_ABS_LO12_NC: case R_AARCH64_LDST8_ABS_LO12_NC: overflow_check = false; |