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Message-Id: <86230818ac7bb48f7821d9c41d96a1233c4535c3.1443792303.git.jslaby@suse.cz> Date: Fri, 2 Oct 2015 15:24:46 +0200 From: Jiri Slaby <jslaby@...e.cz> To: stable@...r.kernel.org Cc: linux-kernel@...r.kernel.org, Will Deacon <will.deacon@....com>, Jiri Slaby <jslaby@...e.cz> Subject: [PATCH 3.12 41/84] arm64: errata: add module build workaround for erratum #843419 From: Will Deacon <will.deacon@....com> 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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@....com> Signed-off-by: Will Deacon <will.deacon@....com> Signed-off-by: Jiri Slaby <jslaby@...e.cz> --- arch/arm64/Kconfig | 16 ++++++++++++++++ arch/arm64/Makefile | 4 ++++ arch/arm64/kernel/module.c | 2 ++ 3 files changed, 22 insertions(+) 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; -- 2.6.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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