Commit 86230818 authored by Will Deacon's avatar Will Deacon Committed by Jiri Slaby

arm64: errata: add module build workaround for erratum #843419

commit df057cc7 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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
parent 3ebb3728
...@@ -269,6 +269,22 @@ config SYSVIPC_COMPAT ...@@ -269,6 +269,22 @@ config SYSVIPC_COMPAT
def_bool y def_bool y
depends on COMPAT && SYSVIPC 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 endmenu
source "net/Kconfig" source "net/Kconfig"
......
...@@ -28,6 +28,10 @@ comma = , ...@@ -28,6 +28,10 @@ comma = ,
CHECKFLAGS += -D__aarch64__ CHECKFLAGS += -D__aarch64__
ifeq ($(CONFIG_ARM64_ERRATUM_843419), y)
CFLAGS_MODULE += -mcmodel=large
endif
# Default value # Default value
head-y := arch/arm64/kernel/head.o head-y := arch/arm64/kernel/head.o
......
...@@ -390,12 +390,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, ...@@ -390,12 +390,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21, ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21,
INSN_IMM_ADR); INSN_IMM_ADR);
break; break;
#ifndef CONFIG_ARM64_ERRATUM_843419
case R_AARCH64_ADR_PREL_PG_HI21_NC: case R_AARCH64_ADR_PREL_PG_HI21_NC:
overflow_check = false; overflow_check = false;
case R_AARCH64_ADR_PREL_PG_HI21: case R_AARCH64_ADR_PREL_PG_HI21:
ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21, ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21,
INSN_IMM_ADR); INSN_IMM_ADR);
break; break;
#endif
case R_AARCH64_ADD_ABS_LO12_NC: case R_AARCH64_ADD_ABS_LO12_NC:
case R_AARCH64_LDST8_ABS_LO12_NC: case R_AARCH64_LDST8_ABS_LO12_NC:
overflow_check = false; overflow_check = false;
......
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