arm64: errata: add module build workaround for erratum #843419
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.
Cc: <stable@vger.kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 67bf410..876eb8d 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -332,12 +332,14 @@
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;