The alternative code patching doesn't check if the replaced instruction uses a pc relative literal. This could cause silent corruption in the instruction stream as the instruction will be executed from a different address than what it was compiled for. Catch all such cases.
Cc: Marc Zyngier <marc.zyng...@arm.com> Cc: Andre Przywara <andre.przyw...@arm.com> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Catalin Marinas <catalin.mari...@arm.com> Suggested-by: Will Deacon <will.dea...@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com> --- arch/arm64/kernel/alternative.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c index d2ee1b2..6b269a9 100644 --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -80,6 +80,12 @@ static u32 get_alt_insn(struct alt_instr *alt, u32 *insnptr, u32 *altinsnptr) offset = target - (unsigned long)insnptr; insn = aarch64_set_branch_offset(insn, offset); } + } else if (aarch64_insn_uses_literal(insn)) { + /* + * Disallow patching unhandled instructions using PC relative + * literal addresses + */ + BUG(); } return insn; -- 2.7.4