4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Zyngier <marc.zyngier@xxxxxxx> commit 5cf9ce6e5ea50f805c6188c04ed0daaec7b6887d upstream. In a heterogeneous system, we can end up with both affected and unaffected CPUs. Let's check their status before calling into the firmware. Reviewed-by: Julien Grall <julien.grall@xxxxxxx> Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx> Acked-by: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/kernel/cpu_errata.c | 2 ++ arch/arm64/kernel/entry.S | 11 +++++++---- 2 files changed, 9 insertions(+), 4 deletions(-) --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -188,6 +188,8 @@ static int enable_smccc_arch_workaround_ #endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */ #ifdef CONFIG_ARM64_SSBD +DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required); + void __init arm64_update_smccc_conduit(struct alt_instr *alt, __le32 *origptr, __le32 *updptr, int nr_inst) --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -98,8 +98,10 @@ alternative_else_nop_endif // This macro corrupts x0-x3. It is the caller's duty // to save/restore them if required. - .macro apply_ssbd, state + .macro apply_ssbd, state, targ, tmp1, tmp2 #ifdef CONFIG_ARM64_SSBD + ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 + cbz \tmp2, \targ mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 mov w1, #\state alternative_cb arm64_update_smccc_conduit @@ -135,12 +137,13 @@ alternative_cb_end ldr x19, [tsk, #TI_FLAGS] // since we can unmask debug disable_step_tsk x19, x20 // exceptions when scheduling. - apply_ssbd 1 + apply_ssbd 1, 1f, x22, x23 #ifdef CONFIG_ARM64_SSBD ldp x0, x1, [sp, #16 * 0] ldp x2, x3, [sp, #16 * 1] #endif +1: mov x29, xzr // fp pointed to user-space .else @@ -210,8 +213,8 @@ alternative_if ARM64_WORKAROUND_845719 alternative_else_nop_endif #endif 3: - apply_ssbd 0 - + apply_ssbd 0, 5f, x0, x1 +5: .endif msr elr_el1, x21 // set up the return data msr spsr_el1, x22
