Commit 02e26bd9 authored by Marc Zyngier's avatar Marc Zyngier Committed by Greg Kroah-Hartman
Browse files

arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation

commit 986372c4

 upstream.

In order to avoid checking arm64_ssbd_callback_required on each
kernel entry/exit even if no mitigation is required, let's
add yet another alternative that by default jumps over the mitigation,
and that gets nop'ed out if we're doing dynamic mitigation.

Think of it as a poor man's static key...
Reviewed-by: default avatarJulien Grall <julien.grall@arm.com>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8d6907af
......@@ -285,6 +285,20 @@ void __init arm64_update_smccc_conduit(struct alt_instr *alt,
*updptr = cpu_to_le32(insn);
}
void __init arm64_enable_wa2_handling(struct alt_instr *alt,
__le32 *origptr, __le32 *updptr,
int nr_inst)
{
BUG_ON(nr_inst != 1);
/*
* Only allow mitigation on EL1 entry/exit and guest
* ARCH_WORKAROUND_2 handling if the SSBD state allows it to
* be flipped.
*/
if (arm64_get_ssbd_state() == ARM64_SSBD_KERNEL)
*updptr = cpu_to_le32(aarch64_insn_gen_nop());
}
static void arm64_set_ssbd_mitigation(bool state)
{
switch (psci_ops.conduit) {
......
......@@ -142,6 +142,9 @@ alternative_else_nop_endif
// to save/restore them if required.
.macro apply_ssbd, state, targ, tmp1, tmp2
#ifdef CONFIG_ARM64_SSBD
alternative_cb arm64_enable_wa2_handling
b \targ
alternative_cb_end
ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1
cbz \tmp2, \targ
mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
......
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