From 9abd515a6e4a5c58c6eb4d04110430325eb5f5ac Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Thu, 27 Feb 2020 09:34:47 +0100 Subject: arm64: context: Fix ASID limit in boot messages Since commit f88f42f853a8 ("arm64: context: Free up kernel ASIDs if KPTI is not in use"), the NUM_USER_ASIDS macro doesn't correspond to the effective number of ASIDs when KPTI is enabled. Get an accurate number of available ASIDs in an arch_initcall, once we've discovered all CPUs' capabilities and know if we still need to halve the ASID space for KPTI. Fixes: f88f42f853a8 ("arm64: context: Free up kernel ASIDs if KPTI is not in use") Reviewed-by: Vladimir Murzin Signed-off-by: Jean-Philippe Brucker Signed-off-by: Will Deacon --- arch/arm64/mm/context.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) (limited to 'arch') diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index 8ef73e89d514..d89bb22589f6 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -260,14 +260,26 @@ asmlinkage void post_ttbr_update_workaround(void) CONFIG_CAVIUM_ERRATUM_27456)); } -static int asids_init(void) +static int asids_update_limit(void) { - asid_bits = get_cpu_asid_bits(); + unsigned long num_available_asids = NUM_USER_ASIDS; + + if (arm64_kernel_unmapped_at_el0()) + num_available_asids /= 2; /* * Expect allocation after rollover to fail if we don't have at least * one more ASID than CPUs. ASID #0 is reserved for init_mm. */ - WARN_ON(NUM_USER_ASIDS - 1 <= num_possible_cpus()); + WARN_ON(num_available_asids - 1 <= num_possible_cpus()); + pr_info("ASID allocator initialised with %lu entries\n", + num_available_asids); + return 0; +} +arch_initcall(asids_update_limit); + +static int asids_init(void) +{ + asid_bits = get_cpu_asid_bits(); atomic64_set(&asid_generation, ASID_FIRST_VERSION); asid_map = kcalloc(BITS_TO_LONGS(NUM_USER_ASIDS), sizeof(*asid_map), GFP_KERNEL); @@ -282,8 +294,6 @@ static int asids_init(void) */ if (IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) set_kpti_asid_bits(); - - pr_info("ASID allocator initialised with %lu entries\n", NUM_USER_ASIDS); return 0; } early_initcall(asids_init); -- cgit v1.2.3-59-g8ed1b