diff options
Diffstat (limited to 'arch/arm/mm/context.c')
-rw-r--r-- | arch/arm/mm/context.c | 84 |
1 files changed, 45 insertions, 39 deletions
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index 6eb97b3..845769e 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -144,21 +144,17 @@ static void flush_context(unsigned int cpu) /* Update the list of reserved ASIDs and the ASID bitmap. */ bitmap_clear(asid_map, 0, NUM_USER_ASIDS); for_each_possible_cpu(i) { - if (i == cpu) { - asid = 0; - } else { - asid = atomic64_xchg(&per_cpu(active_asids, i), 0); - /* - * If this CPU has already been through a - * rollover, but hasn't run another task in - * the meantime, we must preserve its reserved - * ASID, as this is the only trace we have of - * the process it is still running. - */ - if (asid == 0) - asid = per_cpu(reserved_asids, i); - __set_bit(asid & ~ASID_MASK, asid_map); - } + asid = atomic64_xchg(&per_cpu(active_asids, i), 0); + /* + * If this CPU has already been through a + * rollover, but hasn't run another task in + * the meantime, we must preserve its reserved + * ASID, as this is the only trace we have of + * the process it is still running. + */ + if (asid == 0) + asid = per_cpu(reserved_asids, i); + __set_bit(asid & ~ASID_MASK, asid_map); per_cpu(reserved_asids, i) = asid; } @@ -184,36 +180,46 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu) u64 asid = atomic64_read(&mm->context.id); u64 generation = atomic64_read(&asid_generation); - if (asid != 0 && is_reserved_asid(asid)) { + if (asid != 0) { /* - * Our current ASID was active during a rollover, we can - * continue to use it and this was just a false alarm. + * If our current ASID was active during a rollover, we + * can continue to use it and this was just a false alarm. */ - asid = generation | (asid & ~ASID_MASK); - } else { + if (is_reserved_asid(asid)) + return generation | (asid & ~ASID_MASK); + /* - * Allocate a free ASID. If we can't find one, take a - * note of the currently active ASIDs and mark the TLBs - * as requiring flushes. We always count from ASID #1, - * as we reserve ASID #0 to switch via TTBR0 and to - * avoid speculative page table walks from hitting in - * any partial walk caches, which could be populated - * from overlapping level-1 descriptors used to map both - * the module area and the userspace stack. + * We had a valid ASID in a previous life, so try to re-use + * it if possible., */ - asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, cur_idx); - if (asid == NUM_USER_ASIDS) { - generation = atomic64_add_return(ASID_FIRST_VERSION, - &asid_generation); - flush_context(cpu); - asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1); - } - __set_bit(asid, asid_map); - cur_idx = asid; - asid |= generation; - cpumask_clear(mm_cpumask(mm)); + asid &= ~ASID_MASK; + if (!__test_and_set_bit(asid, asid_map)) + goto bump_gen; } + /* + * Allocate a free ASID. If we can't find one, take a note of the + * currently active ASIDs and mark the TLBs as requiring flushes. + * We always count from ASID #1, as we reserve ASID #0 to switch + * via TTBR0 and to avoid speculative page table walks from hitting + * in any partial walk caches, which could be populated from + * overlapping level-1 descriptors used to map both the module + * area and the userspace stack. + */ + asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, cur_idx); + if (asid == NUM_USER_ASIDS) { + generation = atomic64_add_return(ASID_FIRST_VERSION, + &asid_generation); + flush_context(cpu); + asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1); + } + + __set_bit(asid, asid_map); + cur_idx = asid; + +bump_gen: + asid |= generation; + cpumask_clear(mm_cpumask(mm)); return asid; } |