diff options
Diffstat (limited to 'mm/kasan')
| -rw-r--r-- | mm/kasan/kasan_init.c | 44 | ||||
| -rw-r--r-- | mm/kasan/quarantine.c | 51 |
2 files changed, 83 insertions, 12 deletions
diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c index 31238dad85fb..b96a5f773d88 100644 --- a/mm/kasan/kasan_init.c +++ b/mm/kasan/kasan_init.c @@ -30,6 +30,9 @@ */ unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss; +#if CONFIG_PGTABLE_LEVELS > 4 +p4d_t kasan_zero_p4d[PTRS_PER_P4D] __page_aligned_bss; +#endif #if CONFIG_PGTABLE_LEVELS > 3 pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss; #endif @@ -82,10 +85,10 @@ static void __init zero_pmd_populate(pud_t *pud, unsigned long addr, } while (pmd++, addr = next, addr != end); } -static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr, +static void __init zero_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long end) { - pud_t *pud = pud_offset(pgd, addr); + pud_t *pud = pud_offset(p4d, addr); unsigned long next; do { @@ -107,6 +110,23 @@ static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr, } while (pud++, addr = next, addr != end); } +static void __init zero_p4d_populate(pgd_t *pgd, unsigned long addr, + unsigned long end) +{ + p4d_t *p4d = p4d_offset(pgd, addr); + unsigned long next; + + do { + next = p4d_addr_end(addr, end); + + if (p4d_none(*p4d)) { + p4d_populate(&init_mm, p4d, + early_alloc(PAGE_SIZE, NUMA_NO_NODE)); + } + zero_pud_populate(p4d, addr, next); + } while (p4d++, addr = next, addr != end); +} + /** * kasan_populate_zero_shadow - populate shadow memory region with * kasan_zero_page @@ -125,6 +145,7 @@ void __init kasan_populate_zero_shadow(const void *shadow_start, next = pgd_addr_end(addr, end); if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) { + p4d_t *p4d; pud_t *pud; pmd_t *pmd; @@ -135,9 +156,22 @@ void __init kasan_populate_zero_shadow(const void *shadow_start, * 3,2 - level page tables where we don't have * puds,pmds, so pgd_populate(), pud_populate() * is noops. + * + * The ifndef is required to avoid build breakage. + * + * With 5level-fixup.h, pgd_populate() is not nop and + * we reference kasan_zero_p4d. It's not defined + * unless 5-level paging enabled. + * + * The ifndef can be dropped once all KASAN-enabled + * architectures will switch to pgtable-nop4d.h. */ - pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_pud)); - pud = pud_offset(pgd, addr); +#ifndef __ARCH_HAS_5LEVEL_HACK + pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d)); +#endif + p4d = p4d_offset(pgd, addr); + p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud)); + pud = pud_offset(p4d, addr); pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); pmd = pmd_offset(pud, addr); pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); @@ -148,6 +182,6 @@ void __init kasan_populate_zero_shadow(const void *shadow_start, pgd_populate(&init_mm, pgd, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } - zero_pud_populate(pgd, addr, next); + zero_p4d_populate(pgd, addr, next); } while (pgd++, addr = next, addr != end); } diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index 6f1ed1630873..3a8ddf8baf7d 100644 --- a/mm/kasan/quarantine.c +++ b/mm/kasan/quarantine.c @@ -25,6 +25,7 @@ #include <linux/printk.h> #include <linux/shrinker.h> #include <linux/slab.h> +#include <linux/srcu.h> #include <linux/string.h> #include <linux/types.h> @@ -103,6 +104,7 @@ static int quarantine_tail; /* Total size of all objects in global_quarantine across all batches. */ static unsigned long quarantine_size; static DEFINE_SPINLOCK(quarantine_lock); +DEFINE_STATIC_SRCU(remove_cache_srcu); /* Maximum size of the global queue. */ static unsigned long quarantine_max_size; @@ -173,17 +175,22 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) struct qlist_head *q; struct qlist_head temp = QLIST_INIT; + /* + * Note: irq must be disabled until after we move the batch to the + * global quarantine. Otherwise quarantine_remove_cache() can miss + * some objects belonging to the cache if they are in our local temp + * list. quarantine_remove_cache() executes on_each_cpu() at the + * beginning which ensures that it either sees the objects in per-cpu + * lists or in the global quarantine. + */ local_irq_save(flags); q = this_cpu_ptr(&cpu_quarantine); qlist_put(q, &info->quarantine_link, cache->size); - if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) + if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) { qlist_move_all(q, &temp); - local_irq_restore(flags); - - if (unlikely(!qlist_empty(&temp))) { - spin_lock_irqsave(&quarantine_lock, flags); + spin_lock(&quarantine_lock); WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes); qlist_move_all(&temp, &global_quarantine[quarantine_tail]); if (global_quarantine[quarantine_tail].bytes >= @@ -196,20 +203,33 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) if (new_tail != quarantine_head) quarantine_tail = new_tail; } - spin_unlock_irqrestore(&quarantine_lock, flags); + spin_unlock(&quarantine_lock); } + + local_irq_restore(flags); } void quarantine_reduce(void) { size_t total_size, new_quarantine_size, percpu_quarantines; unsigned long flags; + int srcu_idx; struct qlist_head to_free = QLIST_INIT; if (likely(READ_ONCE(quarantine_size) <= READ_ONCE(quarantine_max_size))) return; + /* + * srcu critical section ensures that quarantine_remove_cache() + * will not miss objects belonging to the cache while they are in our + * local to_free list. srcu is chosen because (1) it gives us private + * grace period domain that does not interfere with anything else, + * and (2) it allows synchronize_srcu() to return without waiting + * if there are no pending read critical sections (which is the + * expected case). + */ + srcu_idx = srcu_read_lock(&remove_cache_srcu); spin_lock_irqsave(&quarantine_lock, flags); /* @@ -237,6 +257,7 @@ void quarantine_reduce(void) spin_unlock_irqrestore(&quarantine_lock, flags); qlist_free_all(&to_free, NULL); + srcu_read_unlock(&remove_cache_srcu, srcu_idx); } static void qlist_move_cache(struct qlist_head *from, @@ -280,12 +301,28 @@ void quarantine_remove_cache(struct kmem_cache *cache) unsigned long flags, i; struct qlist_head to_free = QLIST_INIT; + /* + * Must be careful to not miss any objects that are being moved from + * per-cpu list to the global quarantine in quarantine_put(), + * nor objects being freed in quarantine_reduce(). on_each_cpu() + * achieves the first goal, while synchronize_srcu() achieves the + * second. + */ on_each_cpu(per_cpu_remove_cache, cache, 1); spin_lock_irqsave(&quarantine_lock, flags); - for (i = 0; i < QUARANTINE_BATCHES; i++) + for (i = 0; i < QUARANTINE_BATCHES; i++) { + if (qlist_empty(&global_quarantine[i])) + continue; qlist_move_cache(&global_quarantine[i], &to_free, cache); + /* Scanning whole quarantine can take a while. */ + spin_unlock_irqrestore(&quarantine_lock, flags); + cond_resched(); + spin_lock_irqsave(&quarantine_lock, flags); + } spin_unlock_irqrestore(&quarantine_lock, flags); qlist_free_all(&to_free, cache); + + synchronize_srcu(&remove_cache_srcu); } |