diff options
Diffstat (limited to 'mm/highmem.c')
| -rw-r--r-- | mm/highmem.c | 99 |
1 files changed, 89 insertions, 10 deletions
diff --git a/mm/highmem.c b/mm/highmem.c index 39aaca1a1ece..d1ef06aa6de6 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -365,8 +365,6 @@ EXPORT_SYMBOL(kunmap_high); #include <asm/kmap_size.h> -static DEFINE_PER_CPU(int, __kmap_local_idx); - /* * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second * slot is unused which acts as a guard page @@ -379,23 +377,21 @@ static DEFINE_PER_CPU(int, __kmap_local_idx); static inline int kmap_local_idx_push(void) { - int idx = __this_cpu_add_return(__kmap_local_idx, KM_INCR) - 1; - WARN_ON_ONCE(in_irq() && !irqs_disabled()); - BUG_ON(idx >= KM_MAX_IDX); - return idx; + current->kmap_ctrl.idx += KM_INCR; + BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX); + return current->kmap_ctrl.idx - 1; } static inline int kmap_local_idx(void) { - return __this_cpu_read(__kmap_local_idx) - 1; + return current->kmap_ctrl.idx - 1; } static inline void kmap_local_idx_pop(void) { - int idx = __this_cpu_sub_return(__kmap_local_idx, KM_INCR); - - BUG_ON(idx < 0); + current->kmap_ctrl.idx -= KM_INCR; + BUG_ON(current->kmap_ctrl.idx < 0); } #ifndef arch_kmap_local_post_map @@ -464,6 +460,7 @@ void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot) pteval = pfn_pte(pfn, prot); set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval); arch_kmap_local_post_map(vaddr, pteval); + current->kmap_ctrl.pteval[kmap_local_idx()] = pteval; preempt_enable(); return (void *)vaddr; @@ -522,10 +519,92 @@ void kunmap_local_indexed(void *vaddr) arch_kmap_local_pre_unmap(addr); pte_clear(&init_mm, addr, kmap_pte - idx); arch_kmap_local_post_unmap(addr); + current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0); kmap_local_idx_pop(); preempt_enable(); } EXPORT_SYMBOL(kunmap_local_indexed); + +/* + * Invoked before switch_to(). This is safe even when during or after + * clearing the maps an interrupt which needs a kmap_local happens because + * the task::kmap_ctrl.idx is not modified by the unmapping code so a + * nested kmap_local will use the next unused index and restore the index + * on unmap. The already cleared kmaps of the outgoing task are irrelevant + * because the interrupt context does not know about them. The same applies + * when scheduling back in for an interrupt which happens before the + * restore is complete. + */ +void __kmap_local_sched_out(void) +{ + struct task_struct *tsk = current; + pte_t *kmap_pte = kmap_get_pte(); + int i; + + /* Clear kmaps */ + for (i = 0; i < tsk->kmap_ctrl.idx; i++) { + pte_t pteval = tsk->kmap_ctrl.pteval[i]; + unsigned long addr; + int idx; + + /* With debug all even slots are unmapped and act as guard */ + if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !(i & 0x01)) { + WARN_ON_ONCE(!pte_none(pteval)); + continue; + } + if (WARN_ON_ONCE(pte_none(pteval))) + continue; + + /* + * This is a horrible hack for XTENSA to calculate the + * coloured PTE index. Uses the PFN encoded into the pteval + * and the map index calculation because the actual mapped + * virtual address is not stored in task::kmap_ctrl. + * For any sane architecture this is optimized out. + */ + idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); + + addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + arch_kmap_local_pre_unmap(addr); + pte_clear(&init_mm, addr, kmap_pte - idx); + arch_kmap_local_post_unmap(addr); + } +} + +void __kmap_local_sched_in(void) +{ + struct task_struct *tsk = current; + pte_t *kmap_pte = kmap_get_pte(); + int i; + + /* Restore kmaps */ + for (i = 0; i < tsk->kmap_ctrl.idx; i++) { + pte_t pteval = tsk->kmap_ctrl.pteval[i]; + unsigned long addr; + int idx; + + /* With debug all even slots are unmapped and act as guard */ + if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !(i & 0x01)) { + WARN_ON_ONCE(!pte_none(pteval)); + continue; + } + if (WARN_ON_ONCE(pte_none(pteval))) + continue; + + /* See comment in __kmap_local_sched_out() */ + idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); + addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + set_pte_at(&init_mm, addr, kmap_pte - idx, pteval); + arch_kmap_local_post_map(addr, pteval); + } +} + +void kmap_local_fork(struct task_struct *tsk) +{ + if (WARN_ON_ONCE(tsk->kmap_ctrl.idx)) + memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl)); +} + #endif #if defined(HASHED_PAGE_VIRTUAL) |