diff options
| -rw-r--r-- | arch/x86/mm/pageattr.c | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index f5e8663c0f7..b6374d653d0 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -35,6 +35,14 @@ struct cpa_data { int curpage; }; +/* + * Serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings) + * using cpa_lock. So that we don't allow any other cpu, with stale large tlb + * entries change the page attribute in parallel to some other cpu + * splitting a large page entry along with changing the attribute. + */ +static DEFINE_SPINLOCK(cpa_lock); + #define CPA_FLUSHTLB 1 #define CPA_ARRAY 2 @@ -453,7 +461,13 @@ static int split_large_page(pte_t *kpte, unsigned long address) unsigned int i, level; pte_t *pbase, *tmp; pgprot_t ref_prot; - struct page *base = alloc_pages(GFP_KERNEL, 0); + struct page *base; + + if (!debug_pagealloc) + spin_unlock(&cpa_lock); + base = alloc_pages(GFP_KERNEL, 0); + if (!debug_pagealloc) + spin_lock(&cpa_lock); if (!base) return -ENOMEM; @@ -594,7 +608,25 @@ repeat: */ err = split_large_page(kpte, address); if (!err) { - cpa->flags |= CPA_FLUSHTLB; + /* + * Do a global flush tlb after splitting the large page + * and before we do the actual change page attribute in the PTE. + * + * With out this, we violate the TLB application note, that says + * "The TLBs may contain both ordinary and large-page + * translations for a 4-KByte range of linear addresses. This + * may occur if software modifies the paging structures so that + * the page size used for the address range changes. If the two + * translations differ with respect to page frame or attributes + * (e.g., permissions), processor behavior is undefined and may + * be implementation-specific." + * + * We do this global tlb flush inside the cpa_lock, so that we + * don't allow any other cpu, with stale tlb entries change the + * page attribute in parallel, that also falls into the + * just split large page entry. + */ + flush_tlb_all(); goto repeat; } @@ -686,7 +718,11 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias) if (cpa->flags & CPA_ARRAY) cpa->numpages = 1; + if (!debug_pagealloc) + spin_lock(&cpa_lock); ret = __change_page_attr(cpa, checkalias); + if (!debug_pagealloc) + spin_unlock(&cpa_lock); if (ret) return ret; |