From 007ccec53da35528bd06fa0063da55b1311054c1 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 4 Feb 2016 12:24:46 +0100 Subject: [PATCH] s390/pageattr: do a single TLB flush for change_page_attr The change of the access rights for an address range in the kernel address space is currently done with a loop of IPTE + a store of the modified PTE. Between the IPTE and the store the PTE will be invalid, this intermediate state can cause problems with concurrent accesses. Consider a change of a kernel area from read-write to read-only, a concurrent reader of that area should be fine but with the invalid PTE it might get an unexpected exception. Remove the IPTEs for each PTE and do a global flush after all PTEs have been modified. Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/mm/pageattr.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index 749c98407b41..f2a5c29a97e9 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -65,19 +65,17 @@ static pte_t *walk_page_table(unsigned long addr) static void change_page_attr(unsigned long addr, int numpages, pte_t (*set) (pte_t)) { - pte_t *ptep, pte; + pte_t *ptep; int i; for (i = 0; i < numpages; i++) { ptep = walk_page_table(addr); if (WARN_ON_ONCE(!ptep)) break; - pte = *ptep; - pte = set(pte); - __ptep_ipte(addr, ptep); - *ptep = pte; + *ptep = set(*ptep); addr += PAGE_SIZE; } + __tlb_flush_kernel(); } int set_memory_ro(unsigned long addr, int numpages) -- 2.20.1