Revert "MIPS: Remove race window in page fault handling"

Revert commit 2a4a8b1e5d9d ("MIPS: Remove race window in page fault
handling") because it increased the number of flushed dcache pages and
became a performance problem for some workloads.

Signed-off-by: Lars Persson <larper@axis.com>
Cc: linux-mips@linux-mips.org
Cc: paul.burton@imgtec.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9345/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 8 insertions, 19 deletions

diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 7e3ea7766822..f7b91d3a371d 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -119,36 +119,25 @@ void __flush_anon_page(struct page *page, unsigned long vmaddr)
 
 EXPORT_SYMBOL(__flush_anon_page);
 
-static void mips_flush_dcache_from_pte(pte_t pteval, unsigned long address)
+void __update_cache(struct vm_area_struct *vma, unsigned long address,
+        pte_t pte)
 {
         struct page *page;
-        unsigned long pfn = pte_pfn(pteval);
+        unsigned long pfn, addr;
+        int exec = (vma->vm_flags & VM_EXEC) && !cpu_has_ic_fills_f_dc;
 
+        pfn = pte_pfn(pte);
         if (unlikely(!pfn_valid(pfn)))
                 return;
-
         page = pfn_to_page(pfn);
         if (page_mapping(page) && Page_dcache_dirty(page)) {
-                unsigned long page_addr = (unsigned long) page_address(page);
-
-                if (!cpu_has_ic_fills_f_dc ||
-                    pages_do_alias(page_addr, address & PAGE_MASK))
-                        flush_data_cache_page(page_addr);
+                addr = (unsigned long) page_address(page);
+                if (exec || pages_do_alias(addr, address & PAGE_MASK))
+                        flush_data_cache_page(addr);
                 ClearPageDcacheDirty(page);
         }
 }
 
-void set_pte_at(struct mm_struct *mm, unsigned long addr,
-        pte_t *ptep, pte_t pteval)
-{
-        if (cpu_has_dc_aliases || !cpu_has_ic_fills_f_dc) {
-                if (pte_present(pteval))
-                        mips_flush_dcache_from_pte(pteval, addr);
-        }
-
-        set_pte(ptep, pteval);
-}
-
 unsigned long _page_cachable_default;
 EXPORT_SYMBOL(_page_cachable_default);