x86: simplify the 32-bit cpa code

simplify the 32-bit cpa code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 56 insertions, 123 deletions

diff --git a/arch/x86/mm/pageattr_32.c b/arch/x86/mm/pageattr_32.c
index 66688a630839..570a37bf1401 100644
--- a/arch/x86/mm/pageattr_32.c
+++ b/arch/x86/mm/pageattr_32.c
@@ -15,9 +15,6 @@
 #include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 
-static DEFINE_SPINLOCK(cpa_lock);
-static struct list_head df_list = LIST_HEAD_INIT(df_list);
-
 pte_t *lookup_address(unsigned long address, int *level)
 {
         pgd_t *pgd = pgd_offset_k(address);
@@ -48,9 +45,7 @@ split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
         pte_t *pbase;
         int i;
 
-        spin_unlock_irq(&cpa_lock);
         base = alloc_pages(GFP_KERNEL, 0);
-        spin_lock_irq(&cpa_lock);
         if (!base)
                 return NULL;
 
@@ -58,9 +53,6 @@ split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
          * page_private is used to track the number of entries in
          * the page table page that have non standard attributes.
          */
-        SetPagePrivate(base);
-        page_private(base) = 0;
-
         address = __pa(address);
         addr = address & LARGE_PAGE_MASK;
         pbase = (pte_t *)page_address(base);
@@ -73,36 +65,6 @@ split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
         return base;
 }
 
-static void cache_flush_page(struct page *p)
-{
-        void *addr = page_address(p);
-        int i;
-
-        for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
-                clflush(addr + i);
-}
-
-static void flush_kernel_map(void *arg)
-{
-        struct list_head *lh = (struct list_head *)arg;
-        struct page *p;
-
-        /*
-         * Flush all to work around Errata in early athlons regarding
-         * large page flushing.
-         */
-        __flush_tlb_all();
-
-        /* High level code is not ready for clflush yet */
-        if (0 && cpu_has_clflush) {
-                list_for_each_entry(p, lh, lru)
-                        cache_flush_page(p);
-        } else {
-                if (boot_cpu_data.x86_model >= 4)
-                        wbinvd();
-        }
-}
-
 static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
 {
         unsigned long flags;
@@ -127,36 +89,12 @@ static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
         spin_unlock_irqrestore(&pgd_lock, flags);
 }
 
-/*
- * No more special protections in this 2/4MB area - revert to a large
- * page again.
- */
-static inline void revert_page(struct page *kpte_page, unsigned long address)
-{
-        pgprot_t ref_prot;
-        pte_t *linear;
-
-        ref_prot =
-        ((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
-                ? PAGE_KERNEL_LARGE_EXEC : PAGE_KERNEL_LARGE;
-
-        linear = (pte_t *)
-                pmd_offset(pud_offset(pgd_offset_k(address), address), address);
-        set_pmd_pte(linear,  address,
-                    pfn_pte((__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT,
-                            ref_prot));
-}
-
-static inline void save_page(struct page *kpte_page)
-{
-        if (!test_and_set_bit(PG_arch_1, &kpte_page->flags))
-                list_add(&kpte_page->lru, &df_list);
-}
-
 static int __change_page_attr(struct page *page, pgprot_t prot)
 {
+        pgprot_t ref_prot = PAGE_KERNEL;
         struct page *kpte_page;
         unsigned long address;
+        pgprot_t oldprot;
         pte_t *kpte;
         int level;
 
@@ -167,58 +105,41 @@ static int __change_page_attr(struct page *page, pgprot_t prot)
         if (!kpte)
                 return -EINVAL;
 
+        oldprot = pte_pgprot(*kpte);
         kpte_page = virt_to_page(kpte);
         BUG_ON(PageLRU(kpte_page));
         BUG_ON(PageCompound(kpte_page));
 
-        if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
-                if (level == 3) {
-                        set_pte_atomic(kpte, mk_pte(page, prot));
-                } else {
-                        struct page *split;
-                        pgprot_t ref_prot;
-
-                        ref_prot =
-                        ((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
-                                ? PAGE_KERNEL_EXEC : PAGE_KERNEL;
-                        split = split_large_page(address, prot, ref_prot);
-                        if (!split)
-                                return -ENOMEM;
-
-                        set_pmd_pte(kpte, address, mk_pte(split, ref_prot));
-                        kpte_page = split;
-                }
-                page_private(kpte_page)++;
-        } else {
-                if (level == 3) {
-                        set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
-                        BUG_ON(page_private(kpte_page) == 0);
-                        page_private(kpte_page)--;
-                } else
-                        BUG();
-        }
-
         /*
-         * If the pte was reserved, it means it was created at boot
-         * time (not via split_large_page) and in turn we must not
-         * replace it with a largepage.
+         * Better fail early if someone sets the kernel text to NX.
+         * Does not cover __inittext
          */
+        BUG_ON(address >= (unsigned long)&_text &&
+                address < (unsigned long)&_etext &&
+               (pgprot_val(prot) & _PAGE_NX));
 
-        save_page(kpte_page);
-        if (!PageReserved(kpte_page)) {
-                if (cpu_has_pse && (page_private(kpte_page) == 0)) {
-                        paravirt_release_pt(page_to_pfn(kpte_page));
-                        revert_page(kpte_page, address);
-                }
+        if ((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
+                ref_prot = PAGE_KERNEL_EXEC;
+
+        ref_prot = canon_pgprot(ref_prot);
+        prot = canon_pgprot(prot);
+
+        if (level == 3) {
+                set_pte_atomic(kpte, mk_pte(page, prot));
+        } else {
+                struct page *split;
+                split = split_large_page(address, prot, ref_prot);
+                if (!split)
+                        return -ENOMEM;
+
+                /*
+                 * There's a small window here to waste a bit of RAM:
+                 */
+                set_pmd_pte(kpte, address, mk_pte(split, ref_prot));
         }
         return 0;
 }
 
-static inline void flush_map(struct list_head *l)
-{
-        on_each_cpu(flush_kernel_map, l, 1, 1);
-}
-
 /*
  * Change the page attributes of an page in the linear mapping.
  *
@@ -234,40 +155,52 @@ static inline void flush_map(struct list_head *l)
  */
 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 {
-        unsigned long flags;
         int err = 0, i;
 
-        spin_lock_irqsave(&cpa_lock, flags);
         for (i = 0; i < numpages; i++, page++) {
                 err = __change_page_attr(page, prot);
                 if (err)
                         break;
         }
-        spin_unlock_irqrestore(&cpa_lock, flags);
 
         return err;
 }
 EXPORT_SYMBOL(change_page_attr);
 
-void global_flush_tlb(void)
+int change_page_attr_addr(unsigned long addr, int numpages, pgprot_t prot)
 {
-        struct page *pg, *next;
-        struct list_head l;
+        int i;
+        unsigned long pfn = (addr >> PAGE_SHIFT);
 
+        for (i = 0; i < numpages; i++) {
+                if (!pfn_valid(pfn + i)) {
+                        break;
+                } else {
+                        int level;
+                        pte_t *pte = lookup_address(addr + i*PAGE_SIZE, &level);
+                        BUG_ON(pte && !pte_none(*pte));
+                }
+        }
+        return change_page_attr(virt_to_page(addr), i, prot);
+}
+
+static void flush_kernel_map(void *arg)
+{
+        /*
+         * Flush all to work around Errata in early athlons regarding
+         * large page flushing.
+         */
+        __flush_tlb_all();
+
+        if (boot_cpu_data.x86_model >= 4)
+                wbinvd();
+}
+
+void global_flush_tlb(void)
+{
         BUG_ON(irqs_disabled());
 
-        spin_lock_irq(&cpa_lock);
-        list_replace_init(&df_list, &l);
-        spin_unlock_irq(&cpa_lock);
-        flush_map(&l);
-        list_for_each_entry_safe(pg, next, &l, lru) {
-                list_del(&pg->lru);
-                clear_bit(PG_arch_1, &pg->flags);
-                if (PageReserved(pg) || !cpu_has_pse || page_private(pg) != 0)
-                        continue;
-                ClearPagePrivate(pg);
-                __free_page(pg);
-        }
+        on_each_cpu(flush_kernel_map, NULL, 1, 1);
 }
 EXPORT_SYMBOL(global_flush_tlb);