mm/vmalloc: track which page-table levels were modified

Track at which levels in the page-table entries were modified by
vmap/vunmap.

After the page-table has been modified, use that information do decide
whether the new arch_sync_kernel_mappings() needs to be called.

[akpm@linux-foundation.org: map_kernel_range_noflush() needs the arch_sync_kernel_mappings() call]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200515140023.25469-3-joro@8bytes.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 3332926..0efc35d 100644 (file)
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -133,6 +133,22 @@ extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
 void vmalloc_sync_mappings(void);
 void vmalloc_sync_unmappings(void);
 
+/*
+ * Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
+ * and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()
+ * needs to be called.
+ */
+#ifndef ARCH_PAGE_TABLE_SYNC_MASK
+#define ARCH_PAGE_TABLE_SYNC_MASK 0
+#endif
+
+/*
+ * There is no default implementation for arch_sync_kernel_mappings(). It is
+ * relied upon the compiler to optimize calls out if ARCH_PAGE_TABLE_SYNC_MASK
+ * is 0.
+ */
+void arch_sync_kernel_mappings(unsigned long start, unsigned long end);
+
 /*
  *     Lowlevel-APIs (not for driver use!)
  */

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 410bfe2..154e339 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -69,7 +69,8 @@ static void free_work(struct work_struct *w)
 
 /*** Page table manipulation functions ***/
 
-static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
+static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+                            pgtbl_mod_mask *mask)
 {
        pte_t *pte;
 
@@ -78,59 +79,81 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
                pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
                WARN_ON(!pte_none(ptent) && !pte_present(ptent));
        } while (pte++, addr += PAGE_SIZE, addr != end);
+       *mask |= PGTBL_PTE_MODIFIED;
 }
 
-static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
+static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
+                            pgtbl_mod_mask *mask)
 {
        pmd_t *pmd;
        unsigned long next;
+       int cleared;
 
        pmd = pmd_offset(pud, addr);
        do {
                next = pmd_addr_end(addr, end);
-               if (pmd_clear_huge(pmd))
+
+               cleared = pmd_clear_huge(pmd);
+               if (cleared || pmd_bad(*pmd))
+                       *mask |= PGTBL_PMD_MODIFIED;
+
+               if (cleared)
                        continue;
                if (pmd_none_or_clear_bad(pmd))
                        continue;
-               vunmap_pte_range(pmd, addr, next);
+               vunmap_pte_range(pmd, addr, next, mask);
        } while (pmd++, addr = next, addr != end);
 }
 
-static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end)
+static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
+                            pgtbl_mod_mask *mask)
 {
        pud_t *pud;
        unsigned long next;
+       int cleared;
 
        pud = pud_offset(p4d, addr);
        do {
                next = pud_addr_end(addr, end);
-               if (pud_clear_huge(pud))
+
+               cleared = pud_clear_huge(pud);
+               if (cleared || pud_bad(*pud))
+                       *mask |= PGTBL_PUD_MODIFIED;
+
+               if (cleared)
                        continue;
                if (pud_none_or_clear_bad(pud))
                        continue;
-               vunmap_pmd_range(pud, addr, next);
+               vunmap_pmd_range(pud, addr, next, mask);
        } while (pud++, addr = next, addr != end);
 }
 
-static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
+static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
+                            pgtbl_mod_mask *mask)
 {
        p4d_t *p4d;
        unsigned long next;
+       int cleared;
 
        p4d = p4d_offset(pgd, addr);
        do {
                next = p4d_addr_end(addr, end);
-               if (p4d_clear_huge(p4d))
+
+               cleared = p4d_clear_huge(p4d);
+               if (cleared || p4d_bad(*p4d))
+                       *mask |= PGTBL_P4D_MODIFIED;
+
+               if (cleared)
                        continue;
                if (p4d_none_or_clear_bad(p4d))
                        continue;
-               vunmap_pud_range(p4d, addr, next);
+               vunmap_pud_range(p4d, addr, next, mask);
        } while (p4d++, addr = next, addr != end);
 }
 
 /**
  * unmap_kernel_range_noflush - unmap kernel VM area
- * @addr: start of the VM area to unmap
+ * @start: start of the VM area to unmap
  * @size: size of the VM area to unmap
  *
  * Unmap PFN_UP(@size) pages at @addr.  The VM area @addr and @size specify
@@ -141,24 +164,33 @@ static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
  * for calling flush_cache_vunmap() on to-be-mapped areas before calling this
  * function and flush_tlb_kernel_range() after.
  */
-void unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
+void unmap_kernel_range_noflush(unsigned long start, unsigned long size)
 {
-       unsigned long end = addr + size;
+       unsigned long end = start + size;
        unsigned long next;
        pgd_t *pgd;
+       unsigned long addr = start;
+       pgtbl_mod_mask mask = 0;
 
        BUG_ON(addr >= end);
+       start = addr;
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, end);
+               if (pgd_bad(*pgd))
+                       mask |= PGTBL_PGD_MODIFIED;
                if (pgd_none_or_clear_bad(pgd))
                        continue;
-               vunmap_p4d_range(pgd, addr, next);
+               vunmap_p4d_range(pgd, addr, next, &mask);
        } while (pgd++, addr = next, addr != end);
+
+       if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
+               arch_sync_kernel_mappings(start, end);
 }
 
 static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
-               unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+               unsigned long end, pgprot_t prot, struct page **pages, int *nr,
+               pgtbl_mod_mask *mask)
 {
        pte_t *pte;
 
@@ -167,7 +199,7 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
         * callers keep track of where we're up to.
         */
 
-       pte = pte_alloc_kernel(pmd, addr);
+       pte = pte_alloc_kernel_track(pmd, addr, mask);
        if (!pte)
                return -ENOMEM;
        do {
@@ -180,55 +212,59 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
                set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
                (*nr)++;
        } while (pte++, addr += PAGE_SIZE, addr != end);
+       *mask |= PGTBL_PTE_MODIFIED;
        return 0;
 }
 
 static int vmap_pmd_range(pud_t *pud, unsigned long addr,
-               unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+               unsigned long end, pgprot_t prot, struct page **pages, int *nr,
+               pgtbl_mod_mask *mask)
 {
        pmd_t *pmd;
        unsigned long next;
 
-       pmd = pmd_alloc(&init_mm, pud, addr);
+       pmd = pmd_alloc_track(&init_mm, pud, addr, mask);
        if (!pmd)
                return -ENOMEM;
        do {
                next = pmd_addr_end(addr, end);
-               if (vmap_pte_range(pmd, addr, next, prot, pages, nr))
+               if (vmap_pte_range(pmd, addr, next, prot, pages, nr, mask))
                        return -ENOMEM;
        } while (pmd++, addr = next, addr != end);
        return 0;
 }
 
 static int vmap_pud_range(p4d_t *p4d, unsigned long addr,
-               unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+               unsigned long end, pgprot_t prot, struct page **pages, int *nr,
+               pgtbl_mod_mask *mask)
 {
        pud_t *pud;
        unsigned long next;
 
-       pud = pud_alloc(&init_mm, p4d, addr);
+       pud = pud_alloc_track(&init_mm, p4d, addr, mask);
        if (!pud)
                return -ENOMEM;
        do {
                next = pud_addr_end(addr, end);
-               if (vmap_pmd_range(pud, addr, next, prot, pages, nr))
+               if (vmap_pmd_range(pud, addr, next, prot, pages, nr, mask))
                        return -ENOMEM;
        } while (pud++, addr = next, addr != end);
        return 0;
 }
 
 static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
-               unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+               unsigned long end, pgprot_t prot, struct page **pages, int *nr,
+               pgtbl_mod_mask *mask)
 {
        p4d_t *p4d;
        unsigned long next;
 
-       p4d = p4d_alloc(&init_mm, pgd, addr);
+       p4d = p4d_alloc_track(&init_mm, pgd, addr, mask);
        if (!p4d)
                return -ENOMEM;
        do {
                next = p4d_addr_end(addr, end);
-               if (vmap_pud_range(p4d, addr, next, prot, pages, nr))
+               if (vmap_pud_range(p4d, addr, next, prot, pages, nr, mask))
                        return -ENOMEM;
        } while (p4d++, addr = next, addr != end);
        return 0;
@@ -255,21 +291,28 @@ static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
 int map_kernel_range_noflush(unsigned long addr, unsigned long size,
                             pgprot_t prot, struct page **pages)
 {
+       unsigned long start = addr;
        unsigned long end = addr + size;
        unsigned long next;
        pgd_t *pgd;
        int err = 0;
        int nr = 0;
+       pgtbl_mod_mask mask = 0;
 
        BUG_ON(addr >= end);
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, end);
-               err = vmap_p4d_range(pgd, addr, next, prot, pages, &nr);
+               if (pgd_bad(*pgd))
+                       mask |= PGTBL_PGD_MODIFIED;
+               err = vmap_p4d_range(pgd, addr, next, prot, pages, &nr, &mask);
                if (err)
                        return err;
        } while (pgd++, addr = next, addr != end);
 
+       if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
+               arch_sync_kernel_mappings(start, end);
+
        return 0;
 }