sh: Rework sh4_flush_cache_page() for coherent kmap mapping.

This builds on top of the MIPS r4k code that does roughly the same thing.
This permits the use of kmap_coherent() for mapped pages with dirty
dcache lines and falls back on kmap_atomic() otherwise.

This also fixes up a problem with the alias check and defers to
shm_align_mask directly.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 48 insertions, 27 deletions

diff --git a/arch/sh/mm/cache-sh4.c b/arch/sh/mm/cache-sh4.c
index 92b7d947db94..e3fbd99b323c 100644
--- a/arch/sh/mm/cache-sh4.c
+++ b/arch/sh/mm/cache-sh4.c
@@ -2,7 +2,7 @@
  * arch/sh/mm/cache-sh4.c
  *
  * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
- * Copyright (C) 2001 - 2007  Paul Mundt
+ * Copyright (C) 2001 - 2009  Paul Mundt
  * Copyright (C) 2003  Richard Curnow
  * Copyright (c) 2007 STMicroelectronics (R&D) Ltd.
  *
@@ -15,6 +15,8 @@
 #include <linux/io.h>
 #include <linux/mutex.h>
 #include <linux/fs.h>
+#include <linux/highmem.h>
+#include <asm/pgtable.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 
@@ -23,7 +25,6 @@
  * flushing. Anything exceeding this will simply flush the dcache in its
  * entirety.
  */
-#define MAX_DCACHE_PAGES        64      /* XXX: Tune for ways */
 #define MAX_ICACHE_PAGES        32
 
 static void __flush_cache_4096(unsigned long addr, unsigned long phys,
@@ -209,44 +210,64 @@ static void sh4_flush_cache_page(void *args)
 {
         struct flusher_data *data = args;
         struct vm_area_struct *vma;
+        struct page *page;
         unsigned long address, pfn, phys;
-        unsigned int alias_mask;
+        int map_coherent = 0;
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
+        void *vaddr;
 
         vma = data->vma;
         address = data->addr1;
         pfn = data->addr2;
         phys = pfn << PAGE_SHIFT;
+        page = pfn_to_page(pfn);
 
         if (cpu_context(smp_processor_id(), vma->vm_mm) == NO_CONTEXT)
                 return;
 
-        alias_mask = boot_cpu_data.dcache.alias_mask;
-
-        /* We only need to flush D-cache when we have alias */
-        if ((address^phys) & alias_mask) {
-                /* Loop 4K of the D-cache */
-                flush_cache_4096(
-                        CACHE_OC_ADDRESS_ARRAY | (address & alias_mask),
-                        phys);
-                /* Loop another 4K of the D-cache */
-                flush_cache_4096(
-                        CACHE_OC_ADDRESS_ARRAY | (phys & alias_mask),
-                        phys);
-        }
+        address &= PAGE_MASK;
+        pgd = pgd_offset(vma->vm_mm, address);
+        pud = pud_offset(pgd, address);
+        pmd = pmd_offset(pud, address);
+        pte = pte_offset_kernel(pmd, address);
+
+        /* If the page isn't present, there is nothing to do here. */
+        if (!(pte_val(*pte) & _PAGE_PRESENT))
+                return;
 
-        alias_mask = boot_cpu_data.icache.alias_mask;
-        if (vma->vm_flags & VM_EXEC) {
+        if ((vma->vm_mm == current->active_mm))
+                vaddr = NULL;
+        else {
                 /*
-                 * Evict entries from the portion of the cache from which code
-                 * may have been executed at this address (virtual).  There's
-                 * no need to evict from the portion corresponding to the
-                 * physical address as for the D-cache, because we know the
-                 * kernel has never executed the code through its identity
-                 * translation.
+                 * Use kmap_coherent or kmap_atomic to do flushes for
+                 * another ASID than the current one.
                  */
-                flush_cache_4096(
-                        CACHE_IC_ADDRESS_ARRAY | (address & alias_mask),
-                        phys);
+                map_coherent = (current_cpu_data.dcache.n_aliases &&
+                        !test_bit(PG_dcache_dirty, &page->flags) &&
+                        page_mapped(page));
+                if (map_coherent)
+                        vaddr = kmap_coherent(page, address);
+                else
+                        vaddr = kmap_atomic(page, KM_USER0);
+
+                address = (unsigned long)vaddr;
+        }
+
+        if (pages_do_alias(address, phys))
+                flush_cache_4096(CACHE_OC_ADDRESS_ARRAY |
+                        (address & shm_align_mask), phys);
+
+        if (vma->vm_flags & VM_EXEC)
+                flush_icache_all();
+
+        if (vaddr) {
+                if (map_coherent)
+                        kunmap_coherent(vaddr);
+                else
+                        kunmap_atomic(vaddr, KM_USER0);
         }
 }