xtensa: support aliasing cache in k[un]map_atomic

Map high memory pages at virtual addresses with color that match color
of their physical address. Existing cache alias management mechanisms
may be used with such pages.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

3 files changed, 14 insertions, 8 deletions

diff --git a/arch/xtensa/include/asm/fixmap.h b/arch/xtensa/include/asm/fixmap.h
index a43cd5265556..62b507deea9d 100644
--- a/arch/xtensa/include/asm/fixmap.h
+++ b/arch/xtensa/include/asm/fixmap.h
@@ -38,7 +38,8 @@ enum fixed_addresses {
 #ifdef CONFIG_HIGHMEM
         /* reserved pte's for temporary kernel mappings */
         FIX_KMAP_BEGIN,
-        FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
+        FIX_KMAP_END = FIX_KMAP_BEGIN +
+                (KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1,
 #endif
         __end_of_fixed_addresses
 };
diff --git a/arch/xtensa/include/asm/page.h b/arch/xtensa/include/asm/page.h
index 11721ccd7f23..abe24c6f8b2f 100644
--- a/arch/xtensa/include/asm/page.h
+++ b/arch/xtensa/include/asm/page.h
@@ -78,7 +78,9 @@
 # define DCACHE_ALIAS_EQ(a,b)   ((((a) ^ (b)) & DCACHE_ALIAS_MASK) == 0)
 #else
 # define DCACHE_ALIAS_ORDER     0
+# define DCACHE_ALIAS(a)        ((void)(a), 0)
 #endif
+#define DCACHE_N_COLORS         (1 << DCACHE_ALIAS_ORDER)
 
 #if ICACHE_WAY_SIZE > PAGE_SIZE
 # define ICACHE_ALIAS_ORDER     (ICACHE_WAY_SHIFT - PAGE_SHIFT)
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 2e95a7665bf3..466abaed5382 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -14,18 +14,23 @@
 
 static pte_t *kmap_pte;
 
+static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
+{
+        return (type + KM_TYPE_NR * smp_processor_id()) * DCACHE_N_COLORS +
+                color;
+}
+
 void *kmap_atomic(struct page *page)
 {
         enum fixed_addresses idx;
         unsigned long vaddr;
-        int type;
 
         pagefault_disable();
         if (!PageHighMem(page))
                 return page_address(page);
 
-        type = kmap_atomic_idx_push();
-        idx = type + KM_TYPE_NR * smp_processor_id();
+        idx = kmap_idx(kmap_atomic_idx_push(),
+                       DCACHE_ALIAS(page_to_phys(page)));
         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
         BUG_ON(!pte_none(*(kmap_pte + idx)));
@@ -38,12 +43,10 @@ EXPORT_SYMBOL(kmap_atomic);
 
 void __kunmap_atomic(void *kvaddr)
 {
-        int idx, type;
-
         if (kvaddr >= (void *)FIXADDR_START &&
             kvaddr < (void *)FIXADDR_TOP) {
-                type = kmap_atomic_idx();
-                idx = type + KM_TYPE_NR * smp_processor_id();
+                int idx = kmap_idx(kmap_atomic_idx(),
+                                   DCACHE_ALIAS((unsigned long)kvaddr));
 
                 /*
                  * Force other mappings to Oops if they'll try to access this