[XTENSA] Add support for cache-aliasing

Add support for processors that have cache-aliasing issues, such as
the Stretch S5000 processor. Cache-aliasing means that the size of
the cache (for one way) is larger than the page size, thus, a page
can end up in several places in cache depending on the virtual to
physical translation. The method used here is to map a user page
temporarily through the auto-refill way 0 and of of the DTLB.
We probably will want to revisit this issue and use a better
approach with kmap/kunmap.

Signed-off-by: Chris Zankel <chris@zankel.net>

1 files changed, 271 insertions, 35 deletions

diff --git a/arch/xtensa/mm/misc.S b/arch/xtensa/mm/misc.S
index ae085332c607..e1f880368e32 100644
--- a/arch/xtensa/mm/misc.S
+++ b/arch/xtensa/mm/misc.S
@@ -7,29 +7,33 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * Copyright (C) 2001 - 2005 Tensilica Inc.
+ * Copyright (C) 2001 - 2007 Tensilica Inc.
  *
  * Chris Zankel <chris@zankel.net>
  */
 
-/* Note: we might want to implement some of the loops as zero-overhead-loops,
- *       where applicable and if supported by the processor.
- */
 
 #include <linux/linkage.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/asmmacro.h>
 #include <asm/cacheasm.h>
+#include <asm/tlbflush.h>
+
 
-/* clear_page (page) */
+/*
+ * clear_page and clear_user_page are the same for non-cache-aliased configs.
+ *
+ * clear_page (unsigned long page)
+ *                    a2
+ */
 
 ENTRY(clear_page)
         entry   a1, 16
-        addi    a4, a2, PAGE_SIZE
-        movi    a3, 0
 
-1:      s32i    a3, a2, 0
+        movi    a3, 0
+        __loopi a2, a7, PAGE_SIZE, 32
+        s32i    a3, a2, 0
         s32i    a3, a2, 4
         s32i    a3, a2, 8
         s32i    a3, a2, 12
@@ -37,42 +41,277 @@ ENTRY(clear_page)
         s32i    a3, a2, 20
         s32i    a3, a2, 24
         s32i    a3, a2, 28
-        addi    a2, a2, 32
-        blt     a2, a4, 1b
+        __endla a2, a7, 32
 
         retw
 
 /*
+ * copy_page and copy_user_page are the same for non-cache-aliased configs.
+ *
  * copy_page (void *to, void *from)
- *                  a2        a3
+ *               a2          a3
  */
 
 ENTRY(copy_page)
         entry   a1, 16
-        addi    a4, a2, PAGE_SIZE
-
-1:      l32i    a5, a3, 0
-        l32i    a6, a3, 4
-        l32i    a7, a3, 8
-        s32i    a5, a2, 0
-        s32i    a6, a2, 4
-        s32i    a7, a2, 8
-        l32i    a5, a3, 12
-        l32i    a6, a3, 16
-        l32i    a7, a3, 20
-        s32i    a5, a2, 12
-        s32i    a6, a2, 16
-        s32i    a7, a2, 20
-        l32i    a5, a3, 24
-        l32i    a6, a3, 28
-        s32i    a5, a2, 24
-        s32i    a6, a2, 28
-        addi    a2, a2, 32
-        addi    a3, a3, 32
-        blt     a2, a4, 1b
 
+        __loopi a2, a4, PAGE_SIZE, 32
+
+        l32i    a8, a3, 0
+        l32i    a9, a3, 4
+        s32i    a8, a2, 0
+        s32i    a9, a2, 4
+
+        l32i    a8, a3, 8
+        l32i    a9, a3, 12
+        s32i    a8, a2, 8
+        s32i    a9, a2, 12
+
+        l32i    a8, a3, 16
+        l32i    a9, a3, 20
+        s32i    a8, a2, 16
+        s32i    a9, a2, 20
+
+        l32i    a8, a3, 24
+        l32i    a9, a3, 28
+        s32i    a8, a2, 24
+        s32i    a9, a2, 28
+
+        addi    a2, a2, 32
+        addi    a3, a3, 32
+
+        __endl  a2, a4
+
+        retw
+
+/*
+ * If we have to deal with cache aliasing, we use temporary memory mappings
+ * to ensure that the source and destination pages have the same color as
+ * the virtual address. We use way 0 and 1 for temporary mappings in such cases.
+ *
+ * The temporary DTLB entries shouldn't be flushed by interrupts, but are
+ * flushed by preemptive task switches. Special code in the 
+ * fast_second_level_miss handler re-established the temporary mapping. 
+ * It requires that the PPNs for the destination and source addresses are
+ * in a6, and a7, respectively.
+ */
+
+/* TLB miss exceptions are treated special in the following region */
+
+ENTRY(__tlbtemp_mapping_start)
+
+#if (DCACHE_WAY_SIZE > PAGE_SIZE)
+
+/*
+ * clear_user_page (void *addr, unsigned long vaddr, struct page *page)
+ *                     a2              a3                 a4
+ */
+
+ENTRY(clear_user_page)
+        entry   a1, 32
+
+        /* Mark page dirty and determine alias. */
+
+        movi    a7, (1 << PG_ARCH_1)
+        l32i    a5, a4, PAGE_FLAGS
+        xor     a6, a2, a3
+        extui   a3, a3, PAGE_SHIFT, DCACHE_ALIAS_ORDER
+        extui   a6, a6, PAGE_SHIFT, DCACHE_ALIAS_ORDER
+        or      a5, a5, a7
+        slli    a3, a3, PAGE_SHIFT
+        s32i    a5, a4, PAGE_FLAGS
+
+        /* Skip setting up a temporary DTLB if not aliased. */
+
+        beqz    a6, 1f
+
+        /* Invalidate kernel page. */
+
+        mov     a10, a2
+        call8   __invalidate_dcache_page
+
+        /* Setup a temporary DTLB with the color of the VPN */
+
+        movi    a4, -PAGE_OFFSET + (PAGE_KERNEL | _PAGE_HW_WRITE)
+        movi    a5, TLBTEMP_BASE_1                      # virt
+        add     a6, a2, a4                              # ppn
+        add     a2, a5, a3                              # add 'color'
+
+        wdtlb   a6, a2
+        dsync
+
+1:      movi    a3, 0
+        __loopi a2, a7, PAGE_SIZE, 32
+        s32i    a3, a2, 0
+        s32i    a3, a2, 4
+        s32i    a3, a2, 8
+        s32i    a3, a2, 12
+        s32i    a3, a2, 16
+        s32i    a3, a2, 20
+        s32i    a3, a2, 24
+        s32i    a3, a2, 28
+        __endla a2, a7, 32
+
+        bnez    a6, 1f
+        retw
+
+        /* We need to invalidate the temporary idtlb entry, if any. */
+
+1:      addi    a2, a2, -PAGE_SIZE
+        idtlb   a2
+        dsync
+
+        retw
+
+/*
+ * copy_page_user (void *to, void *from, unsigned long vaddr, struct page *page)
+ *                    a2          a3            a4                  a5
+ */
+
+ENTRY(copy_user_page)
+
+        entry   a1, 32 
+
+        /* Mark page dirty and determine alias for destination. */
+
+        movi    a8, (1 << PG_ARCH_1)
+        l32i    a9, a5, PAGE_FLAGS
+        xor     a6, a2, a4
+        xor     a7, a3, a4
+        extui   a4, a4, PAGE_SHIFT, DCACHE_ALIAS_ORDER
+        extui   a6, a6, PAGE_SHIFT, DCACHE_ALIAS_ORDER
+        extui   a7, a7, PAGE_SHIFT, DCACHE_ALIAS_ORDER
+        or      a9, a9, a8
+        slli    a4, a4, PAGE_SHIFT
+        s32i    a9, a5, PAGE_FLAGS
+        movi    a5, -PAGE_OFFSET + (PAGE_KERNEL | _PAGE_HW_WRITE)
+
+        beqz    a6, 1f
+
+        /* Invalidate dcache */
+
+        mov     a10, a2
+        call8   __invalidate_dcache_page
+
+        /* Setup a temporary DTLB with a matching color. */
+
+        movi    a8, TLBTEMP_BASE_1                      # base
+        add     a6, a2, a5                              # ppn
+        add     a2, a8, a4                              # add 'color'
+
+        wdtlb   a6, a2
+        dsync
+
+        /* Skip setting up a temporary DTLB for destination if not aliased. */
+
+1:      beqz    a7, 1f
+
+        /* Setup a temporary DTLB with a matching color. */
+
+        movi    a8, TLBTEMP_BASE_2                      # base
+        add     a7, a3, a5                              # ppn
+        add     a3, a8, a4
+        addi    a8, a3, 1                               # way1
+
+        wdtlb   a7, a8
+        dsync
+
+1:      __loopi a2, a4, PAGE_SIZE, 32
+
+        l32i    a8, a3, 0
+        l32i    a9, a3, 4
+        s32i    a8, a2, 0
+        s32i    a9, a2, 4
+
+        l32i    a8, a3, 8
+        l32i    a9, a3, 12
+        s32i    a8, a2, 8
+        s32i    a9, a2, 12
+
+        l32i    a8, a3, 16
+        l32i    a9, a3, 20
+        s32i    a8, a2, 16
+        s32i    a9, a2, 20
+
+        l32i    a8, a3, 24
+        l32i    a9, a3, 28
+        s32i    a8, a2, 24
+        s32i    a9, a2, 28
+
+        addi    a2, a2, 32
+        addi    a3, a3, 32
+
+        __endl  a2, a4
+
+        /* We need to invalidate any temporary mapping! */
+
+        bnez    a6, 1f
+        bnez    a7, 2f
+        retw
+
+1:      addi    a2, a2, -PAGE_SIZE
+        idtlb   a2
+        dsync
+        bnez    a7, 2f
+        retw
+
+2:      addi    a3, a3, -PAGE_SIZE+1
+        idtlb   a3
+        dsync
+
+        retw
+
+#endif
+
+#if (DCACHE_WAY_SIZE > PAGE_SIZE)
+
+/*
+ * void __flush_invalidate_dcache_page_alias (addr, phys)
+ *                                             a2    a3
+ */
+
+ENTRY(__flush_invalidate_dcache_page_alias)
+        entry   sp, 16
+
+        movi    a7, 0                   # required for exception handler
+        addi    a6, a3, (PAGE_KERNEL | _PAGE_HW_WRITE)
+        mov     a4, a2
+        wdtlb   a6, a2
+        dsync
+
+        ___flush_invalidate_dcache_page a2 a3
+
+        idtlb   a4
+        dsync
+
+        retw
+
+#endif
+
+ENTRY(__tlbtemp_mapping_itlb)
+
+#if (ICACHE_WAY_SIZE > PAGE_SIZE)
+        
+ENTRY(__invalidate_icache_page_alias)
+        entry   sp, 16
+
+        addi    a6, a3, (PAGE_KERNEL | _PAGE_HW_WRITE)
+        mov     a4, a2
+        witlb   a6, a2
+        isync
+
+        ___invalidate_icache_page a2 a3
+
+        iitlb   a4
+        isync
         retw
 
+#endif
+
+/* End of special treatment in tlb miss exception */
+
+ENTRY(__tlbtemp_mapping_end)
+
 /*
  * void __invalidate_icache_page(ulong start)
  */
@@ -121,8 +360,6 @@ ENTRY(__flush_dcache_page)
         dsync
         retw
 
-
-
 /*
  * void __invalidate_icache_range(ulong start, ulong size)
  */
@@ -168,7 +405,6 @@ ENTRY(__invalidate_dcache_range)
 
         ___invalidate_dcache_range a2 a3 a4
 
-
         retw
 
 /*