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[PATCH] MIPS: Refactor 'clear_page' and 'copy_page' functions.

To: linux-mips@linux-mips.org, ralf@linux-mips.org
Subject: [PATCH] MIPS: Refactor 'clear_page' and 'copy_page' functions.
From: "Steven J. Hill" <sjhill@mips.com>
Date: Thu, 24 May 2012 15:38:24 -0500
Cc: "Steven J. Hill" <sjhill@mips.com>
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From: "Steven J. Hill" <sjhill@mips.com>

Remove usage of the '__attribute__((alias("...")))' hack that aliased
to integer arrays containing micro-assembled instructions. This hack
breaks when building a microMIPS kernel. It also makes the code much
easier to understand.

Signed-off-by: Steven J. Hill <sjhill@mips.com>
---
 arch/mips/mm/Makefile     |    4 +--
 arch/mips/mm/page-funcs.S |   49 +++++++++++++++++++++++++++++++++
 arch/mips/mm/page.c       |   67 ++++++++++++---------------------------------
 3 files changed, 69 insertions(+), 51 deletions(-)
 create mode 100644 arch/mips/mm/page-funcs.S

diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index 4aa2028..fd6203f 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -3,8 +3,8 @@
 #
 
 obj-y                          += cache.o dma-default.o extable.o fault.o \
-                                  gup.o init.o mmap.o page.o tlbex.o \
-                                  tlbex-fault.o uasm.o
+                                  gup.o init.o mmap.o page.o page-funcs.o \
+                                  tlbex.o tlbex-fault.o uasm.o
 
 obj-$(CONFIG_32BIT)            += ioremap.o pgtable-32.o
 obj-$(CONFIG_64BIT)            += pgtable-64.o
diff --git a/arch/mips/mm/page-funcs.S b/arch/mips/mm/page-funcs.S
new file mode 100644
index 0000000..901c2bc
--- /dev/null
+++ b/arch/mips/mm/page-funcs.S
@@ -0,0 +1,49 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Micro-assembler generated clear_page/copy_page functions.
+ *
+ * Copyright (C) 2012  MIPS Technologies, Inc.
+ */
+#include <asm/asm.h>
+#include <asm/regdef.h>
+
+/*
+ * Maximum sizes:
+ *
+ * R4000 128 bytes S-cache:            0x058 bytes
+ * R4600 v1.7:                         0x05c bytes
+ * R4600 v2.0:                         0x060 bytes
+ * With prefetching, 16 word strides   0x120 bytes
+ */
+EXPORT(__clear_page_start)
+#ifdef CONFIG_SIBYTE_DMA_PAGEOPS
+LEAF(clear_page_cpu)
+#else
+LEAF(clear_page)
+#endif
+1:     j       1b              /* Dummy, will be replaced. */
+       .space 288
+END(clear_page)
+EXPORT(__clear_page_end)
+
+/*
+ * Maximum sizes:
+ *
+ * R4000 128 bytes S-cache:            0x11c bytes
+ * R4600 v1.7:                         0x080 bytes
+ * R4600 v2.0:                         0x07c bytes
+ * With prefetching, 16 word strides   0x540 bytes
+ */
+EXPORT(__copy_page_start)
+#ifdef CONFIG_SIBYTE_DMA_PAGEOPS
+LEAF(copy_page_cpu)
+#else
+LEAF(copy_page)
+#endif
+1:     j       1b              /* Dummy, will be replaced. */
+       .space 1344
+END(copy_page)
+EXPORT(__copy_page_end)
diff --git a/arch/mips/mm/page.c b/arch/mips/mm/page.c
index cc0b626..98f530e 100644
--- a/arch/mips/mm/page.c
+++ b/arch/mips/mm/page.c
@@ -6,6 +6,7 @@
  * Copyright (C) 2003, 04, 05 Ralf Baechle (ralf@linux-mips.org)
  * Copyright (C) 2007  Maciej W. Rozycki
  * Copyright (C) 2008  Thiemo Seufer
+ * Copyright (C) 2012  MIPS Technologies, Inc.
  */
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -71,45 +72,6 @@ static struct uasm_reloc __cpuinitdata relocs[5];
 #define cpu_is_r4600_v1_x()    ((read_c0_prid() & 0xfffffff0) == 0x00002010)
 #define cpu_is_r4600_v2_x()    ((read_c0_prid() & 0xfffffff0) == 0x00002020)
 
-/*
- * Maximum sizes:
- *
- * R4000 128 bytes S-cache:            0x058 bytes
- * R4600 v1.7:                         0x05c bytes
- * R4600 v2.0:                         0x060 bytes
- * With prefetching, 16 word strides   0x120 bytes
- */
-
-static u32 clear_page_array[0x120 / 4];
-
-#ifdef CONFIG_SIBYTE_DMA_PAGEOPS
-void clear_page_cpu(void *page) __attribute__((alias("clear_page_array")));
-#else
-void clear_page(void *page) __attribute__((alias("clear_page_array")));
-#endif
-
-EXPORT_SYMBOL(clear_page);
-
-/*
- * Maximum sizes:
- *
- * R4000 128 bytes S-cache:            0x11c bytes
- * R4600 v1.7:                         0x080 bytes
- * R4600 v2.0:                         0x07c bytes
- * With prefetching, 16 word strides   0x540 bytes
- */
-static u32 copy_page_array[0x540 / 4];
-
-#ifdef CONFIG_SIBYTE_DMA_PAGEOPS
-void
-copy_page_cpu(void *to, void *from) __attribute__((alias("copy_page_array")));
-#else
-void copy_page(void *to, void *from) __attribute__((alias("copy_page_array")));
-#endif
-
-EXPORT_SYMBOL(copy_page);
-
-
 static int pref_bias_clear_store __cpuinitdata;
 static int pref_bias_copy_load __cpuinitdata;
 static int pref_bias_copy_store __cpuinitdata;
@@ -282,10 +244,15 @@ static inline void __cpuinit build_clear_pref(u32 **buf, 
int off)
                }
 }
 
+extern u32 __clear_page_start;
+extern u32 __clear_page_end;
+extern u32 __copy_page_start;
+extern u32 __copy_page_end;
+
 void __cpuinit build_clear_page(void)
 {
        int off;
-       u32 *buf = (u32 *)&clear_page_array;
+       u32 *buf = &__clear_page_start;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;
        int i;
@@ -356,17 +323,17 @@ void __cpuinit build_clear_page(void)
        uasm_i_jr(&buf, RA);
        uasm_i_nop(&buf);
 
-       BUG_ON(buf > clear_page_array + ARRAY_SIZE(clear_page_array));
+       BUG_ON(buf > &__clear_page_end);
 
        uasm_resolve_relocs(relocs, labels);
 
        pr_debug("Synthesized clear page handler (%u instructions).\n",
-                (u32)(buf - clear_page_array));
+                (u32)(buf - &__clear_page_start));
 
        pr_debug("\t.set push\n");
        pr_debug("\t.set noreorder\n");
-       for (i = 0; i < (buf - clear_page_array); i++)
-               pr_debug("\t.word 0x%08x\n", clear_page_array[i]);
+       for (i = 0; i < (buf - &__clear_page_start); i++)
+               pr_debug("\t.word 0x%08x\n", (&__clear_page_start)[i]);
        pr_debug("\t.set pop\n");
 }
 
@@ -427,7 +394,7 @@ static inline void build_copy_store_pref(u32 **buf, int off)
 void __cpuinit build_copy_page(void)
 {
        int off;
-       u32 *buf = (u32 *)&copy_page_array;
+       u32 *buf = &__copy_page_start;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;
        int i;
@@ -595,21 +562,23 @@ void __cpuinit build_copy_page(void)
        uasm_i_jr(&buf, RA);
        uasm_i_nop(&buf);
 
-       BUG_ON(buf > copy_page_array + ARRAY_SIZE(copy_page_array));
+       BUG_ON(buf > &__copy_page_end);
 
        uasm_resolve_relocs(relocs, labels);
 
        pr_debug("Synthesized copy page handler (%u instructions).\n",
-                (u32)(buf - copy_page_array));
+                (u32)(buf - &__copy_page_start));
 
        pr_debug("\t.set push\n");
        pr_debug("\t.set noreorder\n");
-       for (i = 0; i < (buf - copy_page_array); i++)
-               pr_debug("\t.word 0x%08x\n", copy_page_array[i]);
+       for (i = 0; i < (buf - &__copy_page_start); i++)
+               pr_debug("\t.word 0x%08x\n", (&__copy_page_start)[i]);
        pr_debug("\t.set pop\n");
 }
 
 #ifdef CONFIG_SIBYTE_DMA_PAGEOPS
+extern void clear_page_cpu(void *page);
+extern void copy_page_cpu(void *to, void *from);
 
 /*
  * Pad descriptors to cacheline, since each is exclusively owned by a
-- 
1.7.10


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