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MIPS: Refactor 'clear_page' and 'copy_page' functions.
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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.

[ralf@linux-mips.org: Added back export of the clear_page and copy_page
symbols so certain modules will work again.  Also fixed build with
CONFIG_SIBYTE_DMA_PAGEOPS enabled.]

Signed-off-by: Steven J. Hill <sjhill@mips.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3866/
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Steven J. Hill authored and Ralf Baechle committed Jul 19, 2012
1 parent 78d4803 commit c022630
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Showing 4 changed files with 77 additions and 52 deletions.
8 changes: 7 additions & 1 deletion arch/mips/kernel/mips_ksyms.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996, 97, 98, 99, 2000, 01, 03, 04, 05 by Ralf Baechle
* Copyright (C) 1996, 97, 98, 99, 2000, 01, 03, 04, 05, 12 by Ralf Baechle
* Copyright (C) 1999, 2000, 01 Silicon Graphics, Inc.
*/
#include <linux/interrupt.h>
Expand Down Expand Up @@ -34,6 +34,12 @@ EXPORT_SYMBOL(memmove);

EXPORT_SYMBOL(kernel_thread);

/*
* Functions that operate on entire pages. Mostly used by memory management.
*/
EXPORT_SYMBOL(clear_page);
EXPORT_SYMBOL(copy_page);

/*
* Userspace access stuff.
*/
Expand Down
4 changes: 2 additions & 2 deletions arch/mips/mm/Makefile
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Expand Up @@ -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
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50 changes: 50 additions & 0 deletions arch/mips/mm/page-funcs.S
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@@ -0,0 +1,50 @@
/*
* 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.
* Copyright (C) 2012 Ralf Baechle <ralf@linux-mips.org>
*/
#include <asm/asm.h>
#include <asm/regdef.h>

#ifdef CONFIG_SIBYTE_DMA_PAGEOPS
#define cpu_clear_page_function_name clear_page_cpu
#define cpu_copy_page_function_name copy_page_cpu
#else
#define cpu_clear_page_function_name clear_page
#define cpu_copy_page_function_name copy_page
#endif

/*
* 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)
LEAF(cpu_clear_page_function_name)
1: j 1b /* Dummy, will be replaced. */
.space 288
END(cpu_clear_page_function_name)
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)
LEAF(cpu_copy_page_function_name)
1: j 1b /* Dummy, will be replaced. */
.space 1344
END(cpu_copy_page_function_name)
EXPORT(__copy_page_end)
67 changes: 18 additions & 49 deletions arch/mips/mm/page.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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");
}

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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
Expand Down

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