From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Fri, 25 Dec 2015 04:40:36 +0000
Subject: initial_commit

---
 arch/arm/mm/copypage-v4mc.c | 120 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 arch/arm/mm/copypage-v4mc.c

(limited to 'arch/arm/mm/copypage-v4mc.c')

diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c
new file mode 100644
index 00000000..b8061519
--- /dev/null
+++ b/arch/arm/mm/copypage-v4mc.c
@@ -0,0 +1,120 @@
+/*
+ *  linux/arch/arm/lib/copypage-armv4mc.S
+ *
+ *  Copyright (C) 1995-2005 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This handles the mini data cache, as found on SA11x0 and XScale
+ * processors.  When we copy a user page page, we map it in such a way
+ * that accesses to this page will not touch the main data cache, but
+ * will be cached in the mini data cache.  This prevents us thrashing
+ * the main data cache on page faults.
+ */
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/cacheflush.h>
+
+#include "mm.h"
+
+/*
+ * 0xffff8000 to 0xffffffff is reserved for any ARM architecture
+ * specific hacks for copying pages efficiently.
+ */
+#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
+				  L_PTE_MT_MINICACHE)
+
+static DEFINE_SPINLOCK(minicache_lock);
+
+/*
+ * ARMv4 mini-dcache optimised copy_user_highpage
+ *
+ * We flush the destination cache lines just before we write the data into the
+ * corresponding address.  Since the Dcache is read-allocate, this removes the
+ * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
+ * and merged as appropriate.
+ *
+ * Note: We rely on all ARMv4 processors implementing the "invalidate D line"
+ * instruction.  If your processor does not supply this, you have to write your
+ * own copy_user_highpage that does the right thing.
+ */
+static void __naked
+mc_copy_user_page(void *from, void *to)
+{
+	asm volatile(
+	"stmfd	sp!, {r4, lr}			@ 2\n\
+	mov	r4, %2				@ 1\n\
+	ldmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+1:	mcr	p15, 0, %1, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%1!, {r2, r3, ip, lr}		@ 4\n\
+	ldmia	%0!, {r2, r3, ip, lr}		@ 4+1\n\
+	stmia	%1!, {r2, r3, ip, lr}		@ 4\n\
+	ldmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	mcr	p15, 0, %1, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%1!, {r2, r3, ip, lr}		@ 4\n\
+	ldmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	subs	r4, r4, #1			@ 1\n\
+	stmia	%1!, {r2, r3, ip, lr}		@ 4\n\
+	ldmneia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	bne	1b				@ 1\n\
+	ldmfd	sp!, {r4, pc}			@ 3"
+	:
+	: "r" (from), "r" (to), "I" (PAGE_SIZE / 64));
+}
+
+void v4_mc_copy_user_highpage(struct page *to, struct page *from,
+	unsigned long vaddr, struct vm_area_struct *vma)
+{
+	void *kto = kmap_atomic(to, KM_USER1);
+
+	if (!test_and_set_bit(PG_dcache_clean, &from->flags))
+		__flush_dcache_page(page_mapping(from), from);
+
+	spin_lock(&minicache_lock);
+
+	set_pte_ext(TOP_PTE(0xffff8000), pfn_pte(page_to_pfn(from), minicache_pgprot), 0);
+	flush_tlb_kernel_page(0xffff8000);
+
+	mc_copy_user_page((void *)0xffff8000, kto);
+
+	spin_unlock(&minicache_lock);
+
+	kunmap_atomic(kto, KM_USER1);
+}
+
+/*
+ * ARMv4 optimised clear_user_page
+ */
+void v4_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
+{
+	void *ptr, *kaddr = kmap_atomic(page, KM_USER0);
+	asm volatile("\
+	mov	r1, %2				@ 1\n\
+	mov	r2, #0				@ 1\n\
+	mov	r3, #0				@ 1\n\
+	mov	ip, #0				@ 1\n\
+	mov	lr, #0				@ 1\n\
+1:	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	subs	r1, r1, #1			@ 1\n\
+	bne	1b				@ 1"
+	: "=r" (ptr)
+	: "0" (kaddr), "I" (PAGE_SIZE / 64)
+	: "r1", "r2", "r3", "ip", "lr");
+	kunmap_atomic(kaddr, KM_USER0);
+}
+
+struct cpu_user_fns v4_mc_user_fns __initdata = {
+	.cpu_clear_user_highpage = v4_mc_clear_user_highpage,
+	.cpu_copy_user_highpage	= v4_mc_copy_user_highpage,
+};
-- 
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