// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/arch/arm/lib/copypage-armv4mc.S
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*
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* Copyright (C) 1995-2005 Russell King
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*
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* This handles the mini data cache, as found on SA11x0 and XScale
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* processors. When we copy a user page page, we map it in such a way
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* that accesses to this page will not touch the main data cache, but
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* will be cached in the mini data cache. This prevents us thrashing
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* the main data cache on page faults.
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*/
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <asm/tlbflush.h>
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#include <asm/cacheflush.h>
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#include "mm.h"
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#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
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L_PTE_MT_MINICACHE)
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static DEFINE_RAW_SPINLOCK(minicache_lock);
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/*
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* ARMv4 mini-dcache optimised copy_user_highpage
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*
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* We flush the destination cache lines just before we write the data into the
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* corresponding address. Since the Dcache is read-allocate, this removes the
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* Dcache aliasing issue. The writes will be forwarded to the write buffer,
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* and merged as appropriate.
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*
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* Note: We rely on all ARMv4 processors implementing the "invalidate D line"
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* instruction. If your processor does not supply this, you have to write your
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* own copy_user_highpage that does the right thing.
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*/
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static void mc_copy_user_page(void *from, void *to)
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{
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int tmp;
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asm volatile ("\
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.syntax unified\n\
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ldmia %0!, {r2, r3, ip, lr} @ 4\n\
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1: mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\
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stmia %1!, {r2, r3, ip, lr} @ 4\n\
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ldmia %0!, {r2, r3, ip, lr} @ 4+1\n\
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stmia %1!, {r2, r3, ip, lr} @ 4\n\
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ldmia %0!, {r2, r3, ip, lr} @ 4\n\
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mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\
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stmia %1!, {r2, r3, ip, lr} @ 4\n\
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ldmia %0!, {r2, r3, ip, lr} @ 4\n\
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subs %2, %2, #1 @ 1\n\
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stmia %1!, {r2, r3, ip, lr} @ 4\n\
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ldmiane %0!, {r2, r3, ip, lr} @ 4\n\
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bne 1b @ "
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: "+&r" (from), "+&r" (to), "=&r" (tmp)
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: "2" (PAGE_SIZE / 64)
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: "r2", "r3", "ip", "lr");
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}
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void v4_mc_copy_user_highpage(struct page *to, struct page *from,
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unsigned long vaddr, struct vm_area_struct *vma)
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{
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void *kto = kmap_atomic(to);
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if (!test_and_set_bit(PG_dcache_clean, &from->flags))
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__flush_dcache_page(page_mapping_file(from), from);
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raw_spin_lock(&minicache_lock);
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set_top_pte(COPYPAGE_MINICACHE, mk_pte(from, minicache_pgprot));
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mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
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raw_spin_unlock(&minicache_lock);
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kunmap_atomic(kto);
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}
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/*
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* ARMv4 optimised clear_user_page
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*/
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void v4_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
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{
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void *ptr, *kaddr = kmap_atomic(page);
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asm volatile("\
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mov r1, %2 @ 1\n\
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mov r2, #0 @ 1\n\
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mov r3, #0 @ 1\n\
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mov ip, #0 @ 1\n\
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mov lr, #0 @ 1\n\
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1: mcr p15, 0, %0, c7, c6, 1 @ 1 invalidate D line\n\
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stmia %0!, {r2, r3, ip, lr} @ 4\n\
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stmia %0!, {r2, r3, ip, lr} @ 4\n\
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mcr p15, 0, %0, c7, c6, 1 @ 1 invalidate D line\n\
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stmia %0!, {r2, r3, ip, lr} @ 4\n\
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stmia %0!, {r2, r3, ip, lr} @ 4\n\
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subs r1, r1, #1 @ 1\n\
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bne 1b @ 1"
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: "=r" (ptr)
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: "0" (kaddr), "I" (PAGE_SIZE / 64)
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: "r1", "r2", "r3", "ip", "lr");
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kunmap_atomic(kaddr);
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}
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struct cpu_user_fns v4_mc_user_fns __initdata = {
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.cpu_clear_user_highpage = v4_mc_clear_user_highpage,
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.cpu_copy_user_highpage = v4_mc_copy_user_highpage,
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};
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