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From: Jeff Hansen <jhansen@cardaccess-inc.com>
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Subject: [PATCH] no highpage
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On ASUS WL-500gP there are many unexpected "Segmentation fault"s that
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seem to be caused by a kernel. They can be avoided by:
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1) Disabling highpage
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2) Using flush_cache_mm in flush_cache_dup_mm
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For details see OpenWrt ticket #2035 https://dev.openwrt.org/ticket/2035
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---
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--- a/arch/mips/include/asm/page.h
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+++ b/arch/mips/include/asm/page.h
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@@ -71,6 +71,7 @@ static inline unsigned int page_size_ftl
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#endif /* CONFIG_MIPS_HUGE_TLB_SUPPORT */
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#include <linux/pfn.h>
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+#include <asm/cpu-features.h>
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extern void build_clear_page(void);
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extern void build_copy_page(void);
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@@ -105,11 +106,16 @@ static inline void clear_user_page(void
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flush_data_cache_page((unsigned long)addr);
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}
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-struct vm_area_struct;
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-extern void 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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+static inline void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
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+ struct page *to)
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+{
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+ extern void (*flush_data_cache_page)(unsigned long addr);
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-#define __HAVE_ARCH_COPY_USER_HIGHPAGE
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+ copy_page(vto, vfrom);
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+ if (!cpu_has_ic_fills_f_dc ||
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+ pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
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+ flush_data_cache_page((unsigned long)vto);
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+}
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/*
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* These are used to make use of C type-checking..
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--- a/arch/mips/mm/init.c
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+++ b/arch/mips/mm/init.c
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@@ -154,30 +154,6 @@ void kunmap_coherent(void)
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pagefault_enable();
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}
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-void 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 *vfrom, *vto;
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-
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- vto = kmap_atomic(to);
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- if (cpu_has_dc_aliases && cpu_use_kmap_coherent &&
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- page_mapped(from) && !Page_dcache_dirty(from)) {
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- vfrom = kmap_coherent(from, vaddr);
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- copy_page(vto, vfrom);
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- kunmap_coherent();
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- } else {
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- vfrom = kmap_atomic(from);
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- copy_page(vto, vfrom);
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- kunmap_atomic(vfrom);
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- }
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- if ((!cpu_has_ic_fills_f_dc) ||
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- pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
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- flush_data_cache_page((unsigned long)vto);
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- kunmap_atomic(vto);
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- /* Make sure this page is cleared on other CPU's too before using it */
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- smp_wmb();
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-}
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-
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void copy_to_user_page(struct vm_area_struct *vma,
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struct page *page, unsigned long vaddr, void *dst, const void *src,
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unsigned long len)
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