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From: Jeff Hansen <jhansen@cardaccess-inc.com>
Subject: [PATCH] no highpage
On ASUS WL-500gP there are many unexpected "Segmentation fault"s that
seem to be caused by a kernel. They can be avoided by:
1) Disabling highpage
2) Using flush_cache_mm in flush_cache_dup_mm
For details see OpenWrt ticket #2035 https://dev.openwrt.org/ticket/2035
---
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -71,6 +71,7 @@ static inline unsigned int page_size_ftl
#endif /* CONFIG_MIPS_HUGE_TLB_SUPPORT */
#include <linux/pfn.h>
+#include <asm/cpu-features.h>
extern void build_clear_page(void);
extern void build_copy_page(void);
@@ -105,11 +106,16 @@ static inline void clear_user_page(void
flush_data_cache_page((unsigned long)addr);
}
-struct vm_area_struct;
-extern void copy_user_highpage(struct page *to, struct page *from,
- unsigned long vaddr, struct vm_area_struct *vma);
+static inline void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
+ struct page *to)
+{
+ extern void (*flush_data_cache_page)(unsigned long addr);
-#define __HAVE_ARCH_COPY_USER_HIGHPAGE
+ copy_page(vto, vfrom);
+ if (!cpu_has_ic_fills_f_dc ||
+ pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
+ flush_data_cache_page((unsigned long)vto);
+}
/*
* These are used to make use of C type-checking..
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -158,30 +158,6 @@ void kunmap_coherent(void)
preempt_enable();
}
-void copy_user_highpage(struct page *to, struct page *from,
- unsigned long vaddr, struct vm_area_struct *vma)
-{
- void *vfrom, *vto;
-
- vto = kmap_atomic(to);
- if (cpu_has_dc_aliases && cpu_use_kmap_coherent &&
- page_mapped(from) && !Page_dcache_dirty(from)) {
- vfrom = kmap_coherent(from, vaddr);
- copy_page(vto, vfrom);
- kunmap_coherent();
- } else {
- vfrom = kmap_atomic(from);
- copy_page(vto, vfrom);
- kunmap_atomic(vfrom);
- }
- if ((!cpu_has_ic_fills_f_dc) ||
- pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
- flush_data_cache_page((unsigned long)vto);
- kunmap_atomic(vto);
- /* Make sure this page is cleared on other CPU's too before using it */
- smp_wmb();
-}
-
void copy_to_user_page(struct vm_area_struct *vma,
struct page *page, unsigned long vaddr, void *dst, const void *src,
unsigned long len)
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