From: Jeff Hansen 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 +#include extern void build_clear_page(void); extern void build_copy_page(void); @@ -110,11 +111,16 @@ 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 @@ -166,30 +166,6 @@ 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_mapcount(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)