From a188ad2bc7dbfa16ccdcaa8d43ade185b969baff Mon Sep 17 00:00:00 2001 From: "George G. Davis" Date: Sat, 2 Sep 2006 18:43:20 +0100 Subject: [ARM] 3762/1: Fix ptrace cache coherency bug for ARM1136 VIPT nonaliasing Harvard caches Patch from George G. Davis Resolve ARM1136 VIPT non-aliasing cache coherency issues observed when using ptrace to set breakpoints and cleanup copy_{to,from}_user_page() while we're here as requested by Russell King because "it's also far too heavy on non-v6 CPUs". NOTES: 1. Only access_process_vm() calls copy_{to,from}_user_page(). 2. access_process_vm() calls get_user_pages() to pin down the "page". 3. get_user_pages() calls flush_dcache_page(page) which ensures cache coherency between kernel and userspace mappings of "page". However flush_dcache_page(page) may not invalidate I-Cache over this range for all cases, specifically, I-Cache is not invalidated for the VIPT non-aliasing case. So memory is consistent between kernel and user space mappings of "page" but I-Cache may still be hot over this range. IOW, we don't have to worry about flush_cache_page() before memcpy(). 4. Now, for the copy_to_user_page() case, after memcpy(), we must flush the caches so memory is consistent with kernel cache entries and invalidate the I-Cache if this mm region is executable. We don't need to do anything after memcpy() for the copy_from_user_page() case since kernel cache entries will be invalidated via the same process above if we access "page" again. The flush_ptrace_access() function (borrowed from SPARC64 implementation) is added to handle cache flushing after memcpy() for the copy_to_user_page() case. Signed-off-by: George G. Davis Signed-off-by: Russell King --- arch/arm/mm/flush.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'arch/arm') diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index b103e56806b..d438ce41cdd 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -87,6 +87,32 @@ void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr, unsig if (cache_is_vipt_aliasing()) flush_pfn_alias(pfn, user_addr); } + +void flush_ptrace_access(struct vm_area_struct *vma, struct page *page, + unsigned long uaddr, void *kaddr, + unsigned long len, int write) +{ + if (cache_is_vivt()) { + if (cpu_isset(smp_processor_id(), vma->vm_mm->cpu_vm_mask)) { + unsigned long addr = (unsigned long)kaddr; + __cpuc_coherent_kern_range(addr, addr + len); + } + return; + } + + if (cache_is_vipt_aliasing()) { + flush_pfn_alias(page_to_pfn(page), uaddr); + return; + } + + /* VIPT non-aliasing cache */ + if (cpu_isset(smp_processor_id(), vma->vm_mm->cpu_vm_mask) && + vma->vm_flags | VM_EXEC) { + unsigned long addr = (unsigned long)kaddr; + /* only flushing the kernel mapping on non-aliasing VIPT */ + __cpuc_coherent_kern_range(addr, addr + len); + } +} #else #define flush_pfn_alias(pfn,vaddr) do { } while (0) #endif -- cgit v1.2.3