[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 <gdavis@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/include/asm-arm/cacheflush.h b/include/asm-arm/cacheflush.h
index fe0c744..e4a2569 100644
--- a/include/asm-arm/cacheflush.h
+++ b/include/asm-arm/cacheflush.h
@@ -247,14 +247,12 @@
*/
#define copy_to_user_page(vma, page, vaddr, dst, src, len) \
do { \
- flush_cache_page(vma, vaddr, page_to_pfn(page));\
memcpy(dst, src, len); \
- flush_dcache_page(page); \
+ flush_ptrace_access(vma, page, vaddr, dst, len, 1);\
} while (0)
#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
do { \
- flush_cache_page(vma, vaddr, page_to_pfn(page));\
memcpy(dst, src, len); \
} while (0)
@@ -285,10 +283,24 @@
__cpuc_flush_user_range(addr, addr + PAGE_SIZE, vma->vm_flags);
}
}
+
+static inline void
+flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
+ unsigned long uaddr, void *kaddr,
+ unsigned long len, int write)
+{
+ 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);
+ }
+}
#else
extern void flush_cache_mm(struct mm_struct *mm);
extern void flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned long end);
extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr, unsigned long pfn);
+extern void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
+ unsigned long uaddr, void *kaddr,
+ unsigned long len, int write);
#endif
/*