On Tue, Mar 01, 2016 at 02:37:57AM +0000, Paul Burton wrote: > When flush_dcache_page is called on an executable page, that page is > about to be provided to userland & we can presume that the icache > contains no valid entries for its address range. However if the icache > does not fill from the dcache then we cannot presume that the pages > content has been written back as far as the memories that the dcache > will fill from (ie. L2 or further out). > > This was being done for lowmem pages, but not for highmem which can lead > to icache corruption. Fix this by mapping highmem pages & flushing their > content from the dcache in __flush_dcache_page before providing the page > to userland, just as is done for lowmem pages. > > Signed-off-by: Paul Burton <[email protected]> > Cc: Lars Persson <[email protected]> > --- > > arch/mips/mm/cache.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c > index 3f159ca..5a67d8c 100644 > --- a/arch/mips/mm/cache.c > +++ b/arch/mips/mm/cache.c > @@ -16,6 +16,7 @@ > #include <linux/mm.h> > > #include <asm/cacheflush.h> > +#include <asm/highmem.h> > #include <asm/processor.h> > #include <asm/cpu.h> > #include <asm/cpu-features.h> > @@ -83,8 +84,6 @@ void __flush_dcache_page(struct page *page) > struct address_space *mapping = page_mapping(page); > unsigned long addr; > > - if (PageHighMem(page)) > - return; > if (mapping && !mapping_mapped(mapping)) { > SetPageDcacheDirty(page); > return; > @@ -95,8 +94,15 @@ void __flush_dcache_page(struct page *page) > * case is for exec env/arg pages and those are %99 certainly going to > * get faulted into the tlb (and thus flushed) anyways. > */ > - addr = (unsigned long) page_address(page); > + if (PageHighMem(page)) > + addr = (unsigned long)kmap_atomic(page); > + else > + addr = (unsigned long)page_address(page); > + > flush_data_cache_page(addr); > + > + if (PageHighMem(page)) > + __kunmap_atomic((void *)addr); > } > > EXPORT_SYMBOL(__flush_dcache_page);
I don't see how this should work with cache aliases. If the page is unmapped kmap_atomic will pick a deterministic address only under some circumstances, kmap won't. As the result the wrong cache way will be flushed out, I think. Ralf
