On Fri, Feb 14, 2025 at 10:49:01AM +0800, Tong Tiangen wrote: > 在 2025/2/13 1:11, Catalin Marinas 写道: > > On Mon, Dec 09, 2024 at 10:42:56AM +0800, Tong Tiangen wrote: > > > Currently, many scenarios that can tolerate memory errors when copying page > > > have been supported in the kernel[1~5], all of which are implemented by > > > copy_mc_[user]_highpage(). arm64 should also support this mechanism. > > > > > > Due to mte, arm64 needs to have its own copy_mc_[user]_highpage() > > > architecture implementation, macros __HAVE_ARCH_COPY_MC_HIGHPAGE and > > > __HAVE_ARCH_COPY_MC_USER_HIGHPAGE have been added to control it. > > > > > > Add new helper copy_mc_page() which provide a page copy implementation with > > > hardware memory error safe. The code logic of copy_mc_page() is the same as > > > copy_page(), the main difference is that the ldp insn of copy_mc_page() > > > contains the fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR, therefore, the > > > main logic is extracted to copy_page_template.S. In addition, the fixup of > > > MOPS insn is not considered at present. > > > > Could we not add the exception table entry permanently but ignore the > > exception table entry if it's not on the do_sea() path? That would save > > some code duplication. > > I'm sorry, I didn't catch your point, that the do_sea() and non do_sea() > paths use different exception tables? No, they would have the same exception table, only that we'd interpret it differently depending on whether it's a SEA error or not. Or rather ignore the exception table altogether for non-SEA errors. > My understanding is that the > exception table entry problem is fine. After all, the search is > performed only after a fault trigger. Code duplication can be solved by > extracting repeated logic to a public file. If the new exception table entries are only taken into account for SEA errors, why do we need a duplicate copy_mc_page() function generated? Isn't the copy_page() and copy_mc_page() code identical (except for the additional labels to jump to for the exception)? -- Catalin
