On Fri, Apr 29, 2016 at 02:07:54PM -0700, Yang Shi wrote:
Inspired by the counterpart of powerpc [1], which shows there is no negative effect on code generation from enabling STRICT_MM_TYPECHECKS with a modern compiler.
And, Arnd's comment [2] about that patch says STRICT_MM_TYPECHECKS could be default as long as the architecture can pass structures in registers as function arguments. ARM64 can do it as long as the size of structure <= 16 bytes. All the page table value types are u64 on ARM64.
The below disassembly demonstrates it, entry is pte_t type:
entry = arch_make_huge_pte(entry, vma, page, writable);0xffff00000826fc38 <+80>: and x0, x0, #0xfffffffffffffffd 0xffff00000826fc3c <+84>: mov w3, w21 0xffff00000826fc40 <+88>: mov x2, x20 0xffff00000826fc44 <+92>: mov x1, x19 0xffff00000826fc48 <+96>: orr x0, x0, #0x400 0xffff00000826fc4c <+100>: bl 0xffff00000809bcc0 <arch_make_huge_pte>
[1] http://www.spinics.net/lists/linux-mm/msg105951.html [2] http://www.spinics.net/lists/linux-mm/msg105969.html
Signed-off-by: Yang Shi yang.shi@linaro.org CC: Arnd Bergmann arnd@arndb.de CC: Ard Biesheuvel ard.biesheuvel@linaro.org
I'm fine with this change. If Will is still cherry-picking patches for 4.7:
Acked-by: Catalin Marinas catalin.marinas@arm.com