arm64: always use STRICT_MM_TYPECHECKS
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
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
1 file changed