>>> >>> I looked at that patch. >>> >>> I don't think you can just drop the #ifdef in function >>> __access_remote_vm() in mm/memory.c >>> >>> You have to replace it with something like: >>> >>> if (!IS_ENABLED(CONFIG_HAVE_IOREMAP_PROT)) >>> break; >>> >> >> >>Another thing in that patch: >> >>By making generic_access_phys() a static inline, it means that everytime >>you refer to the address of that function in a vm_operations_struct >>struct, the compiler has to provide an outlined instance of the >>function. It means you'll likely have several instances of a >>generic_access_phys(). >> >>What you could do instead is to add the following at the start of >>generic_access_phys() in mm/memory.c : >> >> if (!IS_ENABLED(CONFIG_HAVE_IOREMAP_PROT)) >> return 0; >> > >It is really a better chmoce, thanks for the advice. >Multiple instances exist as you mentioned, the block returns 0 with no-op >instance which makes no difference with the function return value. > >I will update the patch after a re-confirming. >
I tried as adviced but when not defined, error happens on archectures such as arm64. Actually the function generic_access_phys calls a lot of functions that become undefined if we compile it with CONFIG_HAVE_IOREMAP_PROT disabled. The archectures that support CONFIG_HAVE_IOREMAP_PROT are mips, x86, sh, arc, s390, loongarch and powerpc. So we may just define the function with static inline and add IS_ENABLED condition branch in function __access_remote_vm in mm/memory.c. The executing path breaks if CONFIG_HAVE_IOREMAP_PROT is disabled, and never goes into the static no-op function. In short, the static inline no-op function would never be executed, the only difference is that there would be a lot of function code in compiled target. Thanks, Wenhu
