On Mon, Jan 23, 2017 at 12:59 PM, Matthew Wilcox <willy6545@xxxxxxxxx> wrote: > Why put it in the user address space? As I said earlier in this thread, we > want the facility to run code from kernel addresses in user mode, limited to > only being able to access its own stack and the user addresses. Of course it > should also be able to make syscalls, like mmap. Would you believe I've already started prototyping this (the kernel-code-in-user-mode part, not the execve part)? As a practical matter, though, I think the implementation would be *much* simpler if code running in user mode sees user addresses. Otherwise we'd end up with very messy and constrained code on single-address-space arches like x86 and we might not be able to implement it at all on split-address-space arches like s390. That being said, writing a bit of PIC code that parses the ELF file, finds some unused address space, and relocates itself out of the way shouldn't be *that* hard. --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
