On Wed, 13 May 2020 16:59:40 -0700 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Wed, May 13, 2020 at 4:21 PM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > > > > > For trace_kprobe.c current order (kernel -> user fallback) is preferred > > because it has another function dedicated for user memory. > > Well, then it should just use the "strict" kernel-only one for the > non-user memory. > > But yes, if there are legacy interfaces, then we might want to say > "these continue to work for the legacy case on platforms where we can > tell which kind of pointer it is from the bit pattern". Yes, that was why I changed my mind and send reviewed-by last time. https://lore.kernel.org/bpf/20200511142716.f1ff6fc55220012982c47fec@xxxxxxxxxx/ > But we should likely at least disallow it entirely on platforms where > we really can't - or pick one hardcoded choice. On sparc, you really > _have_ to specify one or the other. OK. BTW, is there any way to detect the kernel/user space overlap on memory layout statically? If there, I can do it. (I don't like "if (CONFIG_X86)" thing....) Or, maybe we need CONFIG_ARCH_OVERLAP_ADDRESS_SPACE? Thank you, -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
