On Tue, 29 Jan 2019 16:53:27 +0100 Heiko Carstens <heiko.carstens@xxxxxxxxxx> wrote: > > > And if I'm correct it is not easy to "fix". _If_ this functionality is > > > desired then the kprobes interface must probably be changed so that it > > > would be possible to specify the address space from where something > > > should be copied. Or.. maybe the "__user" annotation in the kernel > > > code can be instrumented(?). > > > > No, I don't want to "fix" this. Describing in a document will be OK, > > but this is a limitation comes from its design. > > It could be fixed if e.g. a new ustring fetcharg type would be > supported, where we don't switch to KERNEL_DS. It would still fault > when the page isn't mapped, but would access the correct address > space. Ah, I got it, so the user space will be mapped somewhere. > I don't know if it is really worth to implement this.. since I'm > afraid this will cause "some" problems ;) If someone (who can work on s390) is interested in, feel free to expand string copy function, but I don't like introducing "ustring", since it is highly depending on arch and anyway we can not guarantee to fetch the string when the page is not mapped.. Thank you, -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
