On Fri, May 26, 2023 at 07:54:17PM +0100, Greg KH wrote: > On Mon, May 22, 2023 at 10:33:44PM +0200, Jiri Olsa wrote: > > hi, > > we see broken access to user space with bpf_probe_read/bpf_probe_read_str > > helpers on arm64 with 5.4 kernel. The problem is that both helpers try to > > read user memory by calling probe_kernel_read, which seems to work on x86 > > but fails on arm64. > > Has this ever worked on arm64 for the 5.4 kernel tree? If not, it's not > really a regression, and so, why not use a newer kernel that has this > new feature added to it there? > > In other words, what requires you to use the 5.4.y tree and requires > feature parity across architectures? we have a customer running ok on x86 v5.4, but arm64 is broken with the same bpf/user space code upgrade is an option of course, but it's not a big change and we can have 5.4 working on arm64 as well I can send out the change that will be closer to upstream changes, if that's a concern.. with adding the new probe helpers, which I guess is not a problem, because it does not change current API jirka
