On Thu, Dec 21, 2023 at 10:18 AM Daniel Xu <dxu@xxxxxxxxx> wrote: > > Hi Alexei, > > On Thu, Dec 21, 2023 at 10:07:33AM -0800, Alexei Starovoitov wrote: > > On Thu, Dec 21, 2023 at 9:43 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote: > > > > > > On 21/12/2023 17:05, Alexei Starovoitov wrote: > > > > On Thu, Dec 21, 2023 at 12:35 AM Jiri Olsa <olsajiri@xxxxxxxxx> wrote: > > > >> you need to pick up only 'BTF_ID(func, ...)' IDs that belongs to SET8 lists, > > > >> which are bounded by __BTF_ID__set8__<name> symbols, which also provide size > > > > > > > > +1 > > > > > > > >>> > > > >>> Maybe we need a codemod from: > > > >>> > > > >>> BTF_ID(func, ... > > > >>> > > > >>> to: > > > >>> > > > >>> BTF_ID(kfunc, ... > > > >> > > > >> I think it's better to keep just 'func' and not to do anything special for > > > >> kfuncs in resolve_btfids logic to keep it simple > > > >> > > > >> also it's going to be already in pahole so if we want to make a fix in future > > > >> you need to change pahole, resolve_btfids and possibly also kernel > > > > > > > > I still don't understand why you guys want to add it to vmlinux BTF. > > > > The kernel has no use in this additional data. > > > > It already knows about all kfuncs. > > > > This extra memory is a waste of space from kernel pov. > > > > Unless I am missing something. > > > > > > > > imo this logic belongs in bpftool only. > > > > It can dump vmlinux BTF and emit __ksym protos into vmlinux.h > > > > > > > > > > If the goal is to have bpftool detect all kfuncs, would having a BPF > > > kfunc iterator that bpftool could use to iterate over registered kfuncs > > > work perhaps? > > > > The kernel code ? Why ? > > bpftool can do the same thing as this patch. Iterate over set8 in vmlinux elf. > > I think you're right for vmlinux -- bpftool can look at the elf file on > a running system. But I'm not sure it works for modules. > > IIUC, the actual module ELF can go away while the kernel holds onto the > memory (as with initramfs). And even if that wasn't the case, in > containerized environments you may not be able to always see > /lib/modules or similar. Indeed. Access to .ko files may be difficult even for full root without containers. What is vmlinux BTF before/after for our current set of kfuncs ?
