On Fri, Apr 19, 2024 at 4:57 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > On Tue, 16 Apr 2024 at 16:40, <patchwork-bot+netdevbpf@xxxxxxxxxx> wrote: > > > > Hello: > > > > This series was applied to bpf/bpf-next.git (master) > > by Daniel Borkmann <daniel@xxxxxxxxxxxxx>: > > > > On Mon, 15 Apr 2024 18:20:42 +0200 you wrote: > > > From: Ard Biesheuvel <ardb@xxxxxxxxxx> > > > > > > Weak external linkage is intended for cases where a symbol reference > > > can remain unsatisfied in the final link. Taking the address of such a > > > symbol should yield NULL if the reference was not satisfied. > > > > > > Given that ordinary RIP or PC relative references cannot produce NULL, > > > some kind of indirection is always needed in such cases, and in position > > > independent code, this results in a GOT entry. In ordinary code, it is > > > arch specific but amounts to the same thing. > > > > > > [...] > > > > Here is the summary with links: > > - [v4,1/3] kallsyms: Avoid weak references for kallsyms symbols > > (no matching commit) > > - [v4,2/3] vmlinux: Avoid weak reference to notes section > > (no matching commit) > > - [v4,3/3] btf: Avoid weak external references > > https://git.kernel.org/bpf/bpf-next/c/fc5eb4a84e4c > > > > > Thanks. > > Masahiro, could you pick up patches #1 and #2 please? > I do not like PROVIDE() because it potentially shifts a build error (i.e. link error) into a run-time error, which is usually more difficult to debug than build error. If someone references the kallsyms_* symbols when CONFIG_KALLSYMS=n, it is likely a mistake. In general, it should be reported as a link error. With PROVIDE() added, we will never detect it at a build time. Do you want me to pick up 1/3? -- Best Regards Masahiro Yamada
