Re: libbpf: Loading kprobes fail on some distros

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‫בתאריך יום ב׳, 12 באוק׳ 2020 ב-20:02 מאת ‪Andrii Nakryiko‬‏
<‪andrii.nakryiko@xxxxxxxxx‬‏>:‬
>
> On Sun, Oct 11, 2020 at 7:10 PM Yaniv Agman <yanivagman@xxxxxxxxx> wrote:
> >
> > Trying to load kprobes on ubuntu 4.15.0, I get the following error:
> > libbpf: load bpf program failed: Invalid argument
> >
> > The same kprobes load successfully using bcc
> >
> > After some digging, I found that the issue was with the kernel version
> > given to the bpf syscall. While libbpf calculated the value 265984 for
> > the kern_version argument, bcc used 266002.
> > It turns out that some distros (e.g. ubuntu, debian) change the patch
> > number of the kernel version, as detailed in:
> > https://github.com/ajor/bpftrace/issues/8
> >
> > I didn't find a proper API in libbpf to load kprobes in such cases -
> > is there any?
>
> Yes, you can override kernel version that libbpf determines from
> utsname with a special variable in your BPF code:
>
> int KERNEL_VERSION SEC("version") = 123;

Thanks! This is trivial, I should have thought about it myself.
For some reason, I thought that the loader should handle that, but if I include
int KERNEL_VERSION SEC("version") = LINUX_VERSION_CODE;
It should just work

Thanks again!




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