error: Compiler does not support fentry

[karim-manaouil]

Hi,

I tried to include <linux/perf_event.h> to have access to struct pmu in the following program

#include <linux/perf_event.h>

k:perf_pmu_enable {
        $s = ksym(((struct pmu *)arg0)->pmu_enable);
        printf("%s\n", $s);
}

and got the following error coming from ftrace.h.

/lib/modules/6.7.6+/build/arch/x86/include/asm/processor.h:519:17: warning: taking address of packed member 'sp0' of class or structure 'x86_hw_tss' may result in an unaligned pointer value [-Waddress-of-packed-member]
/lib/modules/6.7.6+/build/arch/x86/include/asm/ftrace.h:7:3: error: Compiler does not support fentry?
/lib/modules/6.7.6+/build/include/linux/cgroup-defs.h:556:16: warning: field 'cgrp' with variable sized type 'struct cgroup' not at the end of a struct or class is a GNU extension [-Wgnu-variable-sized-type-not-at-end]

Probably because clang doesn't support fentry. Is there anything I can do about it?

Edit: added bpftrace program

[danobi]

Hi, can you please share the script you tried to run?

[karim-manaouil]

@danobi I edited the post and added the script

[danobi]

Thanks!

[danobi]

The script fails for me as well. But if I remove the #include, it works. Can you try that?

See https://github.com/bpftrace/bpftrace/blob/master/man/adoc/bpftrace.adoc#btf-support for more details about why removing the #include helps

[karim-manaouil]

Works! Awesome! Thanks for pointing out the BTF stuff! Yaay!! No more #includes!