Messages in this thread | | | Date | Wed, 4 Nov 2020 02:38:26 +0200 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH v3 1/7] compiler-clang: add build check for clang 10.0.1 |
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On Tue, Nov 03, 2020 at 10:48:27AM -0800, Nick Desaulniers wrote: > On Mon, Nov 2, 2020 at 8:55 PM Jarkko Sakkinen <jarkko@kernel.org> wrote: > > > > On Wed, Sep 02, 2020 at 03:59:05PM -0700, Nick Desaulniers wrote: > > > +#define CLANG_VERSION (__clang_major__ * 10000 \ > > > + + __clang_minor__ * 100 \ > > > + + __clang_patchlevel__) > > > + > > > +#if CLANG_VERSION < 100001 > > > +# error Sorry, your version of Clang is too old - please use 10.0.1 or newer. > > > +#endif > > > > > > I'm trying to compile a BPF enabled test kernel for a live system and I > > get this error even though I have much newer clang: > > > > ➜ ~ (master) ✔ clang --version > > Ubuntu clang version 11.0.0-2 > > Target: x86_64-pc-linux-gnu > > Thread model: posix > > InstalledDir: /usr/bin > > > > Tried to Google for troubleshooter tips but this patch is basically the > > only hit I get :-) > > To check the values of the above preprocessor defines, please run: > $ clang -dM -E - < /dev/null | grep -e __clang_m -e __clang_p > > If you have multiple versions of clang installed, you might not be > running the version you think you are. Particularly, if you're using > bcc, idk if it includes a copy of clang? If that's the case, we may > have to work out how we can support older versions of clang for the > express purposes of bpf.
➜ ~ (master) ✔ clang -dM -E - < /dev/null | grep -e __clang_m -e __clang_p #define __clang_major__ 11 #define __clang_minor__ 0 #define __clang_patchlevel__ 0
I'm compiling the kernel itself with GCC.
Here's an example BPF script that fails on me:
struct sgx_enclave_add_pages { unsigned long src; unsigned long offset; unsigned long length; unsigned long secinfo; unsigned long flags; unsigned long count; };
kprobe:sgx_ioctl { if (arg1 == 0xc030a401) { printf("sgx_ioctl: %d, %lu\n", pid, ((struct sgx_enclave_add_pages *)(arg2))->offset); }
} Note that it relies on code not yet in the mainline.
If I don't declare structs, things work just fine. E.g. the following works:
kprobe:sgx_encl_get_backing { printf("%s\n", func) }
BTW, I don't really understand how scripts/clang-version.sh is even supposed to work, if you compile the kernel itself with GCC. In that case there would be no output, right? And thus version gets set to zero...
> -- > Thanks, > ~Nick Desaulniers
/Jarkko
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