Re: [RFC PATCH v4 09/29] bpf tools: Collect version and license from ELF sections

[Wangnan (F)]

On 2015/5/28 9:48, Alexei Starovoitov wrote:
> On Wed, May 27, 2015 at 05:19:44AM +0000, Wang Nan wrote:
> > Expand bpf_obj_elf_collect() to collect license and kernel version
> > information in eBPF object file. eBPF object file should have a section
> > named 'license', which contains a string. It should also have a section
> > named 'version', contains a u32 LINUX_VERSION_CODE.
> >
> > bpf_obj_validate() is introduced to validate object file after loaded.
> > Currently it only check existance of 'version' section.
> >
> > Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> > ---
> ...
> > +static int
> > +bpf_object__init_kversion(struct bpf_object *obj,
> > +			  void *data, size_t size)
> > +{
> > +	u32 kver;
> > +	if (size < sizeof(kver)) {
> shouldn't it be '!=' ?

Is it possible that LLVM pads 'version' section so the size of it becomes
longer than sizeof(u32)?

Thank you.

> > +		pr_warning("invalid kver section in %s\n", obj->path);
> > +		return -EINVAL;
> > +	}
> > +	memcpy(&kver, data, sizeof(kver));
> > +	obj->kern_version = kver;
> > +	pr_debug("kernel version of %s is %x\n", obj->path,
> > +		 obj->kern_version);
> > +	return 0;
> > +}
> > +


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