Re: [PATCH v3 perf,bpf 08/11] perf, bpf: save btf information as headers to perf.data

[Song Liu]

> On Feb 17, 2019, at 3:06 PM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> 
> On Fri, Feb 15, 2019 at 01:53:51PM -0800, Song Liu wrote:
> 
> SNIP
> 
>> +static int process_btf(struct feat_fd *ff, void *data __maybe_unused)
>> +{
>> +	struct perf_env *env = &ff->ph->env;
>> +	u32 count, i;
>> +
>> +	if (do_read_u32(ff, &count))
>> +		return -1;
>> +
>> +	down_write(&env->bpf_progs.bpf_info_lock);
>> +
>> +	for (i = 0; i < count; ++i) {
>> +		struct btf_node btf_node;
>> +		struct btf_node *node;
>> +
>> +		if (__do_read(ff, &btf_node, sizeof(struct btf_node)))
>> +			return -1;
>> +
>> +		node = malloc(sizeof(struct btf_node) + btf_node.data_size);
>> +		if (!node)
>> +			return -1;
>> +
>> +		node->id = btf_node.id;
>> +		node->data_size = btf_node.data_size;
>> +
>> +		if (__do_read(ff, node->data, btf_node.data_size)) {
>> +			free(node);
>> +			return -1;
>> +		}
> 
> hows endianity swap handled got struct btf_node and data in here?
> 
> thanks,
> jirka

I thought about endianity at some point, but forgot about it. Let 
me see how to fix it. 

Thanks,
Song