On 6/20/20 9:22 AM, Matt Pallissard wrote:
New to bpf here.
I'm trying to read values out of of mm_struct. I have code like this;
unsigned long i[10] = {};
struct task_struct *t;
struct mm_rss_stat *rss;
t = (struct task_struct *)bpf_get_current_task();
BPF_CORE_READ_INTO(&rss, t, mm, rss_stat);
BPF_CORE_READ_INTO(i, rss, count);
However, all values in `i` appear to be 0 (i[MM_FILEPAGES], etc), as if no data gets copied. I'm about 100% confident that this is caused by a glaring oversight on my part.
Maybe you want to check the return value of BPF_CORE_READ_INTO.
Underlying it is using bpf_probe_read and bpf_probe_read may fail e.g.,
due to major fault.
Any advice or documentation I could sift through would be greatly appreciated. Thanks.
Matt Pallissard
