Hi Alexei, Naveen, On 11/04/2017 11:01 PM, Naveen N. Rao wrote: > > I think the offsets described in dwarf were incorrect with > CONFIG_GCC_PLUGIN_RANDSTRUCT, but I'll let Sandipan confirm that. >
I think that the offsets described in dwarf are probably incorrect when CONFIG_GCC_PLUGIN_RANDSTRUCT is enabled. To verify this, I used perf to attach a probe to try_to_wake_up() which is the also the function to which waker() is attached in the previously mentioned kernel sample. So, if the run the following: # perf probe "try_to_wake_up" "p->pid" # perf record -a -e probe:try_to_wake_up # perf script The value of p->pid is reported as 0. Similarly, if I try to read p->comm, it is reported to be an empty string. The same problem is seen with systemtap as well. Also, if I do a printk with offsetof(struct task_struct, pid) and offsetof(struct task_struct, comm) inside the kernel code and then compare the values with the offsets reported by pahole, they are completely different. - Sandipan
