Re: Re-send [PATCH] : Validating address in runtime

[Srinivasa DS <srinivasa at in dot ibm dot com>]

Wenji Huang wrote:
> Hi,
>
> Regarding PR6646, seems no good way to solve it. I just think maybe 
> double checking the address in runtime to make things safer.
>
> This patch adds validating address vs name mapping in runtime for 
> several symbols which are used in initializing process.    So kernel 
> oops could be early avoided in case of incorrect vmlinux or wrong address.
>
> Any comments are welcome.
>   ........................................
>   .......................................
> 	  return -1;
> 	}
>
> +	if (_stp_validate_addr("modules_op", (unsigned long)modules_op))
> +	  return -1;
> +

Above mentioned code breaks systemtap on ppc64 systems, Execution of a 
basic systemtap script fails with following error. I removed above 3 
lines of code and now systemtap works well.

[root@llm27lp1 systemtap]# ./stap  -e 'probe kernel.function("sys_open") 
{ printf("hello\n")}'
Error inserting module 
'/tmp/stapIrEgpn/stap_be5242edefcfe2d56878f1a090e33b6b_250.ko': 
Operation not permitted
Pass 5: run failed.  Try again with more '-v' (verbose) options.
=========================
dmesg shows

Systemtap Error at _stp_validate_addr:191 Incorrect mapping 
0xc0000000005da7d0 vs modules_op.
Systemtap Error at _stp_transport_init:277 failed to initialize modules
================


Thanks
 Srinivasa DS.