For a procedure, there might be lots of SQL calls etc within it, so you would need to find the session level stats before the call, and compare to after, for example:
SQL> select
2 s.name, st.value
3 from v$statname s, v$mystat st
4 where st.STATISTIC# = s.STATISTIC#
5 and s.name in ('session logical reads','physical reads');
NAME VALUE
-------------------------------------------------- ----------
session logical reads 26152
physical reads 29
SQL> exec my_proc
SQL> select
2 s.name, st.value
3 from v$statname s, v$mystat st
4 where st.STATISTIC# = s.STATISTIC#
5 and s.name in ('session logical reads','physical reads');
NAME VALUE
-------------------------------------------------- ----------
session logical reads 29123
physical reads 689
Note - there's lots of *different* ways of doing a logical and/or physical read nowadays, you might need more than just those two stats, for example
SQL> @statname physical
STATISTIC# NAME
---------- ----------------------------------------------------------------
50 physical read total IO requests
51 physical read total multi block requests
52 physical read requests optimized
53 physical read total bytes optimized
54 physical read partial requests
55 physical read total bytes
56 physical write requests optimized
57 physical write total bytes optimized
61 physical write total IO requests
62 physical write total multi block requests
63 physical write total bytes
64 cell physical IO interconnect bytes
106 physical read snap IO requests base
107 physical read snap IO requests copy
108 physical read snap IO requests no data
109 physical read snap bytes base
110 physical read snap bytes copy
111 physical write snap IO requests new allocations
141 physical reads
142 physical reads cache
143 physical read flash cache hits
144 physical reads direct
145 physical read IO requests
146 physical read bytes
152 physical writes
153 physical writes direct
154 physical writes from cache
155 physical write IO requests
157 physical reads direct temporary tablespace
158 physical writes direct temporary tablespace
159 physical write bytes
171 physical writes non checkpoint
217 physical reads cache prefetch
218 physical reads prefetch warmup
222 physical reads retry corrupt
223 physical reads direct (lob)
224 physical writes direct (lob)
228 physical reads for flashback new
233 physical reads cache for securefile flashback block new
234 physical reads direct for securefile flashback block new
430 cell physical IO bytes saved during optimized file creation
431 cell physical IO bytes saved during optimized RMAN file restore
432 cell physical IO bytes eligible for predicate offload
433 cell physical IO bytes saved by storage index
434 cell physical IO bytes sent directly to DB node to balance CPU
449 cell physical IO interconnect bytes returned by smart scan
459 cell physical IO bytes saved by columnar cache
460 cell physical write bytes saved by smart file initialization
716 cell simulated physical IO bytes eligible for predicate offload
717 cell simulated physical IO bytes returned by predicate offload
1150 cell physical write IO bytes eligible for offload
1151 cell physical write IO host network bytes written during offloa