a short script for static function call tracing

a short script for static function call tracing

[Masami Hiramatsu]

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Hi,

Here is a short script for static function call tracing.
Note: currently, this may shows some(or many) false positives.

this is based on cscope, so before using, in kernel tree,

$ make cscope

and

$ ./trace_symbols a_symbol

For example)
$ ./trace_symbols relay_switch_subbuf
(output thousands of functions...)

To avoid tracing unneeded path, you can add IGNORE symbols

For example)
$ IGNORE="__mod_timer" ./trace_symbols relay_switch_subbuf

__mod_timer
BUG
BUG_ON
unlikely
likely
__acquires
__releases
__volatile__
__attribute__
asm
alternative
defined
__asm__
 --- above symbols are ignored  ---
relay_switch_subbuf is calling __mod_timer smp_mb subbuf_start unlikely waitqueue_active
smp_mb is calling barrier mb
barrier is calling __memory_barrier __volatile__
__memory_barrier is calling
mb is calling alternative
subbuf_start is calling
waitqueue_active is calling list_empty
list_empty is calling

Total: 7 symbols are called from relay_switch_subbuf

This means relay_switch_subbuf itself is a very simple function, but __mod_timer
may call many functions...

Thanks,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com


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#!/bin/sh
[ $# -ne 1 ] && echo "usage: trace_symbol <symbol> " && exit 0
# NOTE: currently sometimes cscope returns fales positive function calls
# like indirect call handler name, or the functions in other scopes.

TMP=`mktemp callers.XXXX`

IGNORE="$IGNORE BUG BUG_ON unlikely likely __acquires __releases __volatile__ __attribute__ asm alternative defined __asm__"
for i in $IGNORE; do 
  echo "$i " >> $TMP
done
echo " --- above symbols are ignored  --- " >> $TMP

COUNT=-1 # reduce 1 for the original symbol

function _getcaller() {
  cscope -dq -2$1 -L| cut -d\  -f2 | sort | uniq | xargs
}

function getcaller() {
  local _CALLER=`_getcaller $1`
  local i=
  echo $1 is calling $_CALLER >> $TMP
  echo -ne "$COUNT : $1 \t\t\t\r"
  COUNT=$((COUNT+1))
  for i in $_CALLER; do
    `grep "^$i " $TMP > /dev/null` && continue
    getcaller $i
  done
}

getcaller $1
echo -- finished
echo  
cat $TMP
echo 
echo "Total: $COUNT symbols are called from $1"

rm $TMP