Description of problem:
cmdline_arg output need to be fixed.

Version-Release number of selected component (if applicable):
systemtap-2.2.1-1.fc18.i686

How reproducible:
Always

Steps to Reproduce:
1.Run following stap script.

probe kprobe.function("sys_unlinkat")
{
  asmlinkage()
  printf("cmdline_arg(0)= %s\n", cmdline_arg(0))
  printf("cmdline_arg(1)= %s\n", cmdline_arg(1))
  printf("cmdline_arg(2)= %s\n", cmdline_arg(2))
  printf("cmdline_str= %s\n", cmdline_str())
}

2. Remove a file

Actual results:

cmdline_arg(0)= rm""fabc123
cmdline_arg(1)= -f""bc123
cmdline_arg(2)= abc123
cmdline_str= rm -f abc123

Expected results:

cmdline_arg(0)= rm -f abc123
cmdline_arg(1)= -f
cmdline_arg(2)= abc123
cmdline_str= rm -f abc123

Additional info:
Also the latest version 2.4/0.155, commit release-2.3-70-g1ab99b2
have the same issue.

I put an output of cmdline_str as a good example.
cmdline_arg(0) and cmdline_str should be the same result.