Re: [PATCH 2/2] powerpc/xmon: use KSYM_NAME_LEN in array size

From: Benjamin Gray
Date: Thu Aug 03 2023 - 01:47:05 EST

On 30/5/23 10:54 pm, Miguel Ojeda wrote:
Side-note: in `get_function_bounds()`, I see `kallsyms_lookup()` being
used, but the name seems discarded? Can
`kallsyms_lookup_size_offset()` be used instead, thus avoiding the
usage of the buffer there to begin with?

I'm not familiar with the kallsyms infrastructure, but looking over the implementations of kallsyms_lookup() and kallsyms_lookup_size_offset() it looks like the existing kallsyms_lookup()
handles an extra case over kallsyms_lookup_size_offset()?

kallsyms_lookup_buildid() (the implementation of kallsyms_lookup()) has

/* See if it's in a module or a BPF JITed image. */
ret = module_address_lookup(addr, symbolsize, offset,
modname, modbuildid, namebuf);
if (!ret)
ret = bpf_address_lookup(addr, symbolsize,
offset, modname, namebuf);

if (!ret)
ret = ftrace_mod_address_lookup(addr, symbolsize,
offset, modname, namebuf);

while kallsyms_lookup_size_offset() is missing the ftrace case

return !!module_address_lookup(addr, symbolsize, offset,
NULL, NULL, namebuf) ||
!!__bpf_address_lookup(addr, symbolsize, offset, namebuf);

Might this be a concern for xmon?