tracing/probes: Treating longer symbol name on event comparation

MAX_COMMON_HEAD_LEN (63) was used to allocate a temporary buffer for
formatting command heads in trace_kprobe_match_command_head() and
trace_uprobe_match_command_head(). However, the buffer size is too
short for some longer symbols. Especially, with rust code, the symbol
can be mangled and become very long.

Refactor trace_kprobe_match_command_head() to perform direct string
comparisons using strcmp() and strncmp(), eliminating the need for a
temporary buffer and removing the MAX_COMMON_HEAD_LEN string length
restriction on probe symbol names.

For trace_uprobe_match_command_head(), since tu->filename is already
matched via strncmp(), use a fixed 64-byte stack buffer solely for
formatting offset and ref_ctr_offset (which requires at most 39 bytes).

With all users converted, remove the MAX_COMMON_HEAD_LEN definition from
trace_probe.h.

Link: https://lore.kernel.org/all/178521361102.34226.9650586522488974115.stgit@devnote2/

Reported-by: Zhan Xusheng <zhanxusheng1024@gmail.com>
Link: https://lore.kernel.org/all/20260724023317.624074-1-zhanxusheng@xiaomi.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

0 files changed, 0 insertions, 0 deletions