From 07cc2c931e8e1083a31f4c51d2244fe264af63bf Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Mon, 16 Jan 2023 11:10:07 +0100 Subject: livepatch: Improve the search performance of module_kallsyms_on_each_symbol() Currently we traverse all symbols of all modules to find the specified function for the specified module. But in reality, we just need to find the given module and then traverse all the symbols in it. Let's add a new parameter 'const char *modname' to function module_kallsyms_on_each_symbol(), then we can compare the module names directly in this function and call hook 'fn' after matching. If 'modname' is NULL, the symbols of all modules are still traversed for compatibility with other usage cases. Phase1: mod1-->mod2..(subsequent modules do not need to be compared) | Phase2: -->f1-->f2-->f3 Assuming that there are m modules, each module has n symbols on average, then the time complexity is reduced from O(m * n) to O(m) + O(n). Reviewed-by: Petr Mladek Acked-by: Song Liu Signed-off-by: Zhen Lei Signed-off-by: Jiri Olsa Acked-by: Miroslav Benes Reviewed-by: Luis Chamberlain Link: https://lore.kernel.org/r/20230116101009.23694-2-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/trace/bpf_trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/bpf_trace.c') diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 23ce498bca97..095f7f8d34a1 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2735,7 +2735,7 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3 int err; /* We return either err < 0 in case of error, ... */ - err = module_kallsyms_on_each_symbol(module_callback, &args); + err = module_kallsyms_on_each_symbol(NULL, module_callback, &args); if (err) { kprobe_multi_put_modules(args.mods, args.mods_cnt); kfree(args.mods); -- cgit v1.2.3