Re: [PATCH v2 2/3] kallsyms: Add APIs to match symbol without .XXXX suffix.
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2024-08-05 13:45:51
Also in:
live-patching, lkml
On Fri, 2 Aug 2024 14:08:34 -0700 Song Liu [off-list ref] wrote:
With CONFIG_LTO_CLANG=y, the compiler may add suffix to function names to avoid duplication. This causes confusion with users of kallsyms. On one hand, users like livepatch are required to match the symbols exactly. On the other hand, users like kprobe would like to match to original function names. Solve this by splitting kallsyms APIs. Specifically, existing APIs now should match the symbols exactly. Add two APIs that match only the part without .XXXX suffix. Specifically, the following two APIs are added. 1. kallsyms_lookup_name_without_suffix() 2. kallsyms_on_each_match_symbol_without_suffix() These APIs will be used by kprobe. Also cleanup some code and update kallsyms_selftests accordingly. Signed-off-by: Song Liu <song@kernel.org>
Looks good to me, but I have a nitpick.
quoted hunk ↗ jump to hunk
--- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c@@ -164,30 +164,27 @@ static void cleanup_symbol_name(char *s) { char *res; - if (!IS_ENABLED(CONFIG_LTO_CLANG)) - return; - /* * LLVM appends various suffixes for local functions and variables that * must be promoted to global scope as part of LTO. This can break * hooking of static functions with kprobes. '.' is not a valid - * character in an identifier in C. Suffixes only in LLVM LTO observed: - * - foo.llvm.[0-9a-f]+ + * character in an identifier in C, so we can just remove the + * suffix. */ - res = strstr(s, ".llvm."); + res = strstr(s, ".");
nit: "strchr(s, '.')" ? Anyway, Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thank you, -- Masami Hiramatsu (Google) [off-list ref]