scripts/kallysms: always include __start and __stop symbols

These symbols are used to denote section boundaries: by always including
them we can unify loading sections from modules with loading built-in
sections, which leads to some significant cleanup.

Link: https://lkml.kernel.org/r/20240321163705.3067592-5-surenb@google.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/kallsyms.c

@@ -204,13 +204,26 @@ static int symbol_in_range(const struct sym_entry *s,
 	return 0;
 }
 
+static bool string_starts_with(const char *s, const char *prefix)
+{
+	return strncmp(s, prefix, strlen(prefix)) == 0;
+}
+
 static int symbol_valid(const struct sym_entry *s)
 {
 	const char *name = sym_name(s);
 
 	/* if --all-symbols is not specified, then symbols outside the text
 	 * and inittext sections are discarded */
 	if (!all_symbols) {
+		/*
+		 * Symbols starting with __start and __stop are used to denote
+		 * section boundaries, and should always be included:
+		 */
+		if (string_starts_with(name, "__start_") ||
+		    string_starts_with(name, "__stop_"))
+			return 1;
+
 		if (symbol_in_range(s, text_ranges,
 				    ARRAY_SIZE(text_ranges)) == 0)
 			return 0;