Re: [PATCH v4 15/22] objtool: Prevent kCFI hashes from being decoded as instructions

On Tue, Aug 11, 2026 at 5:30 PM Josh Poimboeuf [off-list ref] wrote:

On Tue, Aug 11, 2026 at 04:58:05PM -0700, Song Liu wrote:

quoted

On Sat, Aug 8, 2026 at 4:18 PM Josh Poimboeuf [off-list ref] wrote:
[...]

quoted

+/*
+ * ARM64 mapping symbols ($d, $x, $a, __pi_$d, etc) which mark transitions
+ * between code and data.
+ */
+static inline bool is_mapping_sym(struct symbol *sym)
+{
+       return is_notype_sym(sym) && strchr(sym->name, '$');
+}
+
+static inline bool is_data_mapping_sym(struct symbol *sym)
+{
+       const char *dollar;
+
+       if (!is_mapping_sym(sym))
+               return false;
+
+       dollar = strchr(sym->name, '$');
+       return dollar && dollar[1] == 'd';

nit: is_data_mapping_sym() calls strchr() twice. Maybe we can
optimize it by eliminating a strchr()?

I suppose it's a bit funky, but the compiler CSEs it, so it's harmless.

I see. Then this should be fine.

Thanks!

Acked-by: Song Liu <song@kernel.org>