[patch 11/38] objtool: Allow STT_NOTYPE -> STT_FUNC+0 tail-calls

Thomas Gleixner
2022-07-16T23:17:56Z

Allow STT_NOTYPE to tail-call into STT_FUNC, per definition STT_NOTYPE
is not a sub-function of the STT_FUNC.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
tools/objtool/check.c | 29 ++++++++++++++++++++---------
1 file changed, 20 insertions(+), 9 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1420,6 +1420,16 @@ static void add_return_call(struct objto

static bool same_function(struct instruction *insn1, struct instruction *insn2)
{
+ if (!insn1->func && !insn2->func)
+ return true;
+
+ /* Allow STT_NOTYPE -> STT_FUNC+0 tail-calls */
+ if (!insn1->func && insn1->func != insn2->func)
+ return false;
+
+ if (!insn2->func)
+ return true;
+
return insn1->func->pfunc == insn2->func->pfunc;
}

@@ -1537,18 +1547,19 @@ static int add_jump_destinations(struct
strstr(jump_dest->func->name, ".cold")) {
insn->func->cfunc = jump_dest->func;
jump_dest->func->pfunc = insn->func;
-
- } else if (!same_function(insn, jump_dest) &&
- is_first_func_insn(file, jump_dest)) {
- /*
- * Internal sibling call without reloc or with
- * STT_SECTION reloc.
- */
- add_call_dest(file, insn, jump_dest->func, true);
- continue;
}
}

+ if (!same_function(insn, jump_dest) &&
+ is_first_func_insn(file, jump_dest)) {
+ /*
+ * Internal sibling call without reloc or with
+ * STT_SECTION reloc.
+ */
+ add_call_dest(file, insn, jump_dest->func, true);
+ continue;
+ }
+
insn->jump_dest = jump_dest;
}