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    Subject[PATCH v3 32/59] objtool: Allow STT_NOTYPE -> STT_FUNC+0 tail-calls
    From: Peter Zijlstra <peterz@infradead.org>

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

    --- a/tools/objtool/check.c
    +++ b/tools/objtool/check.c
    @@ -1370,6 +1370,16 @@ 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;
    }

    @@ -1487,18 +1497,19 @@ 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;
    }


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