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    Subject[PATCH v4 16/21] objtool: Disable CFI warnings
    From
    The __cfi_ preambles contain a mov instruction that embeds the KCFI
    type identifier in the following format:

    ; type preamble
    __cfi_function:
    mov <id>, %eax
    function:
    ...

    While the preamble symbols are STT_FUNC and contain valid
    instructions, they are never executed and always fall through. Skip
    the warning for them.

    .kcfi_traps sections point to CFI traps in text sections. Also skip
    the warning about them referencing !ENDBR instructions.

    Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
    Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
    ---
    tools/objtool/check.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    diff --git a/tools/objtool/check.c b/tools/objtool/check.c
    index e55fdf952a3a..48e18737a2d1 100644
    --- a/tools/objtool/check.c
    +++ b/tools/objtool/check.c
    @@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
    next_insn = next_insn_to_validate(file, insn);

    if (func && insn->func && func != insn->func->pfunc) {
    + /* Ignore KCFI type preambles, which always fall through */
    + if (!strncmp(func->name, "__cfi_", 6))
    + return 0;
    +
    WARN("%s() falls through to next function %s()",
    func->name, insn->func->name);
    return 1;
    @@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file)
    !strcmp(sec->name, "__bug_table") ||
    !strcmp(sec->name, "__ex_table") ||
    !strcmp(sec->name, "__jump_table") ||
    - !strcmp(sec->name, "__mcount_loc"))
    + !strcmp(sec->name, "__mcount_loc") ||
    + !strcmp(sec->name, ".kcfi_traps"))
    continue;

    list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
    --
    2.37.2.672.g94769d06f0-goog
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