Commit-ID: 0afd0d9e0e7879d666c1df2fa1bea4d8716909fe Gitweb: https://git.kernel.org/tip/0afd0d9e0e7879d666c1df2fa1bea4d8716909fe Author: Josh Poimboeuf <[email protected]> AuthorDate: Wed, 9 May 2018 22:39:14 -0500 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 14 May 2018 10:20:53 +0200
objtool: Fix "noreturn" detection for recursive sibling calls Objtool has some crude logic for detecting static "noreturn" functions (aka "dead ends"). This is necessary for being able to correctly follow GCC code flow when such functions are called. It's remotely possible for two functions to call each other via sibling calls. If they don't have RET instructions, objtool's noreturn detection logic goes into a recursive loop: drivers/char/ipmi/ipmi_ssif.o: warning: objtool: return_hosed_msg()+0x0: infinite recursion (objtool bug!) drivers/char/ipmi/ipmi_ssif.o: warning: objtool: deliver_recv_msg()+0x0: infinite recursion (objtool bug!) Instead of reporting an error in this case, consider the functions to be non-dead-ends. Reported-and-tested-by: Randy Dunlap <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: David Laight <[email protected]> Cc: Greg KH <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: damian <[email protected]> Link: http://lkml.kernel.org/r/7cc156408c5781a1f62085d352ced1fe39fe2f91.1525923412.git.jpoim...@redhat.com Signed-off-by: Ingo Molnar <[email protected]> --- tools/objtool/check.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 5409f6f6c48d..264522d4e4af 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -190,9 +190,13 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func, continue; if (recursion == 5) { - WARN_FUNC("infinite recursion (objtool bug!)", - dest->sec, dest->offset); - return -1; + /* + * Infinite recursion: two functions + * have sibling calls to each other. + * This is a very rare case. It means + * they aren't dead ends. + */ + return 0; } return __dead_end_function(file, dest_func,
