linux-kernel - Re: linux-next: Tree for May 2 (objtool bug!)

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Date:   Wed, 2 May 2018 16:06:25 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: linux-next: Tree for May 2 (objtool bug!)

On Wed, May 02, 2018 at 08:59:38AM -0700, Randy Dunlap wrote:
> On 05/02/2018 08:43 AM, Josh Poimboeuf wrote:
> > On Wed, May 02, 2018 at 08:37:53AM -0700, Randy Dunlap wrote:
> >> On 05/01/2018 11:59 PM, Stephen Rothwell wrote:
> >>> Hi all,
> >>>
> >>> Changes since 20180501:
> >>>
> >>
> >> on x86_64 randconfig:
> >>
> >>   CC      fs/cifs/smbencrypt.o
> >> 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!)
> > 
> > Can you share the object file (or at least the .config and GCC version)?
> > 
> 
> gcc (SUSE Linux) 4.8.5
> 
> config and .o file are attached.

Thanks, can you verify this fixes it?

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 92b6a2c21631..dae568fef2c1 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,