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Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings

From Arnd Bergmann <arnd@arndb.de>
Newsgroups linux.kernel
Subject Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings
Date 2017-03-03 10:30 +0100
Message-ID <tgRHb-7yR-5@gated-at.bofh.it> (permalink)
References (6 earlier) <tggeC-6gA-7@gated-at.bofh.it> <tgleh-1ix-9@gated-at.bofh.it> <tgnzr-34a-7@gated-at.bofh.it> <tgIaR-Qo-9@gated-at.bofh.it> <tgINA-13L-19@gated-at.bofh.it>
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On Fri, Mar 3, 2017 at 12:05 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> I assume '-Wdiv-by-zero' is enabled and gcc isn't showing the "division
> by zero" warning for either of these?  The 'ud2' is guaranteed to
> trigger since the function has no branches.  Surely at least the missing
> warning is a gcc bug.
>
> The good news is objtool is flushing these out, albeit with a confusing
> message.

I'm still not sure if it's intentional or not. I've reduced the test case to the
simple

static inline int return0(void) { return 0; }
int provoke_div0_warning(void) { return 1 / return0(); }

which does not generate a compile-time warning, but will generate
an unconditional runtime warning if built with -fsanitze=integer-divide-by-zero.

     Arnd

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Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-01 10:40 +0100
  Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-01 11:00 +0100
    Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-01 15:50 +0100
      Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-01 18:30 +0100
        Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-01 23:10 +0100
        Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-01 23:50 +0100
          Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-02 02:20 +0100
            Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Ingo Molnar <mingo@kernel.org> - 2017-03-02 07:40 +0100
              Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Ingo Molnar <mingo@kernel.org> - 2017-03-02 15:00 +0100
                Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-02 15:30 +0100
                Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Ingo Molnar <mingo@kernel.org> - 2017-03-02 15:50 +0100
              Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-02 15:10 +0100
            Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-03 00:20 +0100
              Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-03 01:00 +0100
                Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-03 10:30 +0100
                Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-03 16:40 +0100
  Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-01 16:30 +0100
    Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-02 19:40 +0100
      Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2017-03-03 00:00 +0100
        Re: [PATCH] objtool: fix another gcc jump table detection issue Arnd Bergmann <arnd@arndb.de> - 2017-03-03 00:10 +0100
        [PATCH] objtool: fix another gcc jump table detection issue Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-03 04:20 +0100
  Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-01 16:30 +0100

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