From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Denys Vlasenko <dvlasenk@redhat.com>
Subject: Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings
Date: Wed, 1 Mar 2017 10:53:55 -0600 [thread overview]
Message-ID: <20170301165355.w2kmdmbql2f2ouzg@treble> (raw)
In-Reply-To: <CAK8P3a0BUDCUE7qT=tAh4U2LNOqHUBDadRJXsbJMT3cX3hnVnQ@mail.gmail.com>
On Wed, Mar 01, 2017 at 04:27:29PM +0100, Arnd Bergmann wrote:
> On Wed, Mar 1, 2017 at 3:40 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Wed, Mar 01, 2017 at 10:45:03AM +0100, Arnd Bergmann wrote:
>
> >> Actually, something must have changed in gcc since last month, I also
> >> just got a report in another file:
> >>
> >> drivers/i2c/busses/i2c-img-scb.o: warning: objtool: img_i2c_probe()
> >> falls through to next function img_i2c_read_fifo()
> >
> > This one looks like it could be related to some recent objtool changes
> > which affect how it interprets 'ud2'. Which commit were you testing
> > with? Can you provide the .config file, and the object file if it's not
> > too big?
>
> This is with my randconfig test series on top of latest linux-next.
> I see it with the latest gcc-7.0.1 snapshot as well as an earlier gcc-7.0.0
> build (20161201), but not with gcc-6.3.1
I wonder if this is another gcc bug. gcc inserted two ud2 instructions
in img_i2c_probe() for no apparent reason. Here's one of them:
5c3: e8 00 00 00 00 callq 5c8 <img_i2c_probe+0x298>
5c4: R_X86_64_PC32 dev_warn-0x4
5c8: 8b 05 00 00 00 00 mov 0x0(%rip),%eax # 5ce <img_i2c_probe+0x29e>
5ca: R_X86_64_PC32 .data+0xec
5ce: 89 83 70 06 00 00 mov %eax,0x670(%rbx)
5d4: 0f 0b ud2
Which corresponds to the following code block:
if (i2c->bitrate > timings[ARRAY_SIZE(timings) - 1].max_bitrate) {
dev_warn(i2c->adap.dev.parent,
"requested bitrate (%u) is higher than the max bitrate supported (%u)\n",
i2c->bitrate,
timings[ARRAY_SIZE(timings) - 1].max_bitrate);
timing = timings[ARRAY_SIZE(timings) - 1];
i2c->bitrate = timing.max_bitrate;
}
I see no apparent reason for the ud2.
Can you rebuild the object with CONFIG_DEBUG_INFO and use addr2line to
see what code lines are associated with the ud2's?
--
Josh
next prev parent reply other threads:[~2017-03-01 17:21 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-10 12:56 [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann
2016-10-10 20:23 ` Josh Poimboeuf
2016-10-11 8:08 ` Arnd Bergmann
2016-10-11 12:20 ` Josh Poimboeuf
2016-10-11 13:30 ` Arnd Bergmann
2016-10-11 15:05 ` Josh Poimboeuf
2016-10-11 15:51 ` Josh Poimboeuf
2016-10-11 20:38 ` Arnd Bergmann
2016-10-12 13:01 ` Josh Poimboeuf
2016-10-13 12:46 ` Another gcc corruption bug (was Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings) Josh Poimboeuf
2016-10-13 17:57 ` Denys Vlasenko
2016-10-13 20:15 ` Josh Poimboeuf
2017-03-01 9:34 ` [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann
2017-03-01 9:45 ` Arnd Bergmann
2017-03-01 14:40 ` Josh Poimboeuf
2017-03-01 15:27 ` Arnd Bergmann
2017-03-01 16:53 ` Josh Poimboeuf [this message]
2017-03-01 22:05 ` Arnd Bergmann
2017-03-01 22:42 ` Arnd Bergmann
2017-03-02 1:03 ` Josh Poimboeuf
2017-03-02 6:31 ` Ingo Molnar
2017-03-02 12:49 ` Josh Poimboeuf
2017-03-02 13:46 ` Ingo Molnar
2017-03-02 14:08 ` Josh Poimboeuf
2017-03-02 14:46 ` Ingo Molnar
2017-03-02 22:49 ` Arnd Bergmann
2017-03-02 23:05 ` Josh Poimboeuf
2017-03-03 8:58 ` Arnd Bergmann
2017-03-03 11:27 ` Arnd Bergmann
2017-03-01 14:31 ` Josh Poimboeuf
2017-03-01 15:21 ` Arnd Bergmann
2017-03-02 18:25 ` Josh Poimboeuf
2017-03-02 22:43 ` Arnd Bergmann
2017-03-02 22:57 ` [PATCH] objtool: fix another gcc jump table detection issue Josh Poimboeuf
2017-03-02 23:01 ` Arnd Bergmann
2016-10-11 1:53 ` [PATCH] objtool: support '-mtune=atom' stack frame setup instruction Josh Poimboeuf
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