From: tixy@linaro.org (Jon Medhurst (Tixy))
To: linux-arm-kernel@lists.infradead.org
Subject: Kprobes build failure
Date: Fri, 26 Sep 2014 10:57:23 +0100 [thread overview]
Message-ID: <1411725443.1529.10.camel@linaro1.home> (raw)
In-Reply-To: <20140925233720.GG5182@n2100.arm.linux.org.uk>
On Fri, 2014-09-26 at 00:37 +0100, Russell King - ARM Linux wrote:
> So, Olof's kbuild found this while building my rc5 based for-next tree:
>
> arm.allmodconfig:
> /tmp/ccoT403o.s:21439: Error: bad immediate value for offset (4168)
> /tmp/ccoT403o.s:21440: Error: bad immediate value for offset (4176)
> /tmp/ccoT403o.s:21475: Error: bad immediate value for offset (4260)
> /tmp/ccoT403o.s:21476: Error: bad immediate value for offset (4260)
> /tmp/ccoT403o.s:23566: Error: bad immediate value for offset (4132)
> /tmp/ccoT403o.s:23567: Error: bad immediate value for offset (4148)
> /tmp/ccoT403o.s:23606: Error: bad immediate value for offset (4236)
> /tmp/ccoT403o.s:23607: Error: bad immediate value for offset (4248)
>
> which, when looking at the logs, appears to be:
>
> /tmp/ccoT403o.s:47583: Error: bad immediate value for offset (5464)
> make[3]: *** [arch/arm/kernel/kprobes-test-arm.o] Error 1
> make[3]: Target `__build' not remade because of errors.
> make[2]: *** [arch/arm/kernel] Error 2
>
> Any ideas?
Sounds vaguely familiar as a problem I hit before. Google finds someone
else hitting similar problem [1] and the symptoms and cause match my
memories of the old kprobe issue.
Where can I find a clue of to the config and compiler used in Olof's
build, so I can have a go at reproducing and debugging?
[1] https://lkml.org/lkml/2012/9/24/223
The relevant explanation of the above post copied below...
------------------------------------------------------------------------
The compiler uses a pretty dumb heuristic to guess the size of asms:
4 * (number of ; or \n in the string)
Directives that the compiler can't predict the size of are not safe if
they output into any segment that the compiler uses. .fill/.skip are
obvious candidates, but macro expansions, .rept, .irp etc. can cause
these problems too.
For example:
void g(int);
void f(void)
{
g(0xd00dfeed);
asm(".skip 0x1000");
}
If you try building this with gcc -marm -Os for example:
/tmp/ccXYm1uP.s: Assembler messages:
/tmp/ccXYm1uP.s:21: Error: bad immediate value for offset (4100)
...because the assembler assumes that it can dump a literal at the end
of the function and reference it from the g() callsite.
------------------------------------------------------------------------
--
Tixy
next prev parent reply other threads:[~2014-09-26 9:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-25 23:37 Kprobes build failure Russell King - ARM Linux
2014-09-26 9:57 ` Jon Medhurst (Tixy) [this message]
2014-09-26 11:53 ` Jon Medhurst (Tixy)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1411725443.1529.10.camel@linaro1.home \
--to=tixy@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).