<div dir="ltr">--rosegment puts read-only data and executable text in a single segment and make it executable, so your read-only code becomes executable. I think that shouldn't be a default behavior. If valgrind needs that, we can't fix it by changing the default.<br><br><div class="gmail_quote"><div dir="ltr">On Thu, Apr 5, 2018 at 2:50 PM Andrew Kelley via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Confirmed that -no-rosegment worked around the issue.<br><br></div>However, a valgrind developer says that perhaps LLD is generating strange object files:<br><br><tomhughes> I suspect that is some extra ro segment in addition to the normal rodata<br><tomhughes> so without it you have two<br><tomhughes> but I know nothing about lld<br><tomhughes> but without an executable to examine/test it's hard to be sure<br><andrewrk> the not working elf file has only 1 .rodata section<br><andrewrk> here's the difference between bad and good headers: <a href="https://clbin.com/vvB8O" target="_blank">https://clbin.com/vvB8O</a><br><tomhughes> ah I see it's because it's a mapped ro segment in the phdrs<br><tomhughes> don't think it's the problem but this file is quite odd - the ro segment in the phdrs doesn't seem to have to any section listed in the shdrs<br><tomhughes> s/have/map/<br><div><div><div class="gmail_extra"><br></div><div class="gmail_extra">Is this something where LLD can be reasonably changed to be compatible with valgrind without this workaround?<br><br></div><div class="gmail_extra">Thanks,<br></div><div class="gmail_extra">Andrew<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Apr 5, 2018 at 5:28 PM, Andrew Kelley <span dir="ltr"><<a href="mailto:superjoe30@gmail.com" target="_blank">superjoe30@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>As a frontend, what are the downsides of enabling --no-rosegment by default?<br><br></div><div>So far the pro list is:<br></div><div> * valgrind debug info will work by default<br><br></div><div>What's on the con list?<br></div><div><div class="m_-2122909633160941005gmail-h5"><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Apr 5, 2018 at 5:16 PM, Shoaib Meenai <span dir="ltr"><<a href="mailto:smeenai@fb.com" target="_blank">smeenai@fb.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">It's more of a valgrind issue than an LLD issue, but you can work around it by linking with --no-rosegment<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in"><b><span style="font-size:12pt;color:black">From:
</span></b><span style="font-size:12pt;color:black">llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>> on behalf of Andrew Kelley via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>><br>
<b>Reply-To: </b>Andrew Kelley <<a href="mailto:superjoe30@gmail.com" target="_blank">superjoe30@gmail.com</a>><br>
<b>Date: </b>Thursday, April 5, 2018 at 2:14 PM<br>
<b>To: </b>LLVM Dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>><br>
<b>Subject: </b>[llvm-dev] can valgrind read LLD's debug info?<u></u><u></u></span></p>
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<a name="m_-2122909633160941005_m_-4491447127625396845_m_-1756913145478988886__MailOriginalBody">I just filed </a><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D37021&d=DwMFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=LOIzu9sn31pmykUwYH1_wAigCpxv33qUDNdmOrmGop4&s=2_EmscX6fjQZR0pF1CQWKUPDgpBLCJhFfnOvlkivJBE&e=" target="_blank"><span>https://bugs.llvm.org/show_bug.cgi?id=37021</span><span></span></a><span><u></u><u></u></span></p>
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<span>There was another bug that seems related to this which is
</span><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__bugs.llvm.org_show-5Fbug.cgi-3Fid-3D35032&d=DwMFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=LOIzu9sn31pmykUwYH1_wAigCpxv33qUDNdmOrmGop4&s=c8bjnWV_NwOLITc1Tc5dCjJC88BhCt86girLjAbXTbk&e=" target="_blank"><span>https://bugs.llvm.org/show_bug.cgi?id=35032</span><span></span></a><span>
but that one is marked fixed. But this seems to be an issue in trunk.<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:0.5in"><span>Is this a known issue?<u></u><u></u></span></p>
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