<div dir="ltr">Not at this stage -- no.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Jul 15, 2020 at 3:23 PM Zhaoshi Zheng <<a href="mailto:zhaoshiz@quicinc.com">zhaoshiz@quicinc.com</a>> wrote:<br></div><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">Mitch,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I forgot to ask: do you have any timeline on sharing it through Phabricator?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks,<u></u><u></u></p>
<p class="MsoNormal">Zhaoshi<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><b>From:</b> llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>> <b>On Behalf Of
</b>Zhaoshi Zheng via llvm-dev<br>
<b>Sent:</b> Tuesday, July 14, 2020 21:34<br>
<b>To:</b> Mitch Phillips <<a href="mailto:mitchp@google.com" target="_blank">mitchp@google.com</a>><br>
<b>Cc:</b> <a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>; Stephen Long <<a href="mailto:steplong@quicinc.com" target="_blank">steplong@quicinc.com</a>><br>
<b>Subject:</b> [EXT] Re: [llvm-dev] [MTE] Tagging Globals<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks for the update, Phillips.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Yes, please add me, Stephen and Ana (CCed) to Phabricator reviews.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Zhaoshi<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><b>From:</b> Mitch Phillips <<a href="mailto:mitchp@google.com" target="_blank">mitchp@google.com</a>>
<br>
<b>Sent:</b> Tuesday, July 14, 2020 19:10<br>
<b>To:</b> Zhaoshi Zheng <<a href="mailto:zhaoshiz@quicinc.com" target="_blank">zhaoshiz@quicinc.com</a>><br>
<b>Cc:</b> <a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>; Stephen Long <<a href="mailto:steplong@quicinc.com" target="_blank">steplong@quicinc.com</a>><br>
<b>Subject:</b> [EXT] Re: [llvm-dev] [MTE] Tagging Globals<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Hi Zhaoshi,<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Currently there's no global tagging instrumentation for MTE. We have a good idea about the implementation's design - but no patches are ready to be shared at this stage.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">If you'd like - I'd be more than happy to CC yourself and Stephen on any Phabricator reviews :).<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Tue, Jul 14, 2020 at 5:04 PM Zhaoshi Zheng via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">Hello,<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">We’re evaluating memory tagging (MTE) on some internal workloads.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">We noticed that stack variables are tagged by an instrumentation pass and heap objects are handled by the allocator (Scudo).<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">How about global variables? We tried a simple case using -march=armv8a+memtag -fsanitize=memtag, but found no tagging:<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Are we missing anything or tagging globals is still in progress?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal"><i>int global_array[16];</i><u></u><u></u></p>
<p class="MsoNormal"><i> </i><u></u><u></u></p>
<p class="MsoNormal"><i>int main(int argc, char **argv) {</i><u></u><u></u></p>
<p class="MsoNormal"><i> global_array[1] = 0;</i><u></u><u></u></p>
<p class="MsoNormal"><i> return global_array[argc + 16]; // BOOM</i><u></u><u></u></p>
<p class="MsoNormal"><i>}</i><u></u><u></u></p>
<p class="MsoNormal"><i> </i><u></u><u></u></p>
<p class="MsoNormal">clang++ -O1 --target=aarch64-linux -march=armv8.5a+memtag -fsanitize=memtag test.cpp -S -o test.s<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal"><i>main: // @main</i><u></u><u></u></p>
<p class="MsoNormal"><i>.Lmain$local:</i><u></u><u></u></p>
<p class="MsoNormal"><i>// %bb.0: // %entry</i><u></u><u></u></p>
<p class="MsoNormal"><i> adrp x8, global_array</i><u></u><u></u></p>
<p class="MsoNormal"><i> add x8, x8, :lo12:global_array</i><u></u><u></u></p>
<p class="MsoNormal"><i> str wzr, [x8, #4]</i><u></u><u></u></p>
<p class="MsoNormal"><i> add x8, x8, w0, sxtw #2</i><u></u><u></u></p>
<p class="MsoNormal"><i> ldr w0, [x8, #64]</i><u></u><u></u></p>
<p class="MsoNormal"><i> ret</i><u></u><u></u></p>
<p class="MsoNormal"><i>.Lfunc_end0:</i><u></u><u></u></p>
<p class="MsoNormal"><i> .size main, .Lfunc_end0-main</i><u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
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