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charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 0F86840007 X-Stat-Signature: xgbk5uc9hiyg53jeqieq49ktgjc3wgrp X-Rspam-User: X-HE-Tag: 1768851811-275315 X-HE-Meta: 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 1UDud9Y6 uTWAo54o9fy9mkCfMyMf4jyodUxYwEH2gD8/Nqic0oyUN0jFG/IDlxR9noBfQxku90L8YDpC8Tq+cE/YBKcFAPzvp/bm9XaQChkNYr3wjHo0LjSJuJG6ACQJEmy8zw7kgTrAEFM/CQ+5aUkSt2CIZLuM0t6cM3VxIl5DcLQoMIpYFvAwgX4W/LQ9eiK1cNF0DeVZxjIN11UrvIUKxuytjM8R1R82Oc+8dJMASmt585BNwYxPc5Yllso2lrbvbf4qDiLM7+UOF+HVEFa1Qaea2D7s3HR/y/Fh7/mjXEZ4WSY8W0nVriZ3iNaVCMsNzXzFg4Z5vt4OBeetKKe8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-01-19 at 17:33:35 +0100, Andrey Ryabinin wrote: >On 1/12/26 6:26 PM, Maciej Wieczor-Retman wrote: > >> =3D=3D=3D=3D=3D=3D=3D Compilation >> Clang was used to compile the series (make LLVM=3D1) since gcc doesn't >> seem to have support for KASAN tag-based compiler instrumentation on >> x86. >> > >It appears that GCC nominally supports this, but in practice it does not w= ork. >Here is a minimal reproducer: https://godbolt.org/z/s85e11T5r > >As far as I understand, calling a function through a tagged pointer is not >supported by the hardware, so GCC attempts to clear the tag before the cal= l. >This behavior seems to be inherited from the userspace implementation of H= WASan (-fsanitize=3Dhwaddress). > >I have filed a GCC bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?i= d=3D123696 > >For the kernel, we probably do not want this masking at all, as effectivel= y 99.9=E2=80=93100% >of function pointer calls are expected to be untagged anyway. > >Clang does not appear to do this, not even for userspace. Cool, thanks, nice to know why the kernel didn't start with gcc. I'm going to check in on the bug report every now and then and once it gets resolved I'll test if everything works as expected on both compilers. --=20 Kind regards Maciej Wiecz=C3=B3r-Retman