From: Thomas Gleixner <tglx@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>, Dmitry Voytik <voytikd@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>,
linux-toolchains@vger.kernel.org,
Alexander Potapenko <glider@google.com>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ankur Arora <ankur.a.arora@oracle.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
Marco Elver <elver@google.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
llvm@lists.linux.dev
Subject: Re: [PATCH] x86/mm: fix objtool failure with KMSAN enabled
Date: Thu, 02 Jul 2026 21:46:33 +0200 [thread overview]
Message-ID: <87se61npie.ffs@fw13> (raw)
In-Reply-To: <20260702111550.GH751831@noisy.programming.kicks-ass.net>
On Thu, Jul 02 2026 at 13:15, Peter Zijlstra wrote:
> A quick test with folio_zero_user() seems to suggest the
> ASM_CALL_CONSTRAINT movement (your patch) generates the same code for
> defconfg as does the unmodified code. The change from the thread linked
> above (input constraint on __builtin_frame_address(0)) generates
> different code.
>
> A third option is to force FRAME_POINTER=y for KMSAN builds -- for now,
> until clang is taught to be less insane.
With FRAME_POINTER=y I get now with clang-22
vmlinux.o: warning: objtool: folio_zero_user+0xa7b: stack state mismatch: reg1[4]=-1+0 reg2[4]=-2-336
vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x64: relocation to !ENDBR: machine_kexec_prepare+0x8f0
That's with your objtool patch applied. When I remove that then the
folio_zero_user one goes away. The relocation to !ENDBR stays.
Oh well...
next prev parent reply other threads:[~2026-07-03 0:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-01 12:51 [PATCH] x86/mm: fix objtool failure with KMSAN enabled Dmitry Voytik
2026-07-01 13:18 ` Alexander Potapenko
2026-07-01 14:45 ` Dmitry Voytik
2026-07-01 15:15 ` Alexander Potapenko
[not found] ` <20260702025342.GJakXStrsCmIRnEwFD@fat_crate.local>
[not found] ` <CAAX90H0V-=Gy1FyBT9qop2=RvhBxbOPLu6+DYpPH2pTehT=nRw@mail.gmail.com>
[not found] ` <20260702111550.GH751831@noisy.programming.kicks-ass.net>
2026-07-02 19:46 ` Thomas Gleixner [this message]
2026-07-02 20:05 ` Thomas Gleixner
2026-07-03 10:34 ` Dmitry Voytik
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