linux-kernel - RE: [RESEND PATCH 2/6] x86/traps: add a system interrupt table for system interrupt dispatch

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Message-ID: <BN6PR1101MB216109C51162ABB27C8AA735A8019@BN6PR1101MB2161.namprd11.prod.outlook.com>
Date:   Thu, 10 Nov 2022 23:00:51 +0000
From:   "Li, Xin3" <xin3.li@...el.com>
To:     Nathan Chancellor <nathan@...nel.org>
CC:     Peter Zijlstra <peterz@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Kees Cook <keescook@...omium.org>
Subject: RE: [RESEND PATCH 2/6] x86/traps: add a system interrupt table for
 system interrupt dispatch

> > > > > +#pragma GCC diagnostic push
> > > > > +#pragma GCC diagnostic ignored "-Wcast-function-type"
> > > >
> > > > How does this not break CFI ?
> > >
> > > I wasn't aware of it, will check.
> >
> > CFI needs $(cc-option,-fsanitize=kcfi), which, reported on LWN on Jun,
> > 2002, had not yet landed in the LLVM mainline (I'm using GCC).  So
> > looks we are replying on people keeping an eye on it to make sure it's not
> broken?
> 
> Well, the entire point of the warning that you are disabling here is to catch
> potential CFI failures at compile time, rather than run time :)

Oh, of course I didn't intend to be opposed to CFI.

> 
> Clang also has -Wcast-function-type-strict, which Gustavo and Kees are working
> on getting enabled, so that even more CFI failures can be caught at compile
> time.
> 
> https://github.com/ClangBuiltLinux/linux/issues/1724
> https://lore.kernel.org/all/?q=-Wcast-function-type-strict
> 
> Cheers,
> Nathan