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Date:   Fri, 11 Nov 2022 14:07:05 -0800
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     "Li, Xin3" <xin3.li@intel.com>,
        Peter Zijlstra <peterz@infradead.org>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
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        "tglx@linutronix.de" <tglx@linutronix.de>,
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        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "Tian, Kevin" <kevin.tian@intel.com>
Subject: =?US-ASCII?Q?RE=3A_=5BRESEND_PATCH_2/6=5D_x86/traps=3A_add_a_system?= =?US-ASCII?Q?_interrupt_table_for_system_interrupt_dispatch?=
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On November 10, 2022 11:55:22 AM PST, "Li, Xin3" <xin3=2Eli@intel=2Ecom> wr=
ote:
>> > Signed-off-by: H=2E Peter Anvin (Intel) <hpa@zytor=2Ecom>
>> > Signed-off-by: Xin Li <xin3=2Eli@intel=2Ecom>
>>=20
>> This is not a valid SOB, it would suggest hpa is the author, but he's n=
ot in in
>> From=2E
>
>HPA wrote the initial dispatch code for FRED, and I worked with him to
>refactor it for KVM/VMX NMI/IRQ dispatch=2E  So use SOB from both=2E  No?
>
>> > diff --git a/arch/x86/kernel/traps=2Ec b/arch/x86/kernel/traps=2Ec in=
dex
>> > 178015a820f0=2E=2E95dd917ef9ad 100644
>> > --- a/arch/x86/kernel/traps=2Ec
>> > +++ b/arch/x86/kernel/traps=2Ec
>> > @@ -1444,6 +1444,61 @@ DEFINE_IDTENTRY_SW(iret_error)  }  #endif
>> >
>> > +#define SYSV(x,y) [(x) - FIRST_SYSTEM_VECTOR] =3D
>> > +(system_interrupt_handler)y
>> > +
>> > +#pragma GCC diagnostic push
>> > +#pragma GCC diagnostic ignored "-Wcast-function-type"
>>=20
>> How does this not break CFI ?
>
>I wasn't aware of it, will check=2E
>

It doesn't break CFI because the arguments passed is always a strict super=
set of the ones expected and they are free enough that they are always pass=
ed in registers=2E