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Date:   Fri, 25 Sep 2020 10:14:41 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, x86@kernel.org,
        linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org,
        Andy Lutomirski <luto@amacapital.net>,
        Jethro Beekman <jethro@fortanix.com>,
        Cedric Xing <cedric.xing@intel.com>, akpm@linux-foundation.org,
        andriy.shevchenko@linux.intel.com, asapek@google.com,
        chenalexchen@google.com, conradparker@google.com,
        cyhanish@google.com, dave.hansen@intel.com, haitao.huang@intel.com,
        josh@joshtriplett.org, kai.huang@intel.com, kai.svahn@intel.com,
        kmoy@google.com, ludloff@google.com, luto@kernel.org,
        nhorman@redhat.com, npmccallum@redhat.com, puiterwijk@redhat.com,
        rientjes@google.com, tglx@linutronix.de, yaozhangx@google.com
Subject: Re: [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX
 enclave call
Message-ID: <20200925081441.GF16872@zn.tnic>
References: <20200915112842.897265-1-jarkko.sakkinen@linux.intel.com>
 <20200915112842.897265-22-jarkko.sakkinen@linux.intel.com>
 <20200924180407.GO5030@zn.tnic>
 <20200925003808.GB20333@linux.intel.com>
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In-Reply-To: <20200925003808.GB20333@linux.intel.com>
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On Thu, Sep 24, 2020 at 05:38:10PM -0700, Sean Christopherson wrote:
> > Why not simply
> > 
> > arch/x86/entry/vdso/sgx.S
> > 
> > ?
> 
> I really like typing?

I'll say.

> Yes, to call out that there's a field there, but a field that the vDSO should
> never touch.

You wanna enforce that in the vdso code?

Because if it is there, luserspace will touch it.

> > > +#define SGX_ENCLAVE_RUN_EXCEPTION	4*8
> > > +
> > > +#define SGX_SYNCHRONOUS_EXIT		0
> > > +#define SGX_EXCEPTION_EXIT		1
> > 
> > Those are in ...uapi/asm/sgx.h too. Unify?
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

What about this here?

> > Are the CFI annotations for userspace?
> 
> Yes, though that's a 90% confident "yes".

Looks like we wanna support it:

f24f91088427 ("x86/vdso: Define BUILD_VDSO while building and emit .eh_frame in asm")

> Argh, it's actually supposed to be TCS, SGX_ENCLAVE_RUN_TSC is the one that's
> wrong.

Whoopsie :-)

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette