linux-kernel - Re: [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 25 Sep 2020 14:17:13 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Jethro Beekman <jethro@...tanix.com>
Cc:     Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Andy Lutomirski <luto@...capital.net>,
        Cedric Xing <cedric.xing@...el.com>, akpm@...ux-foundation.org,
        andriy.shevchenko@...ux.intel.com, asapek@...gle.com,
        chenalexchen@...gle.com, conradparker@...gle.com,
        cyhanish@...gle.com, dave.hansen@...el.com, haitao.huang@...el.com,
        josh@...htriplett.org, kai.huang@...el.com, kai.svahn@...el.com,
        kmoy@...gle.com, ludloff@...gle.com, luto@...nel.org,
        nhorman@...hat.com, npmccallum@...hat.com, puiterwijk@...hat.com,
        rientjes@...gle.com, tglx@...utronix.de, yaozhangx@...gle.com
Subject: Re: [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX
 enclave call

On Fri, Sep 25, 2020 at 10:39:58AM +0200, Jethro Beekman wrote:
> On 2020-09-25 03:00, Jarkko Sakkinen wrote:
> > End result:
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-sgx.git/tree/arch/x86/include/uapi/asm/sgx.h
> > 
> > I'm wondering this sentence:
> > 
> > "The calling convention is custom and does not follow System V x86-64 ABI."
> > 
> > AFAIK, now the vDSO is fully C-callable but waiting for feedback before
> > removing it.
> 
> It's C-callable *iff your enclave follows the System V x86-64 ABI*. In
> addition, all registers not clobbered by the SGX ISA are passed to the
> enclave, not just those specified as parameter passing registers in
> the ABI. This is intentional to make the vDSO function usable in
> applications that use the current flexibility of ENCLU.

Hold on, I really want to fix this bit of documentation before sending
any new version, so I'll explain how I understand it.

I think it is just SystemV ABI call with six parameters in the usual
GPRs (rdi, rsi, rdx, rcx, r8, r9).

I'm looking at vdso_sgx_enter_enclave.

What I'm not getting?

> --
> Jethro Beekman | Fortanix

/Jarkko