linux-kernel - Re: [PATCH v21 24/28] selftests/x86: Add a selftest for SGX

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Date:   Fri, 16 Aug 2019 18:51:36 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Xing, Cedric" <cedric.xing@...el.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-sgx@...r.kernel.org, akpm@...ux-foundation.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        nhorman@...hat.com, npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...el.com,
        andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
        kai.svahn@...el.com, bp@...en8.de, josh@...htriplett.org,
        luto@...nel.org, kai.huang@...el.com, rientjes@...gle.com
Subject: Re: [PATCH v21 24/28] selftests/x86: Add a selftest for SGX

On Fri, Aug 16, 2019 at 06:43:44PM +0300, Jarkko Sakkinen wrote:
> On Wed, Jul 17, 2019 at 03:37:03PM -0700, Xing, Cedric wrote:
> > > +$(OUTPUT)/encl.bin: $(OUTPUT)/encl.elf $(OUTPUT)/sgxsign
> > > +	objcopy --remove-section=.got.plt -O binary $< $@
> > 
> > .got.plt section will never be present for statically linked binaries.
> 
> You are right that it should not be there because the enclave does not
> use any library calls. And if it did, we would want to assert that and
> fail the compilation if it is the case.
> 
> Assuming that .got.plt can never exist in a static binary, however, is
> simply not true. A common example are library calls such as strncpy().
> The default handler selects the fastest implementation and substitutes
> that to the GOT.
> 
> The right way to fix this is to assert it in the linker script.

In addition, objcopy should be replaced with $(OBJCOPY).

/Jarkko