From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: "Xing, Cedric" <cedric.xing@intel.com>,
Nathaniel McCallum <npmccallum@redhat.com>,
Jethro Beekman <jethro@fortanix.com>,
Andy Lutomirski <luto@amacapital.net>,
linux-sgx@vger.kernel.org
Subject: Re: [PATCH for_v29 3/8] x86/sgx: vdso: Make __vdso_sgx_enter_enclave() callable from C code
Date: Fri, 20 Mar 2020 16:26:49 -0700 [thread overview]
Message-ID: <20200320232649.GG3866@linux.intel.com> (raw)
In-Reply-To: <20200320030700.GF183331@linux.intel.com>
On Fri, Mar 20, 2020 at 05:07:00AM +0200, Jarkko Sakkinen wrote:
> On Thu, Mar 19, 2020 at 01:11:45PM -0700, Sean Christopherson wrote:
> > On Thu, Mar 19, 2020 at 01:03:41PM -0700, Xing, Cedric wrote:
> > > On 3/18/2020 6:11 PM, Sean Christopherson wrote:
> > > > #endif
> > > > SYM_FUNC_START(__vdso_sgx_enter_enclave)
> > > > /* Prolog */
> > > >@@ -82,7 +84,9 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave)
> > > > .cfi_rel_offset %rbp, 0
> > > > mov %rsp, %rbp
> > > > .cfi_def_cfa_register %rbp
> > > >+ push %rbx
> > > A CFI directive is needed here:
> > >
> > > .cfi_rel_offset %rbx, -8
> >
> > Darn, I suspected as much, but wasn't 100% positive. Shouldn't have
> > hedged. :-)
> >
> > Is the rule of thumb for adding directives that one is needed any time
> > there is a new saved value of a register, or if the relative address of
> > the last saved value changes? Are CFI directives only used for
> > non-volatile registers?
>
> AFAIK the convention is just that if you push a register you need to
> offset it so that the FDE that is put into .eh_frame by GCC has the
> information from which locations of the stack the register values are
> copied.
>
> BTW, why use GCC-style ".L-mangled" label names instead of having more
> readable ones?
Readable as in dropping the .L part? E.g.
enclu_eenter_eresume:
I assumed we'd want to keep the local labels out of the symbols file, but
maybe getting them in there would be a good thing?
next prev parent reply other threads:[~2020-03-20 23:26 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 1:11 [PATCH for_v29 0/8] x86/sgx: Make vDSO callable from C Sean Christopherson
2020-03-19 1:11 ` [PATCH for_v29 1/8] x86/sgx: vdso: Remove an incorrect statement the enter enclave comment Sean Christopherson
2020-03-19 20:49 ` Jarkko Sakkinen
2020-03-19 1:11 ` [PATCH for_v29 2/8] x86/sgx: vdso: Make the %rsp fixup on return from handler relative Sean Christopherson
2020-03-20 2:39 ` Jarkko Sakkinen
2020-03-20 2:42 ` Jarkko Sakkinen
2020-03-19 1:11 ` [PATCH for_v29 3/8] x86/sgx: vdso: Make __vdso_sgx_enter_enclave() callable from C code Sean Christopherson
2020-03-19 20:03 ` Xing, Cedric
2020-03-19 20:11 ` Sean Christopherson
2020-03-20 3:07 ` Jarkko Sakkinen
2020-03-20 23:26 ` Sean Christopherson [this message]
2020-03-21 0:57 ` Jarkko Sakkinen
2020-03-19 1:11 ` [PATCH for_v29 4/8] x86/sgx: vdso: Define a typedef for __vdso_sgx_enter_enclave Sean Christopherson
2020-03-19 1:11 ` [PATCH for_v29 5/8] selftests/x86: sgx: Zero out @result before invoking vDSO sub-test Sean Christopherson
2020-03-19 1:11 ` [PATCH for_v29 6/8] selftests/x86: sgx: Pass EENTER to vDSO wrapper instead of hardcoding Sean Christopherson
2020-03-19 1:11 ` [PATCH for_v29 7/8] selftests/x86: sgx: Stop clobbering non-volatile registers Sean Christopherson
2020-03-19 1:11 ` [PATCH for_v29 8/8] selftests/x86: Add selftest to invoke __vsgx_enter_enclave() from C Sean Christopherson
2020-03-20 0:57 ` [PATCH for_v29 0/8] x86/sgx: Make vDSO callable " Jarkko Sakkinen
2020-03-20 23:25 ` Sean Christopherson
2020-03-21 0:55 ` Jarkko Sakkinen
2020-03-21 20:11 ` Sean Christopherson
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