From: Peter Zijlstra <peterz@infradead.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Elena Reshetova <elena.reshetova@intel.com>,
x86@kernel.org, linux-coco@lists.linux.dev,
linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH] x86/tdx: Do not corrupt frame-pointer in __tdx_hypercall()
Date: Tue, 31 Jan 2023 10:39:48 +0100 [thread overview]
Message-ID: <Y9jh5Gi/dH09ajQD@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230131083901.ssg5huno2lhrbmzg@box.shutemov.name>
On Tue, Jan 31, 2023 at 11:39:01AM +0300, Kirill A. Shutemov wrote:
> On Tue, Jan 31, 2023 at 09:34:12AM +0100, Peter Zijlstra wrote:
> > On Mon, Jan 30, 2023 at 04:53:54PM +0300, Kirill A. Shutemov wrote:
> > > If compiled with CONFIG_FRAME_POINTER=y, objtool in not happy that
> > > __tdx_hypercall() messes up RBP.
> > >
> > > objtool: __tdx_hypercall+0x7f: return with modified stack frame
> > >
> > > Rework the function to store TDX_HCALL_ flags on stack instead of RBP.
> >
> > Also, on IRC you mentioned that per TDX spec, BP is a valid argument
> > register too and you were going to raise this and get it fixed, TDX
> > hypercalls must not use BP to pass data.
>
> I've raised the question yesterday. No progress so far. It will take time
> to get it into the public spec.
Sure, just making sure it's not forgotten about. Thanks!
prev parent reply other threads:[~2023-01-31 9:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-30 13:53 [PATCH] x86/tdx: Do not corrupt frame-pointer in __tdx_hypercall() Kirill A. Shutemov
2023-01-31 8:32 ` Peter Zijlstra
2023-01-31 8:50 ` Kirill A. Shutemov
2023-01-31 8:34 ` Peter Zijlstra
2023-01-31 8:39 ` Kirill A. Shutemov
2023-01-31 9:39 ` Peter Zijlstra [this message]
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