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 09:32:37 +0100 [thread overview]
Message-ID: <Y9jSJUwNlXSpV3uM@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230130135354.27674-1-kirill.shutemov@linux.intel.com>
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.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Fixes: c30c4b2555ba ("x86/tdx: Refactor __tdx_hypercall() to allow pass down more arguments")
> Link: https://lore.kernel.org/all/202301290255.buUBs99R-lkp@intel.com
> Reported-by: kernel test robot <lkp@intel.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> ---
>
> The patch is against tip/x86/tdx. tip/sched/core removes
> TDX_HCALL_ISSUE_STI. The trird hunk of the patch is not relevant
> after that.
Right, this should work. But it does leave me wondering, should we
perhaps strive to completely remove the flags thing and move to
__tdx_hypercall() and __tdx_hypercall_ret() or something? That is,
simply have two different functions, one with and one without return
data.
It should be trivial to generate that without actual code duplication.
next prev parent reply other threads:[~2023-01-31 8:32 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 [this message]
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
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