linux-kernel - Re: [PATCH 5/6] x86/vdso: Use CFI macros in __vdso_sgx_enter

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Message-ID: <dc1ce226-9fdc-4a1e-9984-3b968b70681f@oracle.com>
Date: Tue, 29 Apr 2025 10:52:50 -0700
From: Indu Bhagat <indu.bhagat@...cle.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jens Remus
 <jremus@...ux.ibm.com>, x86@...nel.org,
        Peter Zijlstra
 <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 5/6] x86/vdso: Use CFI macros in
 __vdso_sgx_enter_enclave()

On 4/28/25 10:10 AM, Josh Poimboeuf wrote:
> On Mon, Apr 28, 2025 at 09:17:01AM -0700, Josh Poimboeuf wrote:
>> On Fri, Apr 25, 2025 at 04:22:22PM -0700, Indu Bhagat wrote:
>>> On 4/24/25 7:37 PM, Steven Rostedt wrote:
>>>> From: Josh Poimboeuf <jpoimboe@...nel.org>
>>>>
>>>> Use the CFI macros instead of the raw .cfi_* directives to be consistent
>>>> with the rest of the VDSO asm.  It's also easier on the eyes.
>>>>
>>>> No functional changes.
>>>>
>>>
>>> Although unrelated to the current intent of the patch, a question:
>>>
>>>    Why does the stub after .Linvoke_userspace_handler in vsgs.S not have CFI
>>> directives ?
>>
>> Yeah, looks like that stack alignment code needs some CFI.
> 
> Actually, this function uses a frame pointer so I think the stack
> pointer alignment shouldn't affect the CFI?
> 

You are right.  rbx is already handled too with the required CFI in the 
prologue.