linux-kernel - Re: [PATCH v1 1/1] x86/fred/signal: Prevent single-step upon ERETU completion

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Message-ID: <84724098-adaf-4e35-9289-6c8c1aac1056@zytor.com>
Date: Thu, 22 May 2025 23:24:18 -0700
From: Xin Li <xin@...or.com>
To: Dave Hansen <dave.hansen@...el.com>, kernel test robot <lkp@...el.com>,
        linux-kernel@...r.kernel.org
Cc: oe-kbuild-all@...ts.linux.dev, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, peterz@...radead.org, andrew.cooper3@...rix.com,
        stable@...r.kernel.org
Subject: Re: [PATCH v1 1/1] x86/fred/signal: Prevent single-step upon ERETU
 completion

On 5/22/2025 10:54 AM, Dave Hansen wrote:
> On 5/22/25 10:33, Xin Li wrote:
>>>>> arch/x86/include/asm/sighandling.h:44:21: error: 'struct pt_regs'
>>>>> has no member named 'fred_ss'
>>>         44 |                 regs->fred_ss.swevent = 0;
>>>            |                     ^~
>>>
>>
>> Hmm, this statement is under IS_ENABLED(CONFIG_X86_FRED), which should
> 
> The compiler still _compiles_ unreachable statements:
> 
> 	if (0)
> 		foo = bar.bar;
> 
> An #ifdef will keep the compiler out completely, of course. That's
> probably the best thing in this case, especially since it'll be tucked
> away in a header.

Thanks a lot for the explanation.

     Xin