linux-kernel - Re: [PATCH v2 1/1] x86/fred/signal: Prevent single-step upon ERETU completion

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Message-ID: <ad8d3a12-25f3-4d57-8f34-950b7967f92b@citrix.com>
Date: Thu, 22 May 2025 18:53:16 +0100
From: Andrew Cooper <andrew.cooper3@...rix.com>
To: Dave Hansen <dave.hansen@...el.com>, "Xin Li (Intel)" <xin@...or.com>,
 linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 peterz@...radead.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/1] x86/fred/signal: Prevent single-step upon ERETU
 completion

On 22/05/2025 6:22 pm, Dave Hansen wrote:
> On 5/22/25 10:17, Xin Li (Intel) wrote:
>> Clear the software event flag in the augmented SS to prevent infinite
>> SIGTRAP handler loop if TF is used without an external debugger.
> Do you have a test case for this? It seems like the kind of thing we'd
> want in selftests/.

Hmm.

This was a behaviour intentionally changed in FRED so traps wouldn't get
lost if an exception where to occur.

What precise case is triggering this?

~Andrew