linux-kernel - Re: [PATCH v4 0/2] x86/fred: Prevent single-step upon ERETU completion

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Message-ID: <8264e653-6570-4c2a-a9a7-c4104da26f76@intel.com>
Date: Thu, 5 Jun 2025 12:32:29 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: "Xin Li (Intel)" <xin@...or.com>, <linux-kernel@...r.kernel.org>,
	<linux-kselftest@...r.kernel.org>
CC: <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
	<shuah@...nel.org>, <andrew.cooper3@...rix.com>
Subject: Re: [PATCH v4 0/2] x86/fred: Prevent single-step upon ERETU
 completion

On 6/5/2025 11:10 AM, Xin Li (Intel) wrote:

> 
> Xin Li (Intel) (2):
>   x86/fred/signal: Prevent single-step upon ERETU completion
>   selftests/x86: Add a test to detect infinite sigtrap handler loop
> 

I tested the patches on a machine that supports FRED. The results are as
expected:

FRED on  — no Fix   => FAIL
FRED off — no Fix   => PASS
FRED on  — with Fix => PASS
FRED off — with Fix => PASS

Tested-by: Sohil Mehta <sohil.mehta@...el.com>

Though, I haven't tested the 32-bit version of the selftest.

>  arch/x86/include/asm/sighandling.h         | 22 +++++
>  arch/x86/kernel/signal_32.c                |  4 +
>  arch/x86/kernel/signal_64.c                |  4 +
>  tools/testing/selftests/x86/Makefile       |  2 +-
>  tools/testing/selftests/x86/sigtrap_loop.c | 97 ++++++++++++++++++++++
>  5 files changed, 128 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/x86/sigtrap_loop.c
>