From: Dave Hansen <dave.hansen@intel.com>
To: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Robert Gill <rtgill82@gmail.com>,
Jari Ruusu <jariruusu@protonmail.com>,
Brian Gerst <brgerst@gmail.com>,
"Linux regression tracking (Thorsten Leemhuis)"
<regressions@leemhuis.info>,
antonio.gomez.iglesias@linux.intel.com,
daniel.sneddon@linux.intel.com, stable@vger.kernel.org
Subject: Re: [PATCH v5] x86/entry_32: Use stack segment selector for VERW operand
Date: Thu, 29 Aug 2024 15:28:13 -0700 [thread overview]
Message-ID: <cdcc5b91-321b-4e33-9a86-829b8f632ae6@intel.com> (raw)
In-Reply-To: <20240711-fix-dosemu-vm86-v5-1-e87dcd7368aa@linux.intel.com>
On 7/11/24 15:03, Pawan Gupta wrote:
> +/*
> + * Safer version of CLEAR_CPU_BUFFERS that uses %ss to reference VERW operand
> + * mds_verw_sel. This ensures VERW will not #GP for an arbitrary user %ds.
> + */
> +.macro CLEAR_CPU_BUFFERS_SAFE
> + ALTERNATIVE "", __stringify(verw %ss:_ASM_RIP(mds_verw_sel)), X86_FEATURE_CLEAR_CPU_BUF
> +.endm
One other thing...
Instead of making a "_SAFE" variant, let's just make the 32-bit version
always safe.
Also, is there any downside to using %ss: on 64-bit? If not, let's just
update the one and only CLEAR_CPU_BUFFERS use %ss:.
next prev parent reply other threads:[~2024-08-29 22:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-11 22:03 [PATCH v5] x86/entry_32: Use stack segment selector for VERW operand Pawan Gupta
2024-08-29 22:28 ` Dave Hansen [this message]
2024-08-29 23:04 ` Pawan Gupta
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