lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Tue, 19 Sep 2023 10:28:47 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Xin Li <xin3.li@...el.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        linux-hyperv@...r.kernel.org, kvm@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, luto@...nel.org,
        pbonzini@...hat.com, seanjc@...gle.com, peterz@...radead.org,
        jgross@...e.com, ravi.v.shankar@...el.com, mhiramat@...nel.org,
        andrew.cooper3@...rix.com, jiangshanlai@...il.com
Subject: Re: [PATCH v10 36/38] x86/fred: Add fred_syscall_init()

On Wed, Sep 13 2023 at 21:48, Xin Li wrote:
> +static inline void fred_syscall_init(void)
> +{
> +	/*
> +	 * Per FRED spec 5.0, FRED uses the ring 3 FRED entrypoint for SYSCALL
> +	 * and SYSENTER, and ERETU is the only legit instruction to return to
> +	 * ring 3, as a result there is _no_ need to setup the SYSCALL and
> +	 * SYSENTER MSRs.
> +	 *
> +	 * Note, both sysexit and sysret cause #UD when FRED is enabled.
> +	 */
> +	wrmsrl(MSR_LSTAR, 0ULL);
> +	wrmsrl_cstar(0ULL);

That write is pointless. See the comment in wrmsrl_cstar().

Thanks,

        tglx

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ