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([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id 10-20020a170906318a00b0072aac739089sm1942032ejy.98.2022.07.15.04.35.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Jul 2022 04:35:18 -0700 (PDT) Message-ID: <7b3ccb3e-174b-6f31-d875-452082262906@redhat.com> Date: Fri, 15 Jul 2022 13:35:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-US To: Linus Torvalds , Peter Zijlstra Cc: Boris Petkov , Guenter Roeck , Thadeu Lima de Souza Cascardo , Greg Kroah-Hartman , Naresh Kamboju , Florian Fainelli , kvm list , Andrew Morton , Dave Hansen , stable , Linux Kernel Mailing List , Pavel Machek , Jon Hunter , Sudip Mukherjee , Slade Watkins , patches@kernelci.org, Sean Christopherson , Shuah Khan , Ingo Molnar , Thomas Gleixner , X86 ML , lkft-triage@lists.linaro.org, =?UTF-8?Q?Alex_Benn=c3=a9e?= , "H. Peter Anvin" , Anders Roxell References: <20220712183238.844813653@linuxfoundation.org> <6b4337f4-d1de-7ba3-14e8-3ad0f9b18788@redhat.com> <8BEC3365-FC09-46C5-8211-518657C0308E@alien8.de> From: Paolo Bonzini Subject: Re: [PATCH 5.15 00/78] 5.15.55-rc1 review In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/14/22 20:16, Linus Torvalds wrote: > Oh, btw, how bad would it be to just do > > #define FASTOP_SIZE 16 > static_assert(FASTOP_SIZE >= FASTOP_LENGTH) Yeah, for 32 I might have some (probably irrational) qualms, but 16 is not worth the trouble. Given 3 bytes for ENDBR, 5 for the return thunk and 1 for the straight line speculation INT3, there are 7 bytes left and only 4 are currently used (for instructions encoded as "66 0f xx xx"). So FASTOP_SIZE at SETCC_ALIGN can indeed be 16 unconditionally. Paolo