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
| ||
|
Date: Fri, 11 Mar 2016 12:28:24 -0700 From: Toshi Kani <toshi.kani@....com> To: Borislav Petkov <bp@...en8.de> Cc: "mingo@...nel.org" <mingo@...nel.org>, "hpa@...or.com" <hpa@...or.com>, "tglx@...utronix.de" <tglx@...utronix.de>, "mcgrof@...e.com" <mcgrof@...e.com>, "jgross@...e.com" <jgross@...e.com>, "paul.gortmaker@...driver.com" <paul.gortmaker@...driver.com>, "x86@...nel.org" <x86@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table On Fri, 2016-03-11 at 16:54 +0100, Borislav Petkov wrote: > On Fri, Mar 11, 2016 at 09:27:40AM -0700, Toshi Kani wrote: > > How about pat_disable_setup()? It's only used for the disabled case, > > so I'd prefer to keep the word "disable". > > What for? > > Renaming pat_init() to pat_setup() is perfectly fine as it sets up PAT > after looking at pat_disabled() setting and after looking at the CPU > vendor. Sounds like a perfectly sane design to me. Sorry, I meant to say -- "How about renaming pat_disable_init() to pat_disable_setup()?" since I thought you had suggested to rename pat_disable_init() to pat_setup(). I am still in favor of having a separate setup func for the disabled case. > > Yes, calling pat_init() from pat_disable() works too. I changed it in > > this way because: > > - pat_bsp_init() calls pat_disabled() in an error case. It is simpler > > to avoid a recursive call to pat_init(). > > So do this: > > static inline void pat_disable(const char *reason) > { > if (!__pat_enabled) > return; Hmm... I do not think I understand this. When pat_bsp_init() calls pat_disable(), 'pat' has been set to the "Full PAT support" setup. So, we need to reset 'pat' to the "No PAT" setup. How is this handled in your case? > > - pat_bsp_init() has two different error paths, 1) call pat_disable() > > and return, and 2) goto done and call pat_init_cache_modes(). We can > > remove case 2) to keep the error handling consistent in this way. > > Above. > > > > Then you don't have to add yet another static disable_init_done but > > > rely on boot_cpu_done which gets set in pat_init(). > > > > Right, but it will do 'boot_cpu_done = true' twice, and this implicit > > recursive call may cause an issue in future if someone makes change > > carelessly. > > So move boot_cpu_done into pat_bsp_init() and make it protect that > function from a being called a second time. I think this leads more complication in the end. pat_init() covers (too) many scenarios already, and moving the disabled setup case out will simplify it, IMHO. Thanks, -Toshi
Powered by blists - more mailing lists