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: Sat, 28 Nov 2015 14:13:29 +0300 From: Nikita Yushchenko <nyushchenko@....rtsoft.ru> To: Russell King - ARM Linux <linux@....linux.org.uk> CC: kuznetsovg@....rtsoft.ru, Vladimir Murzin <vladimir.murzin@....com>, Ian Campbell <ian.campbell@...rix.com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Mason <slash.tmp@...e.fr>, Will Deacon <will.deacon@....com>, Paul Kocialkowski <contact@...lk.fr>, linux-kernel@...r.kernel.org, Masahiro Yamada <yamada.m@...panasonic.com>, Pavel Machek <pavel@....cz>, linux-arm-kernel@...ts.infradead.org Subject: Re: [RFC/PATCH] arm: do not skip SMP init calls on SMP_ON_UP case >> Not sure I understand logic behind this. With the current code, >> resulting cpu_possible_mask depends on CONFIG_SMP_ON_UP: >> - if it is set, cpu_possible_mask contains (0 1), as initialized in >> arm_dt_init_cpu_maps() >> - if it is not set, cpu_possible_mask contains (0), since >> imx_smp_init_cpus() removes 1 from there. > > Right, adding debug to arch/arm/kernel/setup.c, just before the > "if (is_smp())" shows: > > is_smp() 0 possible 3 present 1 online 1 > > which is totally wrong: if is_smp() is false, we should not be setting > up any possible CPUs. See a patch below to fix that. > > However, this doesn't matter much, because the code in setup.c won't > initialise the SMP operations struct ... But cpu start code is not the only place in the kernel that uses cpu_present_mask. Are you sure that running with invalid cpu_present_mask has no side effects? > Here's the patch to fix the DT code, which should not be setting > present CPUs when is_smp() is false. I see that this fixes the issue as well. But I still don't understand rationale behind all these is_smp() checks. This makes init sequence different with and without CONFIG_SMP_ON_UP. Isn't kernel intended to run ok without CONFIG_SMP_ON_UP? And if yes - then why not run the same init sequence in both cases? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists