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: Mon, 08 Jun 2009 10:17:51 +0900 From: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com> To: Huang Ying <ying.huang@...el.com> CC: Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, Andi Kleen <ak@...ux.intel.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH -v4] x86: MCE: Re-implement MCE log ring buffer as per-CPU ring buffer Huang Ying wrote: > On Fri, 2009-06-05 at 16:28 +0800, Hidetoshi Seto wrote: >> Huang Ying wrote: >>> On Fri, 2009-06-05 at 15:01 +0800, Hidetoshi Seto wrote: >>>> Huang Ying wrote: >>>>> struct mce_log { >>>>> - char signature[12]; /* "MACHINECHECK" */ >>>>> + char signature[12]; /* "MACHINECHEC2" */ >>>>> unsigned len; /* = MCE_LOG_LEN */ >>>>> - unsigned next; >>>>> unsigned flags; >>>>> unsigned pad0; >>>>> - struct mce entry[MCE_LOG_LEN]; >>>>> + struct mce_log_cpu *mcelog_cpus; >>>>> }; >>>> What is this *mcelog_cpus to be used for? >>>> It seems it will point one of per-CPU buffers (maybe cpu#0's buffer) >>>> if I have read the following mce_log_init() correctly. >>> It is mainly used by something like kdump, which can search >>> "MACHINECHEC2", and analyze mce_log. mcelog_cpus can help kdump find the >>> real mcelog storage. >> Hum, but it help tools only to find one of buffers, not to find all. >> >> I think it would be better help for tools if we have another signature >> on struct mce_log_cpu, e.g.: >> >> +struct mce_log_cpu { >> + char signature[**]; /* "MCE_LOG_CPU_VER_1" or so */ >> + __u32 cpuid; /* cpuid or extcpu, same as struct mce */ >> + int head; >> + int tail; >> + unsigned long flags; >> + struct mce entry[MCE_LOG_LEN]; >> +}; >> >> How about this? > > + mcelog.mcelog_cpus = &per_cpu_var(mce_log_cpus); > > So mcelog.mcelog_cpus are pointed to the buffers of all CPUs, not just > that of one CPU. You can find them by analyzing PER cpu data structure. I thought that the signature is used to find the structure without such analyzing. If a tool can analyze PER cpu data, then it likely know where the mce_log_cpu is, so mcelog.mcelog_cpus will not be required. #define per_cpu_var(var) per_cpu__##var #define per_cpu(var, cpu) \ (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu))) OK, I have mistook per_cpu_var() for per_cpu(). Then mcelog.mcelog_cpus does not point any of the buffers, but tells where the buffer is locating in each of PER cpu data. Tools have to get per_cpu_offset(cpu) to know where the PER cpu data allocated. According to pcpu_alloc_bootmem(), it might consider NUMA. Anyway It will take a bit more effort. So still I think the mcelog.mcelog_cpus is mostly pointless. Thanks, H.Seto -- 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