Re: [systemd-devel] Antw: Re: rdrand generated with march=winchip-c6 in systemd-241
Am 13.05.19 um 09:10 schrieb Ulrich Windl: tedheadster schrieb am 11.05.2019 um 19:19 in Nachricht > : >> On Sat, May 11, 2019 at 12:30 PM Florian Weimer wrote: >>> Can you capture register contents at the point of the crash? >>> >>> Does this reproduce in a chroot? Maybe you can trace the whole thing >>> with a debugger. Does the crash reproduce if you single-step through >>> the whole function? >> >> Florian, >> I figured out the problem, I just haven't written code to fix it. >> The documentation I can find is silent about what is returned in %ecx >> and %ebx when calling cpuid function 0x0001 on IDT Winchip-C6 and >> Winchip2. >> >> I think %ecx should properly contain 0x, but it instead puts >> the 'auls' characters from cpuid function 0x (vendor string >> 'CentaurHauls') in %ecx: >> >> %ebx = 0x746e6543 = "Cent" >> %edx = 0x48727561 = "aurH" >> %ecx = 0x736c7561 = "auls" >> >> This sets bit 30 (0x736c7561) 'on', the 'supports rdrand' bit. >> >> So we have to code around the vendor and chip model in this case. >> Jeffrey Walton gave some coding examples I might consider >> (https://github.com/weidai11/cryptopp/blob/master/cpu.cpp#L380). > > > I didn't see the start of this thread, but is it another attempt to > re-implement /proc/cpuinfo's flags? can you please stop all that trolling? cpuid has *nothing* to do with /proc/cpuinfo https://en.wikipedia.org/wiki/CPUID The CPUID instruction (identified by a CPUID opcode) is a processor supplementary instruction ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] Antw: Re: rdrand generated with march=winchip-c6 in systemd-241
>>> tedheadster schrieb am 11.05.2019 um 19:19 in >>> Nachricht : > On Sat, May 11, 2019 at 12:30 PM Florian Weimer wrote: >> Can you capture register contents at the point of the crash? >> >> Does this reproduce in a chroot? Maybe you can trace the whole thing >> with a debugger. Does the crash reproduce if you single-step through >> the whole function? > > Florian, > I figured out the problem, I just haven't written code to fix it. > The documentation I can find is silent about what is returned in %ecx > and %ebx when calling cpuid function 0x0001 on IDT Winchip-C6 and > Winchip2. > > I think %ecx should properly contain 0x, but it instead puts > the 'auls' characters from cpuid function 0x (vendor string > 'CentaurHauls') in %ecx: > > %ebx = 0x746e6543 = "Cent" > %edx = 0x48727561 = "aurH" > %ecx = 0x736c7561 = "auls" > > This sets bit 30 (0x736c7561) 'on', the 'supports rdrand' bit. > > So we have to code around the vendor and chip model in this case. > Jeffrey Walton gave some coding examples I might consider > (https://github.com/weidai11/cryptopp/blob/master/cpu.cpp#L380). I didn't see the start of this thread, but is it another attempt to re-implement /proc/cpuinfo's flags? > > - Matthew > ___ > systemd-devel mailing list > systemd-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/systemd-devel ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
