> Date: Tue, 15 Mar 2011 14:22:16 +0100
> From: Aleksander Piotrowski <[email protected]>
>
> hi mark
>
> i have signal 4, Illegal instruction crash on sparc64 with security/botan
> (required by newer devel/monotone). it looks like they are trying to get time
> from hardware timer using some funny asm's. sparc64 and asm are rocket
> science for me,
> that's why i'm asking for your help :-)
>
> here goes method body that, according to gdb, is our culprit. and the exact
> line is
>
> asm volatile("rd %%tick, %0" : "=r" (rtc));
>
> is this enough info or shall i provide you with more context?
> thanks in advance,
Hi Alek,
On OpenBSD we disable access to %tick from userland. I think the idea
is to make it harder for people to perform timing attacks, and
therefore improve security. But I don't consider myself enough of a
security expert to be able to judge wethere that really helps. So I
CC'ed tech@ in the hope that a more knowledgable person will chime in.
Cheers,
Mark
> /*
> * Get the timestamp
> */
> u64bit Hardware_Timer::clock() const
> {
> u64bit rtc = 0;
>
> #if defined(BOTAN_TARGET_ARCH_IS_IA32) || defined(BOTAN_TARGET_ARCH_IS_AMD64)
> u32bit rtc_low = 0, rtc_high = 0;
> asm volatile("rdtsc" : "=d" (rtc_high), "=a" (rtc_low));
> rtc = (static_cast<u64bit>(rtc_high) << 32) | rtc_low;
>
> #elif defined(BOTAN_TARGET_ARCH_IS_PPC) || defined(BOTAN_TARGET_ARCH_IS_PPC64)
> u32bit rtc_low = 0, rtc_high = 0;
> asm volatile("mftbu %0; mftb %1" : "=r" (rtc_high), "=r" (rtc_low));
> rtc = (static_cast<u64bit>(rtc_high) << 32) | rtc_low;
>
> #elif defined(BOTAN_TARGET_ARCH_IS_ALPHA)
> asm volatile("rpcc %0" : "=r" (rtc));
>
> #elif defined(BOTAN_TARGET_ARCH_IS_SPARC64)
> asm volatile("rd %%tick, %0" : "=r" (rtc));
>
> #elif defined(BOTAN_TARGET_ARCH_IS_IA64)
> asm volatile("mov %0=ar.itc" : "=r" (rtc));
>
> #elif defined(BOTAN_TARGET_ARCH_IS_S390X)
> asm volatile("stck 0(%0)" : : "a" (&rtc) : "memory", "cc");
>
> #elif defined(BOTAN_TARGET_ARCH_IS_HPPA)
> asm volatile("mfctl 16,%0" : "=r" (rtc)); // 64-bit only?
>
> #else
> #error "Unsure how to access hardware timer on this system"
> #endif
>
> return rtc;
> }
