Make cpu_get_real_ticks use mfspr
PowerPC CPUs have had two ways to read the time base for quite some time now. They provide it using the mfspr instruction or - if a special bit is set in that opcode - using mftb. For timekeeping we're currently using mftb. While trying to get Qemu up and running on an e500v2 system, I stumbled over the CPU not supporting mftbu. It just throws an illegal instruction trap. So let's read the SPR values instead. All PPC CPUs should support them anyways. I tested this patch on an e500v2 system where it makes qemu work and on my 970MP system with 32-bit user space where everything still works with this patch applied. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: malc <av1474@comtv.ru>
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@ -98,9 +98,9 @@ static inline int64_t cpu_get_real_ticks(void)
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#else
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/* http://ozlabs.org/pipermail/linuxppc-dev/1999-October/003889.html */
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unsigned long junk;
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__asm__ __volatile__ ("mftbu %1\n\t"
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"mftb %L0\n\t"
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"mftbu %0\n\t"
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__asm__ __volatile__ ("mfspr %1,269\n\t" /* mftbu */
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"mfspr %L0,268\n\t" /* mftb */
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"mfspr %0,269\n\t" /* mftbu */
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"cmpw %0,%1\n\t"
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"bne $-16"
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: "=r" (retval), "=r" (junk));
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