FPU emul and segmentation fault bug
I remember a while back we had a problem with FPU emulation code which causes a segmentation fault. (Perhaps another symptom is bus error, but I am not 100% sure).
Apparently this problem is fixed in the recent kernel. However, it shows up again in SMP mode.
Does anybody remember details of the problem and the fix? I am afraid maybe something we did there is not SMP safe.
Thanks.
Jun
Quoted 9 lines · Jun Sun
I remember a while back we had a problem with FPU emulation code which causes a segmentation fault. (Perhaps another symptom is bus error, but I am not 100% sure).
Apparently this problem is fixed in the recent kernel. However, it shows up again in SMP mode.
Does anybody remember details of the problem and the fix? I am afraid maybe something we did there is not SMP safe.
That's most probably a SMP cache invalidation bug. What happens is that remote CPUs try to invalidate the same address range as a local CPU as well without any consideration that the active context of the remote CPU might be different from the local one. In combination with another bug this may actually crash the whole system.
Ralf