On 12/18/2015 05:23 PM, Jan Kiszka wrote: > Hi all, > > I know this is legacy code, but this is where we currently stumbled into > it, and maybe the same pattern also exists in 3.x: > > http://git.xenomai.org/xenomai-2.6.git/tree/ksrc/skins/posix/syscall.c#n1182 > > more precisely: > > return pse51_mutex_check_init(&umx->shadow_mutex, attr); > > Here we pass the userspace object for initialization to the core instead > of handing over the kernel shadow and then copying over the result. Is > there a reason for this? Could we have more of such cases? > > Background: SMAP detects and prevents any direct userspace memory access > on x86 except or those that are wrapped in stac() and clac() (which > toggle a bit in eflags). Generally a useful feature we should allow to > be enabled for robustness reasons. >
As far as 3.x is concerned, I don't think this direct access pattern is used there, this would have likely caused me some headaches for supporting the 32/64 mixed ABI models, and I don't remember of any such headache. At any rate, I don't see any reason to do this in 3.x. -- Philippe. _______________________________________________ Xenomai mailing list Xenomai@xenomai.org http://xenomai.org/mailman/listinfo/xenomai
