On 11/08/2017 05:34 PM, Linus Torvalds wrote:
On Wed, Nov 8, 2017 at 8:14 AM, Denys Vlasenko <dvlasenk@xxxxxxxxxx> wrote:Can we avoid maintain emulation of these isns, by asking Wine to remove their use instead?If we ask the Wine people to remove the instruction use, that may mean that we can avoid the emulation in four or five _years_ once everybody has updated. But it wouldn't mean that we could avoid it today.
We can postpone enabling UMIP by default by a year or so. By this time, new Wine will be on majority of users' machines. Then, when kernels switch to enable UMIP by default, umip=0 kernel flag can be used if somebody for some reason updates their kernel but not Wine. This is much less code, and simpler code, than implementing SIDT et al emulation. Keep in mind that our SIDT emulation itself can turn out to be buggy, in the worst case it may end up having worse holes that SIDT isns was - what if it can be tricked into writing into arbitrary kernel address? -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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