Le 28/07/2016 à 19:45, Eduardo Horvath a écrit :
On Thu, 28 Jul 2016, Maxime Villard wrote:Currently, there is no real way to make sure a userland process won't be able to allocate the NULL page. There is this attempt [1], but it has two major issues.I don't think this is a good idea. You should leave this to the pmap layer rather than polluting UVM. There are some architectures that need to have page zero mapped in for various reasons.
No. Quite on the contrary. UVM should handle that, instead of polluting pmap. You are saying that some architectures need the NULL page. That's fine, since #define __USER_VA0_IS_SAFE is architecture-dependent. For your information, __USER_VA0_IS_SAFE is never set, so clearly, no one needs the NULL page.