On Wed, Oct 07, 2020 at 08:01:42PM +0200, Daniel Vetter wrote: > I think it'd fix the bug, until someone wires ->access up for > drivers/gpu, or the next subsystem. This is also just for ptrace, so > we really don't care when we stall the vm badly and other silly > things. So I figured the somewhat ugly, but full generic solution is > the better one, so that people who want to be able to ptrace > read/write their iomem mmaps can just sprinkle this wherever they feel > like. > > But yeah if we go with most minimal fix, i.e. only trying to fix the > current users, then your thing should work and is simpler. But it > leaves the door open for future problems.
The only other idea I had was to fully make the 'vma of __iomem memory' some generic utility, completely take over the vm_ops. We did something like this in RDMA, what I found was even just implementing mmap() using the kernel helpers turned out to be pretty tricky, many drivers did it wrong in small ways. Jason
