From: linux-rdma-owner@xxxxxxxxxxxxxxx <linux-rdma-owner@xxxxxxxxxxxxxxx> on behalf of Leon Romanovsky <leon@xxxxxxxxxx>
Sent: Monday, May 14, 2018 11:06 AM
> > >
> > > Thanks
> > Thanks for pointing these out. I was not familiar with this convention. However, the addresses
> > Which are printed below are the physical doorbell addresses which don't
> > Seem to fall into the category of the kernel pointers described in the article as the ones that should
> > Be protected. Using the %pk doesn't print the value correctly.
> > Thanks,
> Can you share the example code for such case? AFAIK, the %pK is actually
> censored equivalent of %px and that is equal to your %lx.
> Also prints of vma->vm_start and vma->vm_end are for sure not physical
> doorbells.
Modified the code as follows for comparison:
DP_DEBUG(dev, QEDR_MSG_INIT,
"mmap (pk) invoked with vm_start=0x%pk,x vm_end=0x%pk,vm_pgoff=0x%pk; dpi_start=0x%pk dpi_size=0x%x\n",
(void *)vma->vm_start, (void *)vma->vm_end, (void *)vma->vm_pgoff, (void *)dpi_start,
ucontext->dpi_size);
DP_DEBUG(dev, QEDR_MSG_INIT,
"mmap (px) invoked with vm_start=0x%px,x vm_end=0x%px,vm_pgoff=0x%px; dpi_start=0x%px dpi_size=0x%x\n",
(void *)vma->vm_start, (void *)vma->vm_end, (void *)vma->vm_pgoff, (void *)dpi_start,
ucontext->dpi_size);
DP_DEBUG(dev, QEDR_MSG_INIT,
"mmap invoked with vm_start=0x%lx,x vm_end=0x%lx,vm_pgoff=0x%lx; dpi_start=0x%lx dpi_size=0x%x\n",
vma->vm_start, vma->vm_end, vma->vm_pgoff, dpi_start,
ucontext->dpi_size);
and got the following output:
[32937.851202] (qedr1) INIT: mmap (pk) invoked with vm_start=0x000000009dacc20a,x vm_end=0x0000000040480bf1,vm_pgoff=0x00000000d9849dd6; dpi_start=0x00000000c74fd5ea dpi_size=0x2000
[32937.851203] (qedr1) INIT: mmap (px) invoked with vm_start=0x00007f20575ad000,x vm_end=0x00007f20575af000,vm_pgoff=0x0000000000091b03; dpi_start=0x0000000091b03000 dpi_size=0x2000
[32937.851205] (qedr1) INIT: mmap invoked with vm_start=0x7f20575ad000,x vm_end=0x7f20575af000,vm_pgoff=0x91b03; dpi_start=0x91b03000 dpi_size=0x2000
looks like the %pk gives hashed results similar to the %p even if the kptr_restrict is zero.
sysctl kernel/kptr_restrict
kernel.kptr_restrict = 0
> Thanks
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