On Thu, Apr 30, 2020 at 12:23 PM Luck, Tony <tony.luck(a)intel.com> wrote:
On Thu, Apr 30, 2020 at 11:42:20AM -0700, Andy Lutomirski wrote:
> I suppose there could be a consistent naming like this:
> copy_from_unchecked_kernel_address() [what probe_kernel_read() is]
> copy_to_unchecked_kernel_address() [what probe_kernel_write() is]
> copy_from_fallible() [from a kernel address that can fail to a kernel
> address that can't fail]
> copy_to_fallible() [the opposite, but hopefully identical to memcpy() on x86]
> These names are fairly verbose and could probably be improved.
try_copy_catch(void *dst, void *src, size_t count, int *fault)
returns number of bytes not-copied (like copy_to_user etc).
if return is not zero, "fault" tells you what type of fault
cause the early stop (#PF, #MC).
I do like try_copy_catch() for the case when neither of the buffers
are __user (like in the pmem driver) and _copy_to_iter_fallible()
(plus all the helpers it implies) for the other cases.
...because the mmu-fault handling is an aspect of "_user" and fallible
implies other source fault reasons. It does leave a gap if an
architecture has a concept of a fallible write, but that seems like
something that will be handled asynchronously and not subject to this