20 Feb
2019
20 Feb
'19
2:47 p.m.
On Wed, 20 Feb 2019 14:57:31 +0100 Jann Horn jannh@google.com wrote:
(*) BTW, there is another concern to use _from_user APIs in kprobe. Are those APIs might sleep??
If you want to access userspace without sleeping, and ignore data in non-present pages, you can do `pagefault_disable(); err = __copy_from_user_inatomic(...); pagefault_enable();`. (Actually, maybe the kernel should have a helper for that...)
I was about to say pretty much the same thing (about using _inatomic()), but yeah, we should also have a helper function if we don't already to include the page_fault_disable/enable() too.
-- Steve