On 18.02.2016 21:47, Tony Luck wrote: > Make use of the EXTABLE_FAULT exception table entries to write > a kernel copy routine that doesn't crash the system if it > encounters a machine check. Prime use case for this is to copy > from large arrays of non-volatile memory used as storage. > > We have to use an unrolled copy loop for now because current > hardware implementations treat a machine check in "rep mov" > as fatal. When that is fixed we can simplify. > > Signed-off-by: Tony Luck <tony.l...@intel.com> > --- > > Is this what we want now? Return type is a "bool". True means > that we copied OK, false means that it didn't (this is all that > Dan says that he needs). Dropped all the complex code to figure > out how many bytes we didn't copy as Linus says this isn't the > right place to do this (and besides we should just make "rep mov" > > + > + /* Copy successful. Return true */ > +.L_done_memcpy_trap: > + xorq %rax, %rax > + ret > +ENDPROC(memcpy_mcsafe) > + > + .section .fixup, "ax" > + /* Return false for any failure */ > +.L_memcpy_mcsafe_fail: > + mov $1, %rax > + ret > + > But you return 0 == false for success and 1 == true for failure.
--Mika
