On Fri, Jan 8, 2016 at 12:49 PM, Tony Luck <tony.luck@xxxxxxxxx> wrote: > Huge amounts of help from Andy Lutomirski and Borislav Petkov to > produce this. Andy provided the inspiration to add classes to the > exception table with a clever bit-squeezing trick, Boris pointed > out how much cleaner it would all be if we just had a new field. > > Linus Torvalds blessed the expansion with: > I'd rather not be clever in order to save just a tiny amount of space > in the exception table, which isn't really criticial for anybody. > > The third field is a simple integer indexing into an array of handler > functions (I thought it couldn't be a relative pointer like the other > fields because a module may have its ex_table loaded more than 2GB away > from the handler function - but that may not be actually true. But the > integer is pretty flexible, we are only really using low two bits now). > > We start out with three handlers: > > 0: Legacy - just jumps the to fixup IP > 1: Fault - provide the trap number in %ax to the fixup code > 2: Cleaned up legacy for the uaccess error hack I think I preferred the relative function pointer approach. Also, I think it would be nicer if the machine check code would invoke the handler regardless of which handler (or class) is selected. Then the handlers that don't want to handle #MC can just reject them. Also, can you make the handlers return bool instead of int? --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>