On Fri, Jan 8, 2016 at 11:29 AM, Luck, Tony <tony.luck@xxxxxxxxx> wrote: >>> +EXPORT_SYMBOL(ex_handler_default); >> >> Why not EXPORT_SYMBOL_GPL() ? >> >> We do not care about external modules. > > I thought the guideline was that new features are GPL, but changes > to existing features shouldn't break by adding new GPL requirements. > > The point is moot though because the shared hallucinations wore > off this morning and I realized that having the "handler" be a pointer > to a function can't work. We're storing the 32-bit signed offset from > the extable to the target address. This is fine if the table and the > address are close together. But for modules we have an exception > table wherever vmalloc() loaded the module, and a function back > in the base kernel. > > So back to your ".long 0" for the default case. And if we want to allow > modules to use any of the new handlers, then we can't use > relative function pointers for them either. > > So I'm looking at making the new field just a simple integer and using > it to index an array of function pointers (like in v7). > > Unless someone has a better idea? Aren't modules loaded in the top 2GB of address space like the main kernel? Otherwise rip-relative addressing wouldn't work and modules would have to be compiled as PIC. -- Brian Gerst -- 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>