On Thu, Dec 3, 2015 at 2:22 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote: > On Wed, Dec 2, 2015 at 5:13 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: >> Hi, >> >> On Thu, Dec 3, 2015 at 1:37 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >>> [resend as plain text] >>> >>> I want to bundle up an arbitrary ACPI_OBJECT into a copyable stream of >>> bytes, is there some standard way to do this? >>> >>> I'm asking because I want to try to upstream something resembling the >>> rusty old acpi_call module to allow users with debugfs access who are >>> willing to taint their kernel to evaluate ACPI objects from userspace. >>> Presumably there would be a user tool to get object info and to >>> evaluate methods, and we could handle translation to/from strings in >>> userspace, but I still need some way to shove the data back and forth. >> >> Please don't do that, this is broken as a concept. >> >> User space has no idea whatsoever about when and it what conditions a >> given AML can be executed in the first place, so in addition to >> tainting the kernel it may just outright break things. >> >> Not to mention the possibility of confusing the kernel's reference >> counting and breaking assumptions made by it on the current state of >> things based on what AML has been already executed. > > This is something that I want as a reader of decompiled DSDTs and a > writer of drivers. I think we could do it in a way that it doesn't > get used for evil. For example, make it a module, taint the kernel if > it's loaded and enabled, only expose the interface if an actual *boot* > parameter allow_user_acpi_calls=1 is set, encourage distros to > seriously consider not building the module, disallow it entirely under > secure boot, etc. > > I want to use it for things like "hey, it looks like \NEXP might have > a funny value -- let's see what's there without manually figuring out > how to peek at the relevant OpRegion". So please check the debugger thing. Lv, can you please help Andy with this? Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
