On Fri, Oct 24, 2014 at 1:19 PM, H. Peter Anvin <h...@zytor.com> wrote: > On 10/23/2014 12:38 PM, Eric Paris wrote: >>> >>> After the call __audit_syscall_entry aren't they already polluted? >>> Isn't that the reason we need to reload EAX? >> >> Well, I guess EAX is special... >> > > Because system calls are "asmlinkage", all the parameters are on the > stack, but %eax is used as the index into the system call table. This > should thus be fine until we get rid of regparm(0) entirely, if that > ever happens. >
...and because __audit_syscall_entry *isn't* asmlinkage, it uses the other convention, which is where the confusion comes from. And, by the time you get to sysenter_do_call, nothing cares about ecx, so you can freely clobber it while popping from the stack. I get it now. --Andy > -hpa > > -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
