On Tue, 30 Aug 2016 11:52:39 -0700 Andy Lutomirski <l...@amacapital.net> wrote:
> Okay, I think I see what's going on. init_ftrace_syscalls() does: > > meta = find_syscall_meta(addr); > > Unless I'm missing some reason why this is a sensible thing to do, > this seems overcomplicated and incorrect. There is exactly one caller > of find_syscall_meta() and that caller knows the syscall number. Why > doesn't it just look up the metadata by *number* instead of by syscall > implementation address? There are plenty of architectures for which > multiple logically different syscalls can share an implementation > (e.g. pretty much everything that calls in_compat_syscall()). The problem is that the meta data is created at the syscalls themselves. Look at all the macro magic in include/linux/syscalls.h, and search for __syscall_metadata. The meta data is created via linker magic, and the find_syscall_meta() is what finds a specific system call and the meta data associated with it. Then it can use the number to system call mapping. Yes, this code needs some loving. -- Steve
