On Sat, Apr 17 2021 at 17:11, Andy Lutomirski wrote: > On Sat, Apr 17, 2021 at 4:53 PM Thomas Gleixner <t...@linutronix.de> wrote: >> which works for >> >> foo = function_nocfi(bar); > > I agree in general. But right now, we have, in asm/proto.h: > > void entry_SYSCALL_64(void); > > and that's pure nonsense. Depending on your point of view, > entry_SYSCALL_64 is a symbol that resolves to an integer or it's an > array of bytes containing instructions, but it is most definitely not > a function void (void). So, regardless of any CFI stuff, I propose > that we standardize our handling of prototypes of symbols that are > opaque to the C compiler. Here are a couple of choices: > > Easy one: > > extern u8 entry_SYSCALL_64[]; > > Slightly more complicated: > > struct opaque_symbol; > extern struct opaque_symbol entry_SYSCALL_64; > > The opaque_symbol variant avoids any possible confusion over the weird > status of arrays in C, and it's hard to misuse, since struct > opaque_symbol is an incomplete type.
Makes sense.
