On Tue, Dec 05, 2017 at 05:06:31PM +0100, Arnd Bergmann wrote: > gcc-8 warns for every single definition of a system call entry > point, e.g.: > > include/linux/compat.h:56:18: error: 'compat_sys_rt_sigprocmask' alias between functions of incompatible types 'long int(int, compat_sigset_t *, compat_sigset_t *, compat_size_t)' {aka 'long int(int, struct <anonymous> *, struct <anonymous> *, unsigned int)'} and 'long int(long int, long int, long int, long int)' [-Werror=attribute-alias] > asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\ > ^~~~~~~~~~ > include/linux/compat.h:45:2: note: in expansion of macro 'COMPAT_SYSCALL_DEFINEx' > COMPAT_SYSCALL_DEFINEx(4, _##name, __VA_ARGS__) > ^~~~~~~~~~~~~~~~~~~~~~ > kernel/signal.c:2601:1: note: in expansion of macro 'COMPAT_SYSCALL_DEFINE4' > COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, > ^~~~~~~~~~~~~~~~~~~~~~ > include/linux/compat.h:60:18: note: aliased declaration here > asmlinkage long compat_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__))\ > ^~~~~~~~~~ > > The new warning seems reasonable in principle, but it doesn't > help us here, since we rely on the type mismatch to sanitize the > system call arguments. After I reported this as GCC PR82435, a new > -Wno-attribute-alias option was added that could be used to turn the > warning off globally on the command line, but I'd prefer to do it a > little more fine-grained. > > Interestingly, turning a warning off and on again inside of > a single macro doesn't always work, in this case I had to add > an extra statement inbetween and decided to copy the __SC_TEST > one from the native syscall to the compat syscall macro. See > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83256 for more details > about this. > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82435 > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Hi Arnd, What ever happened to this patch? I am compiline the kernel with the new OpenRISC GCC backend port https://github.com/stffrdhrn/gcc/commits/or1k-port, which is based on gcc 9.0.0 and seeing similar 'alias between functions of incompatible types' warnings. I found this old patch which seems will fix the issue, but it seems to not have been merged. Did we find another solution? Case in point, when I build x86 64 on gcc 8.1.1, I am not seeing the warnings. Is this not an issue for x86? -Stafford -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html