On Fri, Aug 19, 2011 at 11:49:50AM +0800, Yong Zhang wrote:
> Cc'ing more people.
>
> On Thu, Aug 18, 2011 at 09:19:11PM +0100, Ralf Baechle wrote:
> > > But really I think this patch fixes things at the wrong level. Each
> > > architecture potentially needs a similar patch. What would happen if
> > > we did something like:
> >
> > > +++ b/kernel/futex_compat.c
> > > @@ -180,9 +180,9 @@ err_unlock:
> > > return ret;
> > > }
> > >
> > > -asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
> > > - struct compat_timespec __user *utime, u32 __user *uaddr2,
> > > - u32 val3)
> > > +SYSCALL_DEFINE6(compat_sys_futex, u32 __user *, uaddr, int , op, u32, val,
> > > + struct compat_timespec __user *, utime, u32 __user *, uaddr2,
> > > + u32, val3)
> > > {
> > > struct timespec ts;
> > > ktime_t t, *tp = NULL;
> > >
> > > Obviously the function name is wrong, but a varient of
> > > SYSCALL_DEFINE*() could be created so the proper function names are
> > > produced.
> >
> > Right now none of the the generic compat_ functions is wrapped in
> > SYSCALL_DEFINE* because for some architectures a further wrapper function
> > is needed. It seems some architectures call compat_ calls directly
> > without SYSCALL_DEFINE* which with CONFIG_FTRACE_SYSCALLS is a bug ...
>
> Just checked some archs which have HAVE_SYSCALL_TRACEPOINTS=y and could
> call compat_* syscalls when run 32bit process on 64bit kernel, I don't
> find any special code against FTRACE_SYSCALLS. So that means we could
> not trace compat syscalls even if we want to(Am I missing something?).
> So I think if we want to trace it, the easy way is just like what we have
> done on normal syscalls, IOW, we could SYSCALL_DEFINE all of the compat
> syscalls.
Except the ones which call sys_* finally, :)
>
> Thought?
>
> BTW, I have make a trival patch to introduce COMPAT_SYSCALL_DEFINE, it's just
> for calling of inspiration(no test no build, and I leave SYSCALL_METADATA
> etc untouched.)
>
> Thanks,
> Yong
>
> ---
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 8c03b98..e79027f 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -221,26 +221,38 @@ extern struct trace_event_functions exit_syscall_print_funcs;
> __SC_STR_ADECL##x(__VA_ARGS__) \
> }; \
> SYSCALL_METADATA(sname, x); \
> - __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
> + __SYSCALL_DEFINEx(, x, sname, __VA_ARGS__)
> +
> +#define COMPAT_SYSCALL_DEFINEx(x, sname, ...) \
> + static const char *types_compat_##sname[] = { \
> + __SC_STR_TDECL##x(__VA_ARGS__) \
> + }; \
> + static const char *args_compat_##sname[] = { \
> + __SC_STR_ADECL##x(__VA_ARGS__) \
> + }; \
> + SYSCALL_METADATA(compat, sname, x); \
> + __SYSCALL_DEFINEx(cmopat_, x, sname, __VA_ARGS__)
> #else
> #define SYSCALL_DEFINEx(x, sname, ...) \
> - __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
> + __SYSCALL_DEFINEx(, x, sname, __VA_ARGS__)
> +#define COMPAT_SYSCALL_DEFINEx(x, sname, ...) \
> + __SYSCALL_DEFINEx(compat_, x, sname, __VA_ARGS__)
> #endif
>
> #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
>
> -#define SYSCALL_DEFINE(name) static inline long SYSC_##name
> +#define SYSCALL_DEFINE(compat, name) static inline long compat##SYSC_##name
>
> -#define __SYSCALL_DEFINEx(x, name, ...) \
> - asmlinkage long sys##name(__SC_DECL##x(__VA_ARGS__)); \
> - static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__)); \
> - asmlinkage long SyS##name(__SC_LONG##x(__VA_ARGS__)) \
> +#define __SYSCALL_DEFINEx(compat, x, name, ...) \
> + asmlinkage long compat##sys##name(__SC_DECL##x(__VA_ARGS__)); \
> + static inline long compat##SYSC##name(__SC_DECL##x(__VA_ARGS__));\
> + asmlinkage long compat##SyS##name(__SC_LONG##x(__VA_ARGS__)) \
> { \
> __SC_TEST##x(__VA_ARGS__); \
> - return (long) SYSC##name(__SC_CAST##x(__VA_ARGS__)); \
> + return (long) compat##SYSC##name(__SC_CAST##x(__VA_ARGS__));\
> } \
> - SYSCALL_ALIAS(sys##name, SyS##name); \
> - static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__))
> + SYSCALL_ALIAS(compat##sys##name, compat##SyS##name); \
> + static inline long compat##SYSC##name(__SC_DECL##x(__VA_ARGS__))
>
> #else /* CONFIG_HAVE_SYSCALL_WRAPPERS */
>
