Re: [PATCH] uapi: Make __{u,s}64 match {u,}int64_t in userspace

Hi!

quoted

+#include <asm/bitsperlong.h>
+
 /*
- * int-ll64 is used everywhere now.
+ * int-ll64 is used everywhere in kernel now.
  */
-#include <asm-generic/int-ll64.h>
+#if __BITS_PER_LONG == 64 && !defined(__KERNEL__)
+# include <asm-generic/int-l64.h>
+#else
+# include <asm-generic/int-ll64.h>
+#endif

I don't think this is correct on all 64-bit architectures, as far as I
remember the
definition can use either 'long' or 'long long' depending on the user space
toolchain.

As far as I can tell the userspace bits/types.h does exactly the same
check in order to define uint64_t and int64_t, i.e.:

#if __WORDSIZE == 64
typedef signed long int __int64_t;
typedef unsigned long int __uint64_t;
#else
__extension__ typedef signed long long int __int64_t;
__extension__ typedef unsigned long long int __uint64_t;
#endif

The macro __WORDSIZE is defined per architecture, and it looks like the
defintions in glibc sources in bits/wordsize.h match the uapi
asm/bitsperlong.h. But I may have missed something, the code in glibc is
not exactly easy to read.

Out of the ten supported 64-bit architectures, there are four that already
use asm-generic/int-l64.h conditionally, and six that don't, and I
think at least
some of those are intentional.

I think it would be safer to do this one architecture at a time to make
sure this doesn't regress on those that require the int-ll64.h version.

I'm still trying to understand what exactly can go wrong here. As long
as __BITS_PER_LONG is correctly defined the __u64 and __s64 will be
correctly sized as well. The only visible change is that one 'long' is
dropped from the type when it's not needed.

There should also be a check for __SANE_USERSPACE_TYPES__
to let userspace ask for the ll64 version everywhere.

That one is easy to fix at least.

-- 
Cyril Hrubis
chrubis@suse.cz