Hi, We're working on adding x32 support in musl libc, and ran into a pretty major obstacle that the glibc folks seem to have glossed over: when the kernel reads timespec structures from x32 userspace, it treats both tv_sec and tv_nsec as 64-bit values. This requires userspace either to be non-conforming to ISO C11 and POSIX (both of which require tv_nsec to have type long, not an implementation-defined signed integer type) or to wrap syscalls with ugly x32-specific wrappers to copy the input timespec to a temporary location where it can be sign-extended to 64-bit for passing to the kernel. glibc has (so far) taken the former approach, documented in this bug report: https://sourceware.org/bugzilla/show_bug.cgi?id=16437 I'd like to see this fixed on the kernel side by having kernel/compat.c modified to copy tv_sec and tv_nsec copied separately as 64-bit and 32-bit values, respectively, rather than using copy_from_user for the whole structure, when COMPAT_USE_64BIT_TIME is true. Note that copy_to_user still works for writing timespec results back to userspace; the excess data just goes into padding bits, and it's always necessarily zero because output tv_nsec values are never outside the range [0,999999999]. Rich -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
