lkl: Fix up libhijack stat ABI

We are hijacking `stat`, where the size of the target struct is
dependent on the wordsize. Delegating to `__xstat64` is incorrect, as it
unconditionally uses the stat64 layout and will result in an out-of-bounds
write on 32-bit architectures.

Additionally, the specification claims that the version must be specified
as 3 or the behavior is undefined. This only seems to affect 32-bit
architectures, as 64-bit architectures require version 1 to produce
correct outputs when `__xstat` is called.

Fixes: d4b9b65 ("lkl: update dpdk version to 17.02 from 2.2")
Signed-off-by: Tim Schumacher <[email protected]>

Author: timschumi

tools/lkl/lib/hijack/hijack.c

@@ -587,11 +587,15 @@ void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
 }
 
 #ifndef __ANDROID__
-HOST_CALL(__xstat64)
+HOST_CALL(__xstat)
 int stat(const char *pathname, struct stat *buf)
 {
-	CHECK_HOST_CALL(__xstat64);
-	return host___xstat64(0, pathname, buf);
+	CHECK_HOST_CALL(__xstat);
+#if defined(LKL_CONFIG_64BIT)
+	return host___xstat(1, pathname, buf);
+#else
+	return host___xstat(3, pathname, buf);
+#endif
 }
 #endif