kernel: Fix compilation for non-gki kernels (#593)

kernel/kernel_compat.c

@@ -78,57 +78,3 @@ long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
     return ret;
 }
 #endif
-
-long ksu_strncpy_from_user_retry(char *dst, const void __user *unsafe_addr,
-                   long count)
-{
-    long ret;
-
-    ret = ksu_strncpy_from_user_nofault(dst, unsafe_addr, count);
-    if (likely(ret >= 0))
-        return ret;
-
-    // we faulted! fallback to slow path
-    if (unlikely(!ksu_access_ok(unsafe_addr, count))) {
-#ifdef CONFIG_KSU_DEBUG
-        pr_err("%s: faulted!\n", __func__);
-#endif
-        return -EFAULT;
-    }
-
-    // why we don't do like how strncpy_from_user_nofault?
-    ret = strncpy_from_user(dst, unsafe_addr, count);
-
-    if (ret >= count) {
-        ret = count;
-        dst[ret - 1] = '\0';
-    } else if (likely(ret >= 0)) {
-        ret++;
-    }
-
-    return ret;
-}
-
-long ksu_copy_from_user_nofault(void *dst, const void __user *src, size_t size)
-{
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)
-    return copy_from_user_nofault(dst, src, size);
-#else
-    // https://elixir.bootlin.com/linux/v5.8/source/mm/maccess.c#L205
-    long ret = -EFAULT;
-    mm_segment_t old_fs = get_fs();
-
-    set_fs(USER_DS);
-    // tweaked to use ksu_access_ok
-    if (ksu_access_ok(src, size)) {
-        pagefault_disable();
-        ret = __copy_from_user_inatomic(dst, src, size);
-        pagefault_enable();
-    }
-    set_fs(old_fs);
-
-    if (ret)
-        return -EFAULT;
-    return 0;
-#endif
-}