[PATCH v3 24/38] virtio_config: rewrite using _Generic

Michael S. Tsirkin
2020-08-05T17:16:39Z

Min compiler version has been raised, so that's ok now.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/virtio_config.h | 163 ++++++++++++++++------------------
1 file changed, 77 insertions(+), 86 deletions(-)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 5c3b02245ecd..7fa000f02721 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -288,112 +288,103 @@ static inline __virtio64 cpu_to_virtio64(struct virtio_device *vdev, u64 val)
return __cpu_to_virtio64(virtio_is_little_endian(vdev), val);
}

-/*
- * Only the checker differentiates between __virtioXX and __uXX types. But we
- * try to share as much code as we can with the regular GCC build.
- */
-#if !defined(CONFIG_CC_IS_GCC) && !defined(__CHECKER__)
+#define virtio_to_cpu(vdev, x) \
+ _Generic((x), \
+ __u8: (x), \
+ __virtio16: virtio16_to_cpu((vdev), (x)), \
+ __virtio32: virtio32_to_cpu((vdev), (x)), \
+ __virtio64: virtio64_to_cpu((vdev), (x)), \
+ /*
+ * Why define a default? checker can distinguish between
+ * e.g. __u16, __le16 and __virtio16, but GCC can't so
+ * attempts to define variants for both look like a duplicate
+ * variant to it.
+ */ \
+ default: _Generic((x), \
+ __u8: (x), \
+ __le16: virtio16_to_cpu((vdev), (__force __virtio16)(x)), \
+ __le32: virtio32_to_cpu((vdev), (__force __virtio32)(x)), \
+ __le64: virtio64_to_cpu((vdev), (__force __virtio64)(x)), \
+ default: _Generic((x), \
+ __u8: (x), \
+ __u16: virtio16_to_cpu((vdev), (__force __virtio16)(x)), \
+ __u32: virtio32_to_cpu((vdev), (__force __virtio32)(x)), \
+ __u64: virtio64_to_cpu((vdev), (__force __virtio64)(x)) \
+ ) \
+ ) \
+ )

-/* Not a checker - we can keep things simple */
-#define __virtio_native_typeof(x) typeof(x)
-
-#else
-
-/*
- * We build this out of a couple of helper macros in a vain attempt to
- * help you keep your lunch down while reading it.
- */
-#define __virtio_pick_value(x, type, then, otherwise) \
- __builtin_choose_expr(__same_type(x, type), then, otherwise)
-
-#define __virtio_pick_type(x, type, then, otherwise) \
- __virtio_pick_value(x, type, (then)0, otherwise)
-
-#define __virtio_pick_endian(x, x16, x32, x64, otherwise) \
- __virtio_pick_type(x, x16, __u16, \
- __virtio_pick_type(x, x32, __u32, \
- __virtio_pick_type(x, x64, __u64, \
- otherwise)))
-
-#define __virtio_native_typeof(x) typeof( \
- __virtio_pick_type(x, __u8, __u8, \
- __virtio_pick_endian(x, __virtio16, __virtio32, __virtio64, \
- __virtio_pick_endian(x, __le16, __le32, __le64, \
- /* No other type allowed */ \
- (void)0))))
-
-#endif
+#define cpu_to_virtio(vdev, x, m) \
+ _Generic((m), \
+ __u8: (x), \
+ __virtio16: cpu_to_virtio16((vdev), (x)), \
+ __virtio32: cpu_to_virtio32((vdev), (x)), \
+ __virtio64: cpu_to_virtio64((vdev), (x)), \
+ /*
+ * Why define a default? checker can distinguish between
+ * e.g. __u16, __le16 and __virtio16, but GCC can't so
+ * attempts to define variants for both look like a duplicate
+ * variant to it.
+ */ \
+ default: _Generic((m), \
+ __u8: (x), \
+ __le16: (__force __le16)cpu_to_virtio16((vdev), (x)), \
+ __le32: (__force __le32)cpu_to_virtio32((vdev), (x)), \
+ __le64: (__force __le64)cpu_to_virtio64((vdev), (x)), \
+ default: _Generic((m), \
+ __u8: (x), \
+ __u16: (__force __u16)cpu_to_virtio16((vdev), (x)), \
+ __u32: (__force __u32)cpu_to_virtio32((vdev), (x)), \
+ __u64: (__force __u64)cpu_to_virtio64((vdev), (x)) \
+ ) \
+ ) \
+ )

#define __virtio_native_type(structname, member) \
- __virtio_native_typeof(((structname*)0)->member)
-
-#define __virtio_typecheck(structname, member, val) \
- /* Must match the member's type, and be integer */ \
- typecheck(__virtio_native_type(structname, member), (val))
-
+ typeof(virtio_to_cpu(NULL, ((structname*)0)->member))

/* Config space accessors. */
#define virtio_cread(vdev, structname, member, ptr) \
do { \
- might_sleep(); \
- /* Must match the member's type, and be integer */ \
- if (!__virtio_typecheck(structname, member, *(ptr))) \
- (*ptr) = 1; \
+ typeof(((structname*)0)->member) virtio_cread_v; \
\
- switch (sizeof(*ptr)) { \
+ might_sleep(); \
+ /* Sanity check: must match the member's type */ \
+ typecheck(typeof(virtio_to_cpu((vdev), virtio_cread_v)), *(ptr)); \
+ \
+ switch (sizeof(virtio_cread_v)) { \
case 1: \
- *(ptr) = virtio_cread8(vdev, \
- offsetof(structname, member)); \
- break; \
case 2: \
- *(ptr) = virtio_cread16(vdev, \
- offsetof(structname, member)); \
- break; \
case 4: \
- *(ptr) = virtio_cread32(vdev, \
- offsetof(structname, member)); \
- break; \
- case 8: \
- *(ptr) = virtio_cread64(vdev, \
- offsetof(structname, member)); \
+ vdev->config->get((vdev), \
+ offsetof(structname, member), \
+ &virtio_cread_v, \
+ sizeof(virtio_cread_v)); \
break; \
default: \
- BUG(); \
+ __virtio_cread_many((vdev), \
+ offsetof(structname, member), \
+ &virtio_cread_v, \
+ 1, \
+ sizeof(virtio_cread_v)); \
+ break; \
} \
+ *(ptr) = virtio_to_cpu(vdev, virtio_cread_v); \
} while(0)

/* Config space accessors. */
#define virtio_cwrite(vdev, structname, member, ptr) \
do { \
- might_sleep(); \
- /* Must match the member's type, and be integer */ \
- if (!__virtio_typecheck(structname, member, *(ptr))) \
- BUG_ON((*ptr) == 1); \
+ typeof(((structname*)0)->member) virtio_cwrite_v = \
+ cpu_to_virtio(vdev, *(ptr), ((structname*)0)->member); \
\
- switch (sizeof(*ptr)) { \
- case 1: \
- virtio_cwrite8(vdev, \
- offsetof(structname, member), \
- *(ptr)); \
- break; \
- case 2: \
- virtio_cwrite16(vdev, \
- offsetof(structname, member), \
- *(ptr)); \
- break; \
- case 4: \
- virtio_cwrite32(vdev, \
- offsetof(structname, member), \
- *(ptr)); \
- break; \
- case 8: \
- virtio_cwrite64(vdev, \
- offsetof(structname, member), \
- *(ptr)); \
- break; \
- default: \
- BUG(); \
- } \
+ might_sleep(); \
+ /* Sanity check: must match the member's type */ \
+ typecheck(typeof(virtio_to_cpu((vdev), virtio_cwrite_v)), *(ptr)); \
+ \
+ vdev->config->set((vdev), offsetof(structname, member), \
+ &virtio_cwrite_v, \
+ sizeof(virtio_cwrite_v)); \
} while(0)

/* Read @count fields, @bytes each. */
--
MST