[xen master] tools: add access macros for unaligned data

[patchbot@xxxxxxx]

commit 40da8a7e4b94e4925bbc259e206d7f8690486263
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Wed Feb 14 10:41:59 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Feb 14 10:41:59 2024 +0100

    tools: add access macros for unaligned data
    
    Add the basic access macros for unaligned data to common-macros.h.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/include/xen-tools/common-macros.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tools/include/xen-tools/common-macros.h 
b/tools/include/xen-tools/common-macros.h
index e5ed603904..81fba2e9f5 100644
--- a/tools/include/xen-tools/common-macros.h
+++ b/tools/include/xen-tools/common-macros.h
@@ -79,6 +79,10 @@
 #define __must_check __attribute__((__warn_unused_result__))
 #endif
 
+#ifndef __packed
+#define __packed __attribute__((__packed__))
+#endif
+
 #define container_of(ptr, type, member) ({              \
     typeof(((type *)0)->member) *mptr__ = (ptr);        \
     (type *)((char *)mptr__ - offsetof(type, member));  \
@@ -87,4 +91,17 @@
 #define __AC(X, Y)   (X ## Y)
 #define _AC(X, Y)    __AC(X, Y)
 
+#define get_unaligned_t(type, ptr) ({                               \
+    const struct { type x; } __packed *ptr_ = (typeof(ptr_))(ptr);  \
+    ptr_->x;                                                        \
+})
+
+#define put_unaligned_t(type, val, ptr) do {                        \
+    struct { type x; } __packed *ptr_ = (typeof(ptr_))(ptr);        \
+    ptr_->x = val;                                                  \
+} while (0)
+
+#define get_unaligned(ptr)      get_unaligned_t(typeof(*(ptr)), ptr)
+#define put_unaligned(val, ptr) put_unaligned_t(typeof(*(ptr)), val, ptr)
+
 #endif /* __XEN_TOOLS_COMMON_MACROS__ */
--
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