Add a new Coccinelle script which replaces uses of the inplace
byteswapping functions *_to_cpus() and cpu_to_*s() with their
not-in-place equivalents. This is useful for where the swapping
is done on members of a packed struct -- taking the address
of the member to pass it to an inplace function is undefined
behaviour in C.
Signed-off-by: Peter Maydell <address@hidden>
---
Richard asked for a coccinelle script in the scripts/coccinelle
directory, so here's a patch to add it.
scripts/coccinelle/inplace-byteswaps.cocci | 65 ++++++++++++++++++++++
1 file changed, 65 insertions(+)
create mode 100644 scripts/coccinelle/inplace-byteswaps.cocci
diff --git a/scripts/coccinelle/inplace-byteswaps.cocci
b/scripts/coccinelle/inplace-byteswaps.cocci
new file mode 100644
index 00000000000..a869a90cbfd
--- /dev/null
+++ b/scripts/coccinelle/inplace-byteswaps.cocci
@@ -0,0 +1,65 @@
+// Replace uses of in-place byteswapping functions with calls to the
+// equivalent not-in-place functions. This is necessary to avoid
+// undefined behaviour if the expression being swapped is a field in a
+// packed struct.
+
+@@
+expression E;
+@@
+-be16_to_cpus(&E);
++E = be16_to_cpu(E);
+@@
+expression E;
+@@
+-be32_to_cpus(&E);
++E = be32_to_cpu(E);