From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Cc: patches@linaro.org, Richard Henderson <richard.henderson@linaro.org>
Subject: [Qemu-devel] [PATCH] coccinelle: new inplace-byteswaps.cocci to remove inplace-byteswapping calls
Date: Tue, 9 Oct 2018 19:16:12 +0100 [thread overview]
Message-ID: <20181009181612.10633-1-peter.maydell@linaro.org> (raw)
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 <peter.maydell@linaro.org>
---
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);
+@@
+expression E;
+@@
+-be64_to_cpus(&E);
++E = be64_to_cpu(E);
+@@
+expression E;
+@@
+-cpu_to_be16s(&E);
++E = cpu_to_be16(E);
+@@
+expression E;
+@@
+-cpu_to_be32s(&E);
++E = cpu_to_be32(E);
+@@
+expression E;
+@@
+-cpu_to_be64s(&E);
++E = cpu_to_be64(E);
+@@
+expression E;
+@@
+-le16_to_cpus(&E);
++E = le16_to_cpu(E);
+@@
+expression E;
+@@
+-le32_to_cpus(&E);
++E = le32_to_cpu(E);
+@@
+expression E;
+@@
+-le64_to_cpus(&E);
++E = le64_to_cpu(E);
+@@
+expression E;
+@@
+-cpu_to_le16s(&E);
++E = cpu_to_le16(E);
+@@
+expression E;
+@@
+-cpu_to_le32s(&E);
++E = cpu_to_le32(E);
+@@
+expression E;
+@@
+-cpu_to_le64s(&E);
++E = cpu_to_le64(E);
--
2.19.0
next reply other threads:[~2018-10-09 18:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-09 18:16 Peter Maydell [this message]
2018-10-09 18:23 ` [Qemu-devel] [PATCH] coccinelle: new inplace-byteswaps.cocci to remove inplace-byteswapping calls Eric Blake
2018-10-09 18:35 ` Peter Maydell
2018-10-10 9:01 ` Philippe Mathieu-Daudé
2018-10-10 14:26 ` Richard Henderson
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