From d12157efc8e083c77d054675fcdd594f54cc7e2b Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@arm.com>
Date: Mon, 5 Jun 2023 08:01:01 +0100
Subject: locking/atomic: make atomic*_{cmp,}xchg optional

Most architectures define the atomic/atomic64 xchg and cmpxchg
operations in terms of arch_xchg and arch_cmpxchg respectfully.

Add fallbacks for these cases and remove the trivial cases from arch
code. On some architectures the existing definitions are kept as these
are used to build other arch_atomic*() operations.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-5-mark.rutland@arm.com
---
 scripts/atomic/fallbacks/cmpxchg | 7 +++++++
 scripts/atomic/fallbacks/xchg    | 7 +++++++
 2 files changed, 14 insertions(+)
 create mode 100644 scripts/atomic/fallbacks/cmpxchg
 create mode 100644 scripts/atomic/fallbacks/xchg

(limited to 'scripts')

diff --git a/scripts/atomic/fallbacks/cmpxchg b/scripts/atomic/fallbacks/cmpxchg
new file mode 100644
index 000000000000..87cd010f98d5
--- /dev/null
+++ b/scripts/atomic/fallbacks/cmpxchg
@@ -0,0 +1,7 @@
+cat <<EOF
+static __always_inline ${int}
+arch_${atomic}_cmpxchg${order}(${atomic}_t *v, ${int} old, ${int} new)
+{
+	return arch_cmpxchg${order}(&v->counter, old, new);
+}
+EOF
diff --git a/scripts/atomic/fallbacks/xchg b/scripts/atomic/fallbacks/xchg
new file mode 100644
index 000000000000..733b8980b2f3
--- /dev/null
+++ b/scripts/atomic/fallbacks/xchg
@@ -0,0 +1,7 @@
+cat <<EOF
+static __always_inline ${int}
+arch_${atomic}_xchg${order}(${atomic}_t *v, ${int} new)
+{
+	return arch_xchg${order}(&v->counter, new);
+}
+EOF
-- 
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