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From:   Mark Rutland <mark.rutland@arm.com>
To:     linux-kernel@vger.kernel.org
Cc:     boqun.feng@gmail.com, elver@google.com, mark.rutland@arm.com,
        peterz@infradead.org, will@kernel.org
Subject: [PATCH] locking/atomic: correct (cmp)xhcg instrumentation
Date:   Thu, 13 Apr 2023 17:06:44 +0100
Message-Id: <20230413160644.490976-1-mark.rutland@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

All xchg() and cmpxchg() ops are atomic RMWs, but currently we
instrument these with instrument_atomic_write() rather than
instrument_atomic_read_write(), missing the read aspect.

Similarly, all try_cmpxchg() ops are non-atomic RMWs on *oldp, but we
instrument these accesses with instrument_atomic_write() rather than
instrument_read_write(), missing the read aspect and erroneously marking
these as atomic.

Fix the instrumentation for both points.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
---
 include/linux/atomic/atomic-instrumented.h | 76 +++++++++++-----------
 scripts/atomic/gen-atomic-instrumented.sh  |  6 +-
 2 files changed, 41 insertions(+), 41 deletions(-)

Note: this is based on tip locking/core, with the head commit being:

  561b081f19655a46 ("locking/x86: Define arch_try_cmpxchg_local")

Mark.

diff --git a/include/linux/atomic/atomic-instrumented.h b/include/linux/atomic/atomic-instrumented.h
index 245ba661c4938..03a232a1fa578 100644
--- a/include/linux/atomic/atomic-instrumented.h
+++ b/include/linux/atomic/atomic-instrumented.h
@@ -1948,14 +1948,14 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_xchg(__ai_ptr, __VA_ARGS__); \
 })
 
 #define xchg_acquire(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_xchg_acquire(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -1963,14 +1963,14 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_release(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_xchg_release(__ai_ptr, __VA_ARGS__); \
 })
 
 #define xchg_relaxed(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_xchg_relaxed(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -1978,14 +1978,14 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg(__ai_ptr, __VA_ARGS__); \
 })
 
 #define cmpxchg_acquire(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg_acquire(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -1993,14 +1993,14 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_release(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg_release(__ai_ptr, __VA_ARGS__); \
 })
 
 #define cmpxchg_relaxed(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg_relaxed(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -2008,14 +2008,14 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg64(__ai_ptr, __VA_ARGS__); \
 })
 
 #define cmpxchg64_acquire(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg64_acquire(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -2023,14 +2023,14 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_release(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg64_release(__ai_ptr, __VA_ARGS__); \
 })
 
 #define cmpxchg64_relaxed(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg64_relaxed(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -2039,8 +2039,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2048,8 +2048,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg_acquire(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2058,8 +2058,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
 	kcsan_release(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg_release(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2067,8 +2067,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg_relaxed(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2077,8 +2077,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg64(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2086,8 +2086,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg64_acquire(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2096,8 +2096,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
 	kcsan_release(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg64_release(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2105,22 +2105,22 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg64_relaxed(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
 #define cmpxchg_local(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg_local(__ai_ptr, __VA_ARGS__); \
 })
 
 #define cmpxchg64_local(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_cmpxchg64_local(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -2128,7 +2128,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
 	arch_sync_cmpxchg(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -2136,8 +2136,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg_local(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2145,8 +2145,8 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	typeof(oldp) __ai_oldp = (oldp); \
-	instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
-	instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+	instrument_atomic_read_write(__ai_ptr, sizeof(*__ai_ptr)); \
+	instrument_read_write(__ai_oldp, sizeof(*__ai_oldp)); \
 	arch_try_cmpxchg64_local(__ai_ptr, __ai_oldp, __VA_ARGS__); \
 })
 
@@ -2154,7 +2154,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
 	kcsan_mb(); \
-	instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
 	arch_cmpxchg_double(__ai_ptr, __VA_ARGS__); \
 })
 
@@ -2162,9 +2162,9 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 #define cmpxchg_double_local(ptr, ...) \
 ({ \
 	typeof(ptr) __ai_ptr = (ptr); \
-	instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
+	instrument_atomic_read_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
 	arch_cmpxchg_double_local(__ai_ptr, __VA_ARGS__); \
 })
 
 #endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
-// 97fe4d79aa058d2164df824632cbc4f716d2a407
+// 6b513a42e1a1b5962532a019b7fc91eaa044ad5e
diff --git a/scripts/atomic/gen-atomic-instrumented.sh b/scripts/atomic/gen-atomic-instrumented.sh
index c8165e9431bf8..d9ffd74f73ca2 100755
--- a/scripts/atomic/gen-atomic-instrumented.sh
+++ b/scripts/atomic/gen-atomic-instrumented.sh
@@ -104,8 +104,8 @@ cat <<EOF
 EOF
 [ -n "$kcsan_barrier" ] && printf "\t${kcsan_barrier}; \\\\\n"
 cat <<EOF
-	instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
-	instrument_atomic_write(__ai_oldp, ${mult}sizeof(*__ai_oldp)); \\
+	instrument_atomic_read_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
+	instrument_read_write(__ai_oldp, ${mult}sizeof(*__ai_oldp)); \\
 	arch_${xchg}${order}(__ai_ptr, __ai_oldp, __VA_ARGS__); \\
 })
 EOF
@@ -119,7 +119,7 @@ cat <<EOF
 EOF
 [ -n "$kcsan_barrier" ] && printf "\t${kcsan_barrier}; \\\\\n"
 cat <<EOF
-	instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
+	instrument_atomic_read_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
 	arch_${xchg}${order}(__ai_ptr, __VA_ARGS__); \\
 })
 EOF
-- 
2.30.2