atomic: Skip alignment check for try_cmpxchg() old arg

The 'old' argument in atomic_try_cmpxchg() and related functions is a
pointer to a normal non-atomic integer number, which does not require
to be naturally aligned, unlike the atomic_t/atomic64_t types themselves.

In order to add an alignment check with CONFIG_DEBUG_ATOMIC into the
normal instrument_atomic_read_write() helper, change this check to use
the non-atomic instrument_read_write(), the same way that was done
earlier for try_cmpxchg() in commit ec570320b09f ("locking/atomic:
Correct (cmp)xchg() instrumentation").

This prevents warnings on m68k calling the 32-bit atomic_try_cmpxchg()
with 16-bit aligned arguments as well as several more architectures
including x86-32 when calling atomic64_try_cmpxchg() with 32-bit
aligned u64 arguments.

Reported-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/cover.1757810729.git.fthain@linux-m68k.org/

diff --git a/include/linux/atomic/atomic-instrumented.h b/include/linux/atomic/atomic-instrumented.h
index 9409a6ddf3e0df7bff691ad790074ea53ea06bb5..37ab6314a9f766301c36f86213d632b22ac72b13 100644 (file)
--- a/include/linux/atomic/atomic-instrumented.h
+++ b/include/linux/atomic/atomic-instrumented.h
@@ -1276,7 +1276,7 @@ atomic_try_cmpxchg(atomic_t *v, int *old, int new)
 {
        kcsan_mb();
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_try_cmpxchg(v, old, new);
 }
 
@@ -1298,7 +1298,7 @@ static __always_inline bool
 atomic_try_cmpxchg_acquire(atomic_t *v, int *old, int new)
 {
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_try_cmpxchg_acquire(v, old, new);
 }
 
@@ -1321,7 +1321,7 @@ atomic_try_cmpxchg_release(atomic_t *v, int *old, int new)
 {
        kcsan_release();
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_try_cmpxchg_release(v, old, new);
 }
 
@@ -1343,7 +1343,7 @@ static __always_inline bool
 atomic_try_cmpxchg_relaxed(atomic_t *v, int *old, int new)
 {
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_try_cmpxchg_relaxed(v, old, new);
 }
 
@@ -2854,7 +2854,7 @@ atomic64_try_cmpxchg(atomic64_t *v, s64 *old, s64 new)
 {
        kcsan_mb();
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic64_try_cmpxchg(v, old, new);
 }
 
@@ -2876,7 +2876,7 @@ static __always_inline bool
 atomic64_try_cmpxchg_acquire(atomic64_t *v, s64 *old, s64 new)
 {
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic64_try_cmpxchg_acquire(v, old, new);
 }
 
@@ -2899,7 +2899,7 @@ atomic64_try_cmpxchg_release(atomic64_t *v, s64 *old, s64 new)
 {
        kcsan_release();
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic64_try_cmpxchg_release(v, old, new);
 }
 
@@ -2921,7 +2921,7 @@ static __always_inline bool
 atomic64_try_cmpxchg_relaxed(atomic64_t *v, s64 *old, s64 new)
 {
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic64_try_cmpxchg_relaxed(v, old, new);
 }
 
@@ -4432,7 +4432,7 @@ atomic_long_try_cmpxchg(atomic_long_t *v, long *old, long new)
 {
        kcsan_mb();
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_long_try_cmpxchg(v, old, new);
 }
 
@@ -4454,7 +4454,7 @@ static __always_inline bool
 atomic_long_try_cmpxchg_acquire(atomic_long_t *v, long *old, long new)
 {
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_long_try_cmpxchg_acquire(v, old, new);
 }
 
@@ -4477,7 +4477,7 @@ atomic_long_try_cmpxchg_release(atomic_long_t *v, long *old, long new)
 {
        kcsan_release();
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_long_try_cmpxchg_release(v, old, new);
 }
 
@@ -4499,7 +4499,7 @@ static __always_inline bool
 atomic_long_try_cmpxchg_relaxed(atomic_long_t *v, long *old, long new)
 {
        instrument_atomic_read_write(v, sizeof(*v));
-       instrument_atomic_read_write(old, sizeof(*old));
+       instrument_read_write(old, sizeof(*old));
        return raw_atomic_long_try_cmpxchg_relaxed(v, old, new);
 }
 
@@ -5050,4 +5050,4 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 
 
 #endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
-// 8829b337928e9508259079d32581775ececd415b
+// f618ac667f868941a84ce0ab2242f1786e049ed4

diff --git a/scripts/atomic/gen-atomic-instrumented.sh b/scripts/atomic/gen-atomic-instrumented.sh
index 592f3ec89b5f178046eaca8873b7c91ec6f6c300..9c1d53f81eb2cbc7993243fbbab16cc68db5b1d0 100755 (executable)
--- a/scripts/atomic/gen-atomic-instrumented.sh
+++ b/scripts/atomic/gen-atomic-instrumented.sh
@@ -12,7 +12,7 @@ gen_param_check()
        local arg="$1"; shift
        local type="${arg%%:*}"
        local name="$(gen_param_name "${arg}")"
-       local rw="write"
+       local rw="atomic_write"
 
        case "${type#c}" in
        i) return;;
@@ -20,14 +20,17 @@ gen_param_check()
 
        if [ ${type#c} != ${type} ]; then
                # We don't write to constant parameters.
-               rw="read"
+               rw="atomic_read"
+       elif [ "${type}" = "p" ] ; then
+               # The "old" argument in try_cmpxchg() gets accessed non-atomically
+               rw="read_write"
        elif [ "${meta}" != "s" ]; then
                # An atomic RMW: if this parameter is not a constant, and this atomic is
                # not just a 's'tore, this parameter is both read from and written to.
-               rw="read_write"
+               rw="atomic_read_write"
        fi
 
-       printf "\tinstrument_atomic_${rw}(${name}, sizeof(*${name}));\n"
+       printf "\tinstrument_${rw}(${name}, sizeof(*${name}));\n"
 }
 
 #gen_params_checks(meta, arg...)