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From:   Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Boqun Feng <boqun.feng@gmail.com>,
        "H . Peter Anvin" <hpa@zytor.com>, Paul Turner <pjt@google.com>,
        linux-api@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
        linux-kselftest@vger.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: [PATCH 4/4] selftests/rseq: Use rseq_unqual_scalar_typeof in macros
Date:   Mon, 15 May 2023 09:58:01 -0400
Message-Id: <20230515135801.15220-5-mathieu.desnoyers@efficios.com>
In-Reply-To: <20230515135801.15220-1-mathieu.desnoyers@efficios.com>
References: <20230515135801.15220-1-mathieu.desnoyers@efficios.com>
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Use rseq_unqual_scalar_typeof() rather than typeof() in macros to remove
the volatile qualifier (if there is one in the input argument), thus
generating better assembly code in those scenarios.

Also add extra brackets around the "p" parameter in RSEQ_READ_ONCE(),
RSEQ_WRITE_ONCE(), and rseq_unqual_scalar_typeof() across architectures
to preserve expectations of operator priority. Here is an example that
shows how operator priority may be an issue with missing parentheses:

    #define m(p) \
    do { \
            __typeof__(*p) v = 0; \
    } while (0)

    void fct(unsigned long long *p1)
    {
            m(p1 + 1);      /* works */
            m(1 + p1);      /* broken */
    }

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 tools/testing/selftests/rseq/rseq-arm.h   | 4 ++--
 tools/testing/selftests/rseq/rseq-mips.h  | 4 ++--
 tools/testing/selftests/rseq/rseq-ppc.h   | 4 ++--
 tools/testing/selftests/rseq/rseq-riscv.h | 6 +++---
 tools/testing/selftests/rseq/rseq-s390.h  | 4 ++--
 tools/testing/selftests/rseq/rseq-x86.h   | 4 ++--
 6 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/rseq/rseq-arm.h b/tools/testing/selftests/rseq/rseq-arm.h
index 8414fc3eac15..d887b3bbe257 100644
--- a/tools/testing/selftests/rseq/rseq-arm.h
+++ b/tools/testing/selftests/rseq/rseq-arm.h
@@ -66,7 +66,7 @@
 
 #define rseq_smp_load_acquire(p)					\
 __extension__ ({							\
-	__typeof(*p) ____p1 = RSEQ_READ_ONCE(*p);			\
+	rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));	\
 	rseq_smp_mb();							\
 	____p1;								\
 })
@@ -76,7 +76,7 @@ __extension__ ({							\
 #define rseq_smp_store_release(p, v)					\
 do {									\
 	rseq_smp_mb();							\
-	RSEQ_WRITE_ONCE(*p, v);						\
+	RSEQ_WRITE_ONCE(*(p), v);					\
 } while (0)
 
 #define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip,	\
diff --git a/tools/testing/selftests/rseq/rseq-mips.h b/tools/testing/selftests/rseq/rseq-mips.h
index 50b950cf9585..42ef8e946693 100644
--- a/tools/testing/selftests/rseq/rseq-mips.h
+++ b/tools/testing/selftests/rseq/rseq-mips.h
@@ -45,7 +45,7 @@
 
 #define rseq_smp_load_acquire(p)					\
 __extension__ ({							\
-	__typeof(*p) ____p1 = RSEQ_READ_ONCE(*p);			\
+	rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));	\
 	rseq_smp_mb();							\
 	____p1;								\
 })
@@ -55,7 +55,7 @@ __extension__ ({							\
 #define rseq_smp_store_release(p, v)					\
 do {									\
 	rseq_smp_mb();							\
-	RSEQ_WRITE_ONCE(*p, v);						\
+	RSEQ_WRITE_ONCE(*(p), v);					\
 } while (0)
 
 #if _MIPS_SZLONG == 64
diff --git a/tools/testing/selftests/rseq/rseq-ppc.h b/tools/testing/selftests/rseq/rseq-ppc.h
index dc9190facee9..57b160597189 100644
--- a/tools/testing/selftests/rseq/rseq-ppc.h
+++ b/tools/testing/selftests/rseq/rseq-ppc.h
@@ -23,7 +23,7 @@
 
 #define rseq_smp_load_acquire(p)					\
 __extension__ ({							\
-	__typeof(*p) ____p1 = RSEQ_READ_ONCE(*p);			\
+	rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));	\
 	rseq_smp_lwsync();						\
 	____p1;								\
 })
@@ -33,7 +33,7 @@ __extension__ ({							\
 #define rseq_smp_store_release(p, v)					\
 do {									\
 	rseq_smp_lwsync();						\
-	RSEQ_WRITE_ONCE(*p, v);						\
+	RSEQ_WRITE_ONCE(*(p), v);					\
 } while (0)
 
 /*
diff --git a/tools/testing/selftests/rseq/rseq-riscv.h b/tools/testing/selftests/rseq/rseq-riscv.h
index 17932a79e066..37e598d0a365 100644
--- a/tools/testing/selftests/rseq/rseq-riscv.h
+++ b/tools/testing/selftests/rseq/rseq-riscv.h
@@ -36,8 +36,8 @@
 
 #define rseq_smp_load_acquire(p)					\
 __extension__ ({							\
-	__typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));			\
-	RISCV_FENCE(r, rw)						\
+	rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));	\
+	RISCV_FENCE(r, rw);						\
 	____p1;								\
 })
 
@@ -46,7 +46,7 @@ __extension__ ({							\
 #define rseq_smp_store_release(p, v)					\
 do {									\
 	RISCV_FENCE(rw, w);						\
-	RSEQ_WRITE_ONCE(*(p), v);						\
+	RSEQ_WRITE_ONCE(*(p), v);					\
 } while (0)
 
 #define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip,	\
diff --git a/tools/testing/selftests/rseq/rseq-s390.h b/tools/testing/selftests/rseq/rseq-s390.h
index 46c92598acc7..33baaa9f9997 100644
--- a/tools/testing/selftests/rseq/rseq-s390.h
+++ b/tools/testing/selftests/rseq/rseq-s390.h
@@ -15,7 +15,7 @@
 
 #define rseq_smp_load_acquire(p)					\
 __extension__ ({							\
-	__typeof(*p) ____p1 = RSEQ_READ_ONCE(*p);			\
+	rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));	\
 	rseq_barrier();							\
 	____p1;								\
 })
@@ -25,7 +25,7 @@ __extension__ ({							\
 #define rseq_smp_store_release(p, v)					\
 do {									\
 	rseq_barrier();							\
-	RSEQ_WRITE_ONCE(*p, v);						\
+	RSEQ_WRITE_ONCE(*(p), v);					\
 } while (0)
 
 #ifdef __s390x__
diff --git a/tools/testing/selftests/rseq/rseq-x86.h b/tools/testing/selftests/rseq/rseq-x86.h
index fb65ef54b0fb..a2aa428ba151 100644
--- a/tools/testing/selftests/rseq/rseq-x86.h
+++ b/tools/testing/selftests/rseq/rseq-x86.h
@@ -42,7 +42,7 @@
 
 #define rseq_smp_load_acquire(p)					\
 __extension__ ({							\
-	__typeof(*p) ____p1 = RSEQ_READ_ONCE(*p);			\
+	rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p));	\
 	rseq_barrier();							\
 	____p1;								\
 })
@@ -52,7 +52,7 @@ __extension__ ({							\
 #define rseq_smp_store_release(p, v)					\
 do {									\
 	rseq_barrier();							\
-	RSEQ_WRITE_ONCE(*p, v);						\
+	RSEQ_WRITE_ONCE(*(p), v);					\
 } while (0)
 
 #define __RSEQ_ASM_DEFINE_TABLE(label, version, flags,			\
-- 
2.25.1