linux-kernel - [PATCH 3.16 001/366] arm64: add missing data types in smp_load_acquire/smp_store

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Date:   Sun, 11 Nov 2018 19:49:05 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Andre Przywara" <andre.przywara@....com>,
        "Will Deacon" <will.deacon@....com>
Subject: [PATCH 3.16 001/366] arm64: add missing data types in
 smp_load_acquire/smp_store_release

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andre Przywara <andre.przywara@....com>

commit 878a84d5a8a18a4ab241d40cebb791d6aedf5605 upstream.

Commit 8053871d0f7f ("smp: Fix smp_call_function_single_async()
locking") introduced a call to smp_load_acquire() with a u16 argument,
but we only cared about u32 and u64 types in that function so far.
This resulted in a compiler warning fortunately, pointing at an
uninitialized use. Due to the implementation structure the compiler
misses that bug in the smp_store_release(), though.
Add the u16 and u8 variants using ldarh/stlrh and ldarb/stlrb,
respectively. Together with the compiletime_assert_atomic_type() check
this should cover all cases now.

Acked-by: Will Deacon <will.deacon@....com>
Signed-off-by: Andre Przywara <andre.przywara@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/arm64/include/asm/barrier.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -64,6 +64,14 @@ do {									\
 		{ .__val = (__force typeof(*p)) (v) }; 			\
 	compiletime_assert_atomic_type(*p);				\
 	switch (sizeof(*p)) {						\
+	case 1:								\
+		asm volatile ("stlrb %w1, %0"				\
+				: "=Q" (*p) : "r" (v) : "memory");	\
+		break;							\
+	case 2:								\
+		asm volatile ("stlrh %w1, %0"				\
+				: "=Q" (*p) : "r" (v) : "memory");	\
+		break;							\
 	case 4:								\
 		asm volatile ("stlr %w1, %0"				\
 				: "=Q" (*p)				\
@@ -84,6 +92,14 @@ do {									\
 	typeof(*p) ___p1;						\
 	compiletime_assert_atomic_type(*p);				\
 	switch (sizeof(*p)) {						\
+	case 1:								\
+		asm volatile ("ldarb %w0, %1"				\
+			: "=r" (___p1) : "Q" (*p) : "memory");		\
+		break;							\
+	case 2:								\
+		asm volatile ("ldarh %w0, %1"				\
+			: "=r" (___p1) : "Q" (*p) : "memory");		\
+		break;							\
 	case 4:								\
 		asm volatile ("ldar %w0, %1"				\
 			: "=r" (___p1) : "Q" (*p) : "memory");		\