From: guoren@kernel.org
To: guoren@kernel.org, arnd@arndb.de, will@kernel.org,
peterz@infradead.org, boqun.feng@gmail.com, mark.rutland@arm.com
Cc: linux-csky@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, Guo Ren <guoren@linux.alibaba.com>
Subject: [PATCH] csky: Add qspinlock support
Date: Sun, 31 Jul 2022 05:47:41 -0400 [thread overview]
Message-ID: <20220731094741.3770926-1-guoren@kernel.org> (raw)
From: Guo Ren <guoren@linux.alibaba.com>
Enable qspinlock by the requirements mentioned in a8ad07e5240c9
("asm-generic: qspinlock: Indicate the use of mixed-size atomics").
C-SKY only has "ldex/stex" for all atomic operations. So csky give a
strong forward guarantee for "ldex/stex." That means when ldex grabbed
the cache line into $L1, it would block other cores from snooping the
address with several cycles. The atomic_fetch_add & xchg16 has the same
forward guarantee level in C-SKY.
Qspinlock has better code size and performance in a fast path.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
arch/csky/Kconfig | 1 +
arch/csky/include/asm/Kbuild | 4 ++--
arch/csky/include/asm/cmpxchg.h | 20 ++++++++++++++++++++
arch/csky/include/asm/spinlock.h | 12 ++++++++++++
arch/csky/include/asm/spinlock_types.h | 9 +++++++++
5 files changed, 44 insertions(+), 2 deletions(-)
create mode 100644 arch/csky/include/asm/spinlock.h
create mode 100644 arch/csky/include/asm/spinlock_types.h
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 41d7d614f7a2..333def12faef 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -8,6 +8,7 @@ config CSKY
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_QUEUED_RWLOCKS
+ select ARCH_USE_QUEUED_SPINLOCKS
select ARCH_WANT_FRAME_POINTERS if !CPU_CK610 && $(cc-option,-mbacktrace)
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
select COMMON_CLK
diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild
index 103207a58f97..1117c28cb7e8 100644
--- a/arch/csky/include/asm/Kbuild
+++ b/arch/csky/include/asm/Kbuild
@@ -3,10 +3,10 @@ generic-y += asm-offsets.h
generic-y += extable.h
generic-y += gpio.h
generic-y += kvm_para.h
-generic-y += spinlock.h
-generic-y += spinlock_types.h
+generic-y += mcs_spinlock.h
generic-y += qrwlock.h
generic-y += qrwlock_types.h
+generic-y += qspinlock.h
generic-y += parport.h
generic-y += user.h
generic-y += vmlinux.lds.h
diff --git a/arch/csky/include/asm/cmpxchg.h b/arch/csky/include/asm/cmpxchg.h
index 5b8faccd65e4..5f693fadb56c 100644
--- a/arch/csky/include/asm/cmpxchg.h
+++ b/arch/csky/include/asm/cmpxchg.h
@@ -15,6 +15,26 @@ extern void __bad_xchg(void);
__typeof__(*(ptr)) __ret; \
unsigned long tmp; \
switch (size) { \
+ case 2: { \
+ u32 ret; \
+ u32 shif = ((ulong)__ptr & 2) ? 16 : 0; \
+ u32 mask = 0xffff << shif; \
+ __ptr = (__typeof__(ptr))((ulong)__ptr & ~2); \
+ __asm__ __volatile__ ( \
+ "1: ldex.w %0, (%4)\n" \
+ " and %1, %0, %2\n" \
+ " or %1, %1, %3\n" \
+ " stex.w %1, (%4)\n" \
+ " bez %1, 1b\n" \
+ : "=&r" (ret), "=&r" (tmp) \
+ : "r" (~mask), \
+ "r" ((u32)__new << shif), \
+ "r" (__ptr) \
+ : "memory"); \
+ __ret = (__typeof__(*(ptr))) \
+ ((ret & mask) >> shif); \
+ break; \
+ } \
case 4: \
asm volatile ( \
"1: ldex.w %0, (%3) \n" \
diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h
new file mode 100644
index 000000000000..83a2005341f5
--- /dev/null
+++ b/arch/csky/include/asm/spinlock.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_SPINLOCK_H
+#define __ASM_CSKY_SPINLOCK_H
+
+#include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
+
+/* See include/linux/spinlock.h */
+#define smp_mb__after_spinlock() smp_mb()
+
+#endif /* __ASM_CSKY_SPINLOCK_H */
diff --git a/arch/csky/include/asm/spinlock_types.h b/arch/csky/include/asm/spinlock_types.h
new file mode 100644
index 000000000000..75bdf3af80ba
--- /dev/null
+++ b/arch/csky/include/asm/spinlock_types.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_SPINLOCK_TYPES_H
+#define __ASM_CSKY_SPINLOCK_TYPES_H
+
+#include <asm-generic/qspinlock_types.h>
+#include <asm-generic/qrwlock_types.h>
+
+#endif /* __ASM_CSKY_SPINLOCK_TYPES_H */
--
2.36.1
reply other threads:[~2022-07-31 9:48 UTC|newest]
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