From: Guo Ren <guo...@linux.alibaba.com>
Cache-block prefetch instructions are HINTs to the hardware to
indicate that software intends to perform a particular type of
memory access in the near future. Enable ARCH_HAS_PREFETCHW and
improve the arch_xchg for qspinlock xchg_tail.
Signed-off-by: Guo Ren <guo...@linux.alibaba.com>
Signed-off-by: Guo Ren <guo...@kernel.org>
---
arch/riscv/Kconfig | 15 +++++++++++++++
arch/riscv/include/asm/cmpxchg.h | 4 +++-
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/include/asm/insn-def.h | 5 +++++
arch/riscv/include/asm/processor.h | 13 +++++++++++++
arch/riscv/kernel/cpufeature.c | 1 +
6 files changed, 38 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e9ae6fa232c3..2c346fe169c1 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -617,6 +617,21 @@ config RISCV_ISA_ZICBOZ
If you don't know what to do here, say Y.
+config RISCV_ISA_ZICBOP
+ bool "Zicbop extension support for cache block prefetch"
+ depends on MMU
+ depends on RISCV_ALTERNATIVE
+ default y
+ help
+ Adds support to dynamically detect the presence of the ZICBOP
+ extension (Cache Block Prefetch Operations) and enable its
+ usage.
+
+ The Zicbop extension can be used to prefetch cache block for
+ read/write/instruction fetch.
+
+ If you don't know what to do here, say Y.
+
config TOOLCHAIN_HAS_ZIHINTPAUSE
bool
default y
diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h
index 702725727671..56eff7a9d2d2 100644
--- a/arch/riscv/include/asm/cmpxchg.h
+++ b/arch/riscv/include/asm/cmpxchg.h
@@ -11,6 +11,7 @@
#include <asm/barrier.h>
#include <asm/fence.h>
+#include <asm/processor.h>
#define __arch_xchg_masked(prepend, append, r, p, n) \
({ \
@@ -25,6 +26,7 @@
\
__asm__ __volatile__ ( \
prepend \
+ PREFETCHW_ASM(%5) \
"0: lr.w %0, %2\n" \
" and %1, %0, %z4\n" \
" or %1, %1, %z3\n" \
@@ -32,7 +34,7 @@
" bnez %1, 0b\n" \
append \
: "=&r" (__retx), "=&r" (__rc), "+A" (*(__ptr32b)) \
- : "rJ" (__newx), "rJ" (~__mask) \
+ : "rJ" (__newx), "rJ" (~__mask), "rJ" (__ptr32b) \
: "memory"); \
\
r = (__typeof__(*(p)))((__retx & __mask) >> __s); \
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index b7b58258f6c7..78b7b8b53778 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -58,6 +58,7 @@
#define RISCV_ISA_EXT_ZICSR 40
#define RISCV_ISA_EXT_ZIFENCEI 41
#define RISCV_ISA_EXT_ZIHPM 42
+#define RISCV_ISA_EXT_ZICBOP 43
#define RISCV_ISA_EXT_MAX 64
diff --git a/arch/riscv/include/asm/insn-def.h
b/arch/riscv/include/asm/insn-def.h
index 6960beb75f32..dc590d331894 100644
--- a/arch/riscv/include/asm/insn-def.h
+++ b/arch/riscv/include/asm/insn-def.h
@@ -134,6 +134,7 @@
#define RV_OPCODE_MISC_MEM RV_OPCODE(15)
#define RV_OPCODE_SYSTEM RV_OPCODE(115)
+#define RV_OPCODE_PREFETCH RV_OPCODE(19)
#define HFENCE_VVMA(vaddr, asid) \
INSN_R(OPCODE_SYSTEM, FUNC3(0), FUNC7(17), \
@@ -196,4 +197,8 @@
INSN_I(OPCODE_MISC_MEM, FUNC3(2), __RD(0), \
RS1(base), SIMM12(4))
+#define CBO_prefetchw(base) \
+ INSN_R(OPCODE_PREFETCH, FUNC3(6), FUNC7(0), \
+ RD(x0), RS1(base), RS2(x0))
+
#endif /* __ASM_INSN_DEF_H */
diff --git a/arch/riscv/include/asm/processor.h
b/arch/riscv/include/asm/processor.h
index de9da852f78d..7ad3a24212e8 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -12,6 +12,8 @@
#include <vdso/processor.h>
#include <asm/ptrace.h>
+#include <asm/insn-def.h>
+#include <asm/hwcap.h>
#ifdef CONFIG_64BIT
#define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
@@ -103,6 +105,17 @@ static inline void arch_thread_struct_whitelist(unsigned
long *offset,
#define KSTK_EIP(tsk) (ulong)(task_pt_regs(tsk)->epc)
#define KSTK_ESP(tsk) (ulong)(task_pt_regs(tsk)->sp)
+#define ARCH_HAS_PREFETCHW
+#define PREFETCHW_ASM(base) ALTERNATIVE(__nops(1), \
+ CBO_prefetchw(base), \
+ 0, \
+ RISCV_ISA_EXT_ZICBOP, \
+ CONFIG_RISCV_ISA_ZICBOP)
+static inline void prefetchw(const void *ptr)
+{
+ asm volatile(PREFETCHW_ASM(%0)
+ : : "r" (ptr) : "memory");
+}
/* Do necessary setup to start up a newly executed thread. */
extern void start_thread(struct pt_regs *regs,
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index ef7b4fd9e876..e0b897db0b97 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -159,6 +159,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
__RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
+ __RISCV_ISA_EXT_DATA(zicbop, RISCV_ISA_EXT_ZICBOP),
__RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
__RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
__RISCV_ISA_EXT_DATA(zifencei, RISCV_ISA_EXT_ZIFENCEI),
--
2.36.1
