Replace the barrier functions in arch/riscv/include/asm/io.h with those defined in barrier.h, which is imported from Linux. This version is modified to remove the include statement of asm-generic/barrier.h, which is not available in U-Boot or required.
Signed-off-by: Lukas Auer lukas.auer@aisec.fraunhofer.de Reviewed-by: Bin Meng bmeng.cn@gmail.com Reviewed-by: Rick Chen rick@andestech.com ---
Changes in v4: None Changes in v3: None Changes in v2: None
arch/riscv/include/asm/barrier.h | 67 ++++++++++++++++++++++++++++++++ arch/riscv/include/asm/io.h | 11 ++---- 2 files changed, 71 insertions(+), 7 deletions(-) create mode 100644 arch/riscv/include/asm/barrier.h
diff --git a/arch/riscv/include/asm/barrier.h b/arch/riscv/include/asm/barrier.h new file mode 100644 index 0000000000..a3f60a8458 --- /dev/null +++ b/arch/riscv/include/asm/barrier.h @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2012 ARM Ltd. + * Copyright (C) 2013 Regents of the University of California + * Copyright (C) 2017 SiFive + * + * Taken from Linux arch/riscv/include/asm/barrier.h, which is based on + * arch/arm/include/asm/barrier.h + */ + +#ifndef _ASM_RISCV_BARRIER_H +#define _ASM_RISCV_BARRIER_H + +#ifndef __ASSEMBLY__ + +#define nop() __asm__ __volatile__ ("nop") + +#define RISCV_FENCE(p, s) \ + __asm__ __volatile__ ("fence " #p "," #s : : : "memory") + +/* These barriers need to enforce ordering on both devices or memory. */ +#define mb() RISCV_FENCE(iorw,iorw) +#define rmb() RISCV_FENCE(ir,ir) +#define wmb() RISCV_FENCE(ow,ow) + +/* These barriers do not need to enforce ordering on devices, just memory. */ +#define __smp_mb() RISCV_FENCE(rw,rw) +#define __smp_rmb() RISCV_FENCE(r,r) +#define __smp_wmb() RISCV_FENCE(w,w) + +#define __smp_store_release(p, v) \ +do { \ + compiletime_assert_atomic_type(*p); \ + RISCV_FENCE(rw,w); \ + WRITE_ONCE(*p, v); \ +} while (0) + +#define __smp_load_acquire(p) \ +({ \ + typeof(*p) ___p1 = READ_ONCE(*p); \ + compiletime_assert_atomic_type(*p); \ + RISCV_FENCE(r,rw); \ + ___p1; \ +}) + +/* + * This is a very specific barrier: it's currently only used in two places in + * the kernel, both in the scheduler. See include/linux/spinlock.h for the two + * orderings it guarantees, but the "critical section is RCsc" guarantee + * mandates a barrier on RISC-V. The sequence looks like: + * + * lr.aq lock + * sc lock <= LOCKED + * smp_mb__after_spinlock() + * // critical section + * lr lock + * sc.rl lock <= UNLOCKED + * + * The AQ/RL pair provides a RCpc critical section, but there's not really any + * way we can take advantage of that here because the ordering is only enforced + * on that one lock. Thus, we're just doing a full fence. + */ +#define smp_mb__after_spinlock() RISCV_FENCE(rw,rw) + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_RISCV_BARRIER_H */ diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h index 472814a13e..d01ed5bc9f 100644 --- a/arch/riscv/include/asm/io.h +++ b/arch/riscv/include/asm/io.h @@ -10,6 +10,7 @@ #ifdef __KERNEL__
#include <linux/types.h> +#include <asm/barrier.h> #include <asm/byteorder.h>
static inline void sync(void) @@ -91,13 +92,9 @@ static inline phys_addr_t virt_to_phys(void *vaddr) #define __raw_readl(a) __arch_getl(a) #define __raw_readq(a) __arch_getq(a)
-/* - * TODO: The kernel offers some more advanced versions of barriers, it might - * have some advantages to use them instead of the simple one here. - */ -#define dmb() __asm__ __volatile__ ("" : : : "memory") -#define __iormb() dmb() -#define __iowmb() dmb() +#define dmb() mb() +#define __iormb() rmb() +#define __iowmb() wmb()
static inline void writeb(u8 val, volatile void __iomem *addr) {