diff --git a/xen/arch/riscv/include/asm/atomic.h b/xen/arch/riscv/include/asm/atomic.h new file mode 100644 index 0000000000..31b91a79c8 --- /dev/null +++ b/xen/arch/riscv/include/asm/atomic.h @@ -0,0 +1,280 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Taken and modified from Linux. + * + * The following changes were done: + * - * atomic##prefix##_*xchg_*(atomic##prefix##_t *v, c_t n) were updated + * to use__*xchg_generic() + * - drop casts in write_atomic() as they are unnecessary + * - drop introduction of WRITE_ONCE() and READ_ONCE(). + * Xen provides ACCESS_ONCE() + * - remove zero-length array access in read_atomic() + * - drop defines similar to pattern + * #define atomic_add_return_relaxed atomic_add_return_relaxed + * - move not RISC-V specific functions to asm-generic/atomics-ops.h + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Copyright (C) 2012 Regents of the University of California + * Copyright (C) 2017 SiFive + * Copyright (C) 2024 Vates SAS + */ + +#ifndef _ASM_RISCV_ATOMIC_H +#define _ASM_RISCV_ATOMIC_H + +#include + +#include +#include +#include +#include + +void __bad_atomic_size(void); + +/* + * Legacy from Linux kernel. For some reason they wanted to have ordered + * read/write access. Thereby read* is used instead of read*_cpu() + */ +static always_inline void read_atomic_size(const volatile void *p, + void *res, + unsigned int size) +{ + switch ( size ) + { + case 1: *(uint8_t *)res = readb(p); break; + case 2: *(uint16_t *)res = readw(p); break; + case 4: *(uint32_t *)res = readl(p); break; +#ifndef CONFIG_RISCV_32 + case 8: *(uint32_t *)res = readq(p); break; +#endif + default: __bad_atomic_size(); break; + } +} + +#define read_atomic(p) ({ \ + union { typeof(*(p)) val; char c[sizeof(*(p))]; } x_; \ + read_atomic_size(p, x_.c, sizeof(*(p))); \ + x_.val; \ +}) + +static always_inline void _write_atomic(volatile void *p, + unsigned long x, unsigned int size) +{ + switch ( size ) + { + case 1: writeb(x, p); break; + case 2: writew(x, p); break; + case 4: writel(x, p); break; +#ifndef CONFIG_RISCV_32 + case 8: writeq(x, p); break; +#endif + default: __bad_atomic_size(); break; + } +} + +#define write_atomic(p, x) \ +({ \ + typeof(*(p)) x_ = (x); \ + _write_atomic(p, x_, sizeof(*(p))); \ +}) + +static always_inline void _add_sized(volatile void *p, + unsigned long x, unsigned int size) +{ + switch ( size ) + { + case 1: + { + volatile uint8_t *ptr = p; + write_atomic(ptr, read_atomic(ptr) + x); + break; + } + case 2: + { + volatile uint16_t *ptr = p; + write_atomic(ptr, read_atomic(ptr) + x); + break; + } + case 4: + { + volatile uint32_t *ptr = p; + write_atomic(ptr, read_atomic(ptr) + x); + break; + } +#ifndef CONFIG_RISCV_32 + case 8: + { + volatile uint64_t *ptr = p; + write_atomic(ptr, read_atomic(ptr) + x); + break; + } +#endif + default: __bad_atomic_size(); break; + } +} + +#define add_sized(p, x) \ +({ \ + typeof(*(p)) x_ = (x); \ + _add_sized(p, x_, sizeof(*(p))); \ +}) + +#define __atomic_acquire_fence() \ + asm volatile ( RISCV_ACQUIRE_BARRIER ::: "memory" ) + +#define __atomic_release_fence() \ + asm volatile ( RISCV_RELEASE_BARRIER ::: "memory" ) + +/* + * First, the atomic ops that have no ordering constraints and therefor don't + * have the AQ or RL bits set. These don't return anything, so there's only + * one version to worry about. + */ +#define ATOMIC_OP(op, asm_op, unary_op, asm_type, c_type, prefix) \ +static inline \ +void atomic##prefix##_##op(c_type i, atomic##prefix##_t *v) \ +{ \ + asm volatile ( \ + " amo" #asm_op "." #asm_type " zero, %1, %0" \ + : "+A" (v->counter) \ + : "r" (unary_op i) \ + : "memory" ); \ +} \ + +/* + * Only CONFIG_GENERIC_ATOMIC64=y was ported to Xen that is the reason why + * last argument for ATOMIC_OP isn't used. + */ +#define ATOMIC_OPS(op, asm_op, unary_op) \ + ATOMIC_OP (op, asm_op, unary_op, w, int, ) + +ATOMIC_OPS(add, add, +) +ATOMIC_OPS(sub, add, -) +ATOMIC_OPS(and, and, +) +ATOMIC_OPS( or, or, +) +ATOMIC_OPS(xor, xor, +) + +#undef ATOMIC_OP +#undef ATOMIC_OPS + +#include + +/* + * Atomic ops that have ordered variant. + * There's two flavors of these: the arithmatic ops have both fetch and return + * versions, while the logical ops only have fetch versions. + */ +#define ATOMIC_FETCH_OP(op, asm_op, unary_op, asm_type, c_type, prefix) \ +static inline \ +c_type atomic##prefix##_fetch_##op(c_type i, atomic##prefix##_t *v) \ +{ \ + register c_type ret; \ + asm volatile ( \ + " amo" #asm_op "." #asm_type ".aqrl %1, %2, %0" \ + : "+A" (v->counter), "=r" (ret) \ + : "r" (unary_op i) \ + : "memory" ); \ + return ret; \ +} + +#define ATOMIC_OP_RETURN(op, asm_op, c_op, unary_op, asm_type, c_type, prefix) \ +static inline \ +c_type atomic##prefix##_##op##_return(c_type i, atomic##prefix##_t *v) \ +{ \ + return atomic##prefix##_fetch_##op(i, v) c_op (unary_op i); \ +} + +/* + * Only CONFIG_GENERIC_ATOMIC64=y was ported to Xen that is the reason why + * last argument of ATOMIC_FETCH_OP, ATOMIC_OP_RETURN isn't used. + */ +#define ATOMIC_OPS(op, asm_op, unary_op) \ + ATOMIC_FETCH_OP( op, asm_op, unary_op, w, int, ) \ + ATOMIC_OP_RETURN(op, asm_op, +, unary_op, w, int, ) + +ATOMIC_OPS(add, add, +) +ATOMIC_OPS(sub, add, -) + +#undef ATOMIC_OPS + +#define ATOMIC_OPS(op, asm_op) \ + ATOMIC_FETCH_OP(op, asm_op, +, w, int, ) + +ATOMIC_OPS(and, and) +ATOMIC_OPS( or, or) +ATOMIC_OPS(xor, xor) + +#undef ATOMIC_OPS + +#undef ATOMIC_FETCH_OP +#undef ATOMIC_OP_RETURN + +/* This is required to provide a full barrier on success. */ +static inline int atomic_add_unless(atomic_t *v, int a, int u) +{ + int prev, rc; + + asm volatile ( + "0: lr.w %[p], %[c]\n" + " beq %[p], %[u], 1f\n" + " add %[rc], %[p], %[a]\n" + " sc.w.aqrl %[rc], %[rc], %[c]\n" + " bnez %[rc], 0b\n" + "1:\n" + : [p] "=&r" (prev), [rc] "=&r" (rc), [c] "+A" (v->counter) + : [a] "r" (a), [u] "r" (u) + : "memory"); + return prev; +} + +static inline int atomic_sub_if_positive(atomic_t *v, int offset) +{ + int prev, rc; + + asm volatile ( + "0: lr.w %[p], %[c]\n" + " sub %[rc], %[p], %[o]\n" + " bltz %[rc], 1f\n" + " sc.w.aqrl %[rc], %[rc], %[c]\n" + " bnez %[rc], 0b\n" + "1:\n" + : [p] "=&r" (prev), [rc] "=&r" (rc), [c] "+A" (v->counter) + : [o] "r" (offset) + : "memory" ); + return prev - offset; +} + +/* + * atomic_{cmp,}xchg is required to have exactly the same ordering semantics as + * {cmp,}xchg and the operations that return. + */ +#define ATOMIC_OP(c_t, prefix) \ +static inline \ +c_t atomic##prefix##_xchg(atomic##prefix##_t *v, c_t n) \ +{ \ + return __xchg(&v->counter, n, sizeof(c_t)); \ +} \ +static inline \ +c_t atomic##prefix##_cmpxchg(atomic##prefix##_t *v, c_t o, c_t n) \ +{ \ + return __cmpxchg(&v->counter, o, n, sizeof(c_t)); \ +} + +#define ATOMIC_OPS() \ + ATOMIC_OP(int, ) + +ATOMIC_OPS() + +#undef ATOMIC_OPS +#undef ATOMIC_OP + +#endif /* _ASM_RISCV_ATOMIC_H */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/include/asm-generic/atomic-ops.h b/xen/include/asm-generic/atomic-ops.h new file mode 100644 index 0000000000..98dd907942 --- /dev/null +++ b/xen/include/asm-generic/atomic-ops.h @@ -0,0 +1,97 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * The header provides default implementations for every xen/atomic.h-provided + * forward inline declaration that can be synthesized from other atomic + * functions or being created from scratch. + */ +#ifndef _ASM_GENERIC_ATOMIC_OPS_H_ +#define _ASM_GENERIC_ATOMIC_OPS_H_ + +#include +#include + +#ifndef ATOMIC_READ +static inline int atomic_read(const atomic_t *v) +{ + return ACCESS_ONCE(v->counter); +} +#endif + +#ifndef _ATOMIC_READ +static inline int _atomic_read(atomic_t v) +{ + return v.counter; +} +#endif + +#ifndef ATOMIC_SET +static inline void atomic_set(atomic_t *v, int i) +{ + ACCESS_ONCE(v->counter) = i; +} +#endif + +#ifndef _ATOMIC_SET +static inline void _atomic_set(atomic_t *v, int i) +{ + v->counter = i; +} +#endif + +#ifndef ATOMIC_SUB_AND_TEST +static inline int atomic_sub_and_test(int i, atomic_t *v) +{ + return atomic_sub_return(i, v) == 0; +} +#endif + +#ifndef ATOMIC_INC_AND_TEST +static inline int atomic_inc_and_test(atomic_t *v) +{ + return atomic_add_return(1, v) == 0; +} +#endif + +#ifndef ATOMIC_INC +static inline void atomic_inc(atomic_t *v) +{ + atomic_add(1, v); +} +#endif + +#ifndef ATOMIC_INC_RETURN +static inline int atomic_inc_return(atomic_t *v) +{ + return atomic_add_return(1, v); +} +#endif + +#ifndef ATOMIC_DEC +static inline void atomic_dec(atomic_t *v) +{ + atomic_sub(1, v); +} +#endif + +#ifndef ATOMIC_DEC_RETURN +static inline int atomic_dec_return(atomic_t *v) +{ + return atomic_sub_return(1, v); +} +#endif + +#ifndef ATOMIC_DEC_AND_TEST +static inline int atomic_dec_and_test(atomic_t *v) +{ + return atomic_sub_return(1, v) == 0; +} +#endif + +#ifndef ATOMIC_ADD_NEGATIVE +static inline int atomic_add_negative(int i, atomic_t *v) +{ + return atomic_add_return(i, v) < 0; +} +#endif + +#endif /* _ASM_GENERIC_ATOMIC_OPS_H_ */