kern/latomic: new module

1 files changed, 149 insertions, 0 deletions

diff --git a/kern/latomic.h b/kern/latomic.h
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+/*
+ * Copyright (c) 2018 Agustina Arzille.
+ * Copyright (c) 2018 Richard Braun.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * CPU-local atomic operations.
+ *
+ * The latomic module provides operations that are "atomic on the local
+ * processor", i.e. interrupt-safe. Its interface is similar in spirit
+ * and purpose to that of the atomic module, and it can transparently
+ * replace it on single-processor configurations.
+ *
+ * Note that the only operations guaranteed to be truely atomic, i.e.
+ * to completely execute in a single atomic instruction, are loads and
+ * stores. All other operations may be implemented with multiple
+ * instructions, possibly disabling interrupts. The rationale is that
+ * atomic loads and stores are required for some types of access, such
+ * as memory-mapped device registers, while other operations only require
+ * interrupt safety.
+ *
+ * This header provides a generic implementation. Architectures can
+ * individually override any of the operations provided by this module.
+ */
+
+#ifndef KERN_LATOMIC_H
+#define KERN_LATOMIC_H
+
+#include <assert.h>
+
+#include <kern/macros.h>
+
+/*
+ * Memory orders for local atomic operations.
+ *
+ * These work like those in the atomic module, but are implemented
+ * with simple compiler barriers instead of full memory fences.
+ */
+#define LATOMIC_RELAXED __ATOMIC_RELAXED
+#define LATOMIC_ACQUIRE __ATOMIC_ACQUIRE
+#define LATOMIC_RELEASE __ATOMIC_RELEASE
+#define LATOMIC_ACQ_REL __ATOMIC_ACQ_REL
+#define LATOMIC_SEQ_CST __ATOMIC_SEQ_CST
+
+#include <kern/latomic_i.h>
+
+#define latomic_load(ptr, memorder)                                         \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, load)(ptr, memorder));             \
+MACRO_END
+
+#define latomic_store(ptr, val, memorder)                                   \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    latomic_select(ptr, store)(ptr, val, memorder);                         \
+MACRO_END
+
+#define latomic_swap(ptr, val, memorder)                                    \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, swap)(ptr, val, memorder));        \
+MACRO_END
+
+#define latomic_cas(ptr, oval, nval, memorder)                              \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, cas)(ptr, oval, nval, memorder));  \
+MACRO_END
+
+#define latomic_fetch_add(ptr, val, memorder)                               \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, fetch_add)(ptr, val, memorder));   \
+MACRO_END
+
+#define latomic_fetch_sub(ptr, val, memorder)                               \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, fetch_sub)(ptr, val, memorder));   \
+MACRO_END
+
+#define latomic_fetch_and(ptr, val, memorder)                               \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, fetch_and)(ptr, val, memorder));   \
+MACRO_END
+
+#define latomic_fetch_or(ptr, val, memorder)                                \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, fetch_or)(ptr, val, memorder));    \
+MACRO_END
+
+#define latomic_fetch_xor(ptr, val, memorder)                               \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    ((typeof(*(ptr)))latomic_select(ptr, fetch_xor)(ptr, val, memorder));   \
+MACRO_END
+
+#define latomic_add(ptr, val, memorder)                                     \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    latomic_select(ptr, add)(ptr, val, memorder);                           \
+MACRO_END
+
+#define latomic_sub(ptr, val, memorder)                                     \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    latomic_select(ptr, sub)(ptr, val, memorder);                           \
+MACRO_END
+
+#define latomic_and(ptr, val, memorder)                                     \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    latomic_select(ptr, and)(ptr, val, memorder);                           \
+MACRO_END
+
+#define latomic_or(ptr, val, memorder)                                      \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    latomic_select(ptr, or)(ptr, val, memorder);                            \
+MACRO_END
+
+#define latomic_xor(ptr, val, memorder)                                     \
+MACRO_BEGIN                                                                 \
+    assert(latomic_ptr_aligned(ptr));                                       \
+    latomic_select(ptr, xor)(ptr, val, memorder);                           \
+MACRO_END
+
+#define latomic_fence(memorder)             \
+MACRO_BEGIN                                 \
+    assert(memorder != LATOMIC_RELAXED);    \
+    barrier();                              \
+MACRO_END
+
+#endif /* KERN_LATOMIC_H */