Changeset 7137f74c in mainline

Timestamp:

2018-07-19T21:02:13Z (7 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

514d561

Parents:

5a50430

Message:

Implement some of GCC's sync_* builtins in using <atomic.h>.

Location:

uspace/lib

Files:

• c/Makefile (modified) (1 diff)
• c/arch/arm32/include/libarch/atomic.h (modified) (1 diff)
• c/generic/atomic.c (moved) (moved from uspace/lib/cpp/src/__bits/glue.cpp ) (2 diffs)
• cpp/Makefile (modified) (1 diff)

uspace/lib/c/Makefile

@@ -51 +51 @@
         generic/libc.c \
         generic/ddi.c \
+        generic/atomic.c \
         generic/as.c \
         generic/bd.c \

uspace/lib/c/arch/arm32/include/libarch/atomic.h

@@ -52 +52 @@
         /*
          * The following instructions between labels 1 and 2 constitute a
-         * Restartable Atomic Seqeunce. Should the sequence be non-atomic,
+         * Restartable Atomic Sequence. Should the sequence be non-atomic,
          * the kernel will restart it.
          */

uspace/lib/c/generic/atomic.c

@@ -1 +1 @@
 /*
- * Copyright (c) 2018 Jaroslav Jindrak
+ * Copyright (c) 2018 CZ.NIC, z.s.p.o.
  * All rights reserved.
  *
@@ -27 +27 @@
  */
 
-/**
- * This file contains glue code that makes different
- * architectures pass.
- */
+#include <atomic.h>
 
 #ifdef PLATFORM_arm32
 
-/**
- * ARM32 does not have GCC atomic operations inlined by
- * the compiler, so we need to define stubs for our library
- * to compile on this architecture.
- * TODO: make this synchronized
+/*
+ * Older ARMs don't have atomic instructions, so we need to define a bunch
+ * of symbols for GCC to use.
  */
-extern "C"
+
+unsigned __sync_add_and_fetch_4(volatile void *vptr, unsigned val)
 {
-#define LIBCPP_GLUE_OP_AND_FETCH(NAME, OP, TYPE, SIZE) \
-    TYPE __sync_##NAME##_and_fetch_##SIZE (volatile void* vptr, TYPE val) \
-    { \
-        TYPE* ptr = (TYPE*)vptr; \
-        *ptr = *ptr OP val; \
-        return *ptr; \
-    }
+        return atomic_add((atomic_t *)vptr, val);
+}
 
-LIBCPP_GLUE_OP_AND_FETCH(add, +, unsigned, 4)
-LIBCPP_GLUE_OP_AND_FETCH(sub, -, unsigned, 4)
+unsigned __sync_sub_and_fetch_4(volatile void *vptr, unsigned val)
+{
+        return atomic_add((atomic_t *)vptr, -(atomic_signed_t)val);
+}
 
-#define LIBCPP_GLUE_CMP_AND_SWAP(TYPE, SIZE) \
-    TYPE __sync_val_compare_and_swap_##SIZE (TYPE* ptr, TYPE old_val, TYPE new_val) \
-    { \
-        if (*ptr == old_val) \
-            *ptr = new_val; \
-        return *ptr; \
-    }
+bool __sync_bool_compare_and_swap_4(volatile void *ptr, unsigned old_val, unsigned new_val)
+{
+        return cas((atomic_t *)ptr, old_val, new_val);
+}
 
-LIBCPP_GLUE_CMP_AND_SWAP(unsigned, 4)
+unsigned __sync_val_compare_and_swap_4(volatile void *ptr, unsigned old_val, unsigned new_val)
+{
+        while (true) {
+                if (__sync_bool_compare_and_swap_4(ptr, old_val, new_val)) {
+                        return old_val;
+                }
+
+                unsigned current = *(volatile unsigned *)ptr;
+                if (current != old_val)
+                        return current;
+
+                /* If the current value is the same as old_val, retry. */
+        }
 }
+
 #endif

uspace/lib/cpp/Makefile

@@ -53 +53 @@
         src/typeindex.cpp \
         src/typeinfo.cpp \
-        src/__bits/glue.cpp \
         src/__bits/runtime.cpp \
         src/__bits/trycatch.cpp \