Revert "Retire GCC FORTIFY."
This reverts commit 067bdc9546557a1a107f2617d7d15b864ff493f1.
The angler/bullhead builds still use GCC, so I'll wait until they're turned down.
Bug: https://issuetracker.google.com/74404306
Change-Id: I777b08dd6ab5250d532b4b5cc56e9a790c13db20
diff --git a/libc/include/stdatomic.h b/libc/include/stdatomic.h
index 3c61334..013407e 100644
--- a/libc/include/stdatomic.h
+++ b/libc/include/stdatomic.h
@@ -33,7 +33,11 @@
#include <sys/cdefs.h>
#if defined(__cplusplus) && __cplusplus >= 201103L && defined(_USING_LIBCXX)
-# if __has_feature(cxx_atomic)
+# ifdef __clang__
+# if __has_feature(cxx_atomic)
+# define _STDATOMIC_HAVE_ATOMIC
+# endif
+# else /* gcc */
# define _STDATOMIC_HAVE_ATOMIC
# endif
#endif
@@ -146,6 +150,20 @@
# include <uchar.h> /* For char16_t and char32_t. */
#endif
+
+#ifdef __clang__
+# if __has_extension(c_atomic) || __has_extension(cxx_atomic)
+# define __CLANG_ATOMICS
+# else
+# error "stdatomic.h does not support your compiler"
+# endif
+# if __has_builtin(__sync_swap)
+# define __HAS_BUILTIN_SYNC_SWAP
+# endif
+#else
+# define __GNUC_ATOMICS
+#endif
+
/*
* 7.17.1 Atomic lock-free macros.
*/
@@ -185,8 +203,13 @@
* 7.17.2 Initialization.
*/
+#if defined(__CLANG_ATOMICS)
#define ATOMIC_VAR_INIT(value) (value)
#define atomic_init(obj, value) __c11_atomic_init(obj, value)
+#else
+#define ATOMIC_VAR_INIT(value) { .__val = (value) }
+#define atomic_init(obj, value) ((void)((obj)->__val = (value)))
+#endif
/*
* Clang and recent GCC both provide predefined macros for the memory
@@ -235,24 +258,63 @@
* 7.17.4 Fences.
*/
-static __inline void atomic_thread_fence(memory_order __order __attribute__((unused))) {
+static __inline void
+atomic_thread_fence(memory_order __order __attribute__((unused)))
+{
+
+#ifdef __CLANG_ATOMICS
__c11_atomic_thread_fence(__order);
+#elif defined(__GNUC_ATOMICS)
+ __atomic_thread_fence(__order);
+#else
+ __sync_synchronize();
+#endif
}
-static __inline void atomic_signal_fence(memory_order __order __attribute__((unused))) {
+static __inline void
+atomic_signal_fence(memory_order __order __attribute__((unused)))
+{
+
+#ifdef __CLANG_ATOMICS
__c11_atomic_signal_fence(__order);
+#elif defined(__GNUC_ATOMICS)
+ __atomic_signal_fence(__order);
+#else
+ __asm volatile ("" ::: "memory");
+#endif
}
/*
* 7.17.5 Lock-free property.
*/
-#define atomic_is_lock_free(obj) __c11_atomic_is_lock_free(sizeof(*(obj)))
+#if defined(_KERNEL)
+/* Atomics in kernelspace are always lock-free. */
+#define atomic_is_lock_free(obj) \
+ ((void)(obj), (_Bool)1)
+#elif defined(__CLANG_ATOMICS)
+#define atomic_is_lock_free(obj) \
+ __c11_atomic_is_lock_free(sizeof(*(obj)))
+#elif defined(__GNUC_ATOMICS)
+#define atomic_is_lock_free(obj) \
+ __atomic_is_lock_free(sizeof((obj)->__val), &(obj)->__val)
+#else
+#define atomic_is_lock_free(obj) \
+ ((void)(obj), sizeof((obj)->__val) <= sizeof(void *))
+#endif
/*
* 7.17.6 Atomic integer types.
*/
+#ifndef __CLANG_ATOMICS
+/*
+ * No native support for _Atomic(). Place object in structure to prevent
+ * most forms of direct non-atomic access.
+ */
+#define _Atomic(T) struct { T volatile __val; }
+#endif
+
typedef _Atomic(bool) atomic_bool;
typedef _Atomic(char) atomic_char;
typedef _Atomic(signed char) atomic_schar;
@@ -301,6 +363,7 @@
* Compiler-specific operations.
*/
+#if defined(__CLANG_ATOMICS)
#define atomic_compare_exchange_strong_explicit(object, expected, \
desired, success, failure) \
__c11_atomic_compare_exchange_strong(object, expected, desired, \
@@ -325,11 +388,91 @@
__c11_atomic_load(object, order)
#define atomic_store_explicit(object, desired, order) \
__c11_atomic_store(object, desired, order)
+#elif defined(__GNUC_ATOMICS)
+#define atomic_compare_exchange_strong_explicit(object, expected, \
+ desired, success, failure) \
+ __atomic_compare_exchange_n(&(object)->__val, expected, \
+ desired, 0, success, failure)
+#define atomic_compare_exchange_weak_explicit(object, expected, \
+ desired, success, failure) \
+ __atomic_compare_exchange_n(&(object)->__val, expected, \
+ desired, 1, success, failure)
+#define atomic_exchange_explicit(object, desired, order) \
+ __atomic_exchange_n(&(object)->__val, desired, order)
+#define atomic_fetch_add_explicit(object, operand, order) \
+ __atomic_fetch_add(&(object)->__val, operand, order)
+#define atomic_fetch_and_explicit(object, operand, order) \
+ __atomic_fetch_and(&(object)->__val, operand, order)
+#define atomic_fetch_or_explicit(object, operand, order) \
+ __atomic_fetch_or(&(object)->__val, operand, order)
+#define atomic_fetch_sub_explicit(object, operand, order) \
+ __atomic_fetch_sub(&(object)->__val, operand, order)
+#define atomic_fetch_xor_explicit(object, operand, order) \
+ __atomic_fetch_xor(&(object)->__val, operand, order)
+#define atomic_load_explicit(object, order) \
+ __atomic_load_n(&(object)->__val, order)
+#define atomic_store_explicit(object, desired, order) \
+ __atomic_store_n(&(object)->__val, desired, order)
+#else
+#define __atomic_apply_stride(object, operand) \
+ (((__typeof__((object)->__val))0) + (operand))
+#define atomic_compare_exchange_strong_explicit(object, expected, \
+ desired, success, failure) __extension__ ({ \
+ __typeof__(expected) __ep = (expected); \
+ __typeof__(*__ep) __e = *__ep; \
+ (void)(success); (void)(failure); \
+ (bool)((*__ep = __sync_val_compare_and_swap(&(object)->__val, \
+ __e, desired)) == __e); \
+})
+#define atomic_compare_exchange_weak_explicit(object, expected, \
+ desired, success, failure) \
+ atomic_compare_exchange_strong_explicit(object, expected, \
+ desired, success, failure)
+#ifdef __HAS_BUILTIN_SYNC_SWAP
+/* Clang provides a full-barrier atomic exchange - use it if available. */
+#define atomic_exchange_explicit(object, desired, order) \
+ ((void)(order), __sync_swap(&(object)->__val, desired))
+#else
+/*
+ * __sync_lock_test_and_set() is only an acquire barrier in theory (although in
+ * practice it is usually a full barrier) so we need an explicit barrier before
+ * it.
+ */
+#define atomic_exchange_explicit(object, desired, order) \
+__extension__ ({ \
+ __typeof__(object) __o = (object); \
+ __typeof__(desired) __d = (desired); \
+ (void)(order); \
+ __sync_synchronize(); \
+ __sync_lock_test_and_set(&(__o)->__val, __d); \
+})
+#endif
+#define atomic_fetch_add_explicit(object, operand, order) \
+ ((void)(order), __sync_fetch_and_add(&(object)->__val, \
+ __atomic_apply_stride(object, operand)))
+#define atomic_fetch_and_explicit(object, operand, order) \
+ ((void)(order), __sync_fetch_and_and(&(object)->__val, operand))
+#define atomic_fetch_or_explicit(object, operand, order) \
+ ((void)(order), __sync_fetch_and_or(&(object)->__val, operand))
+#define atomic_fetch_sub_explicit(object, operand, order) \
+ ((void)(order), __sync_fetch_and_sub(&(object)->__val, \
+ __atomic_apply_stride(object, operand)))
+#define atomic_fetch_xor_explicit(object, operand, order) \
+ ((void)(order), __sync_fetch_and_xor(&(object)->__val, operand))
+#define atomic_load_explicit(object, order) \
+ ((void)(order), __sync_fetch_and_add(&(object)->__val, 0))
+#define atomic_store_explicit(object, desired, order) \
+ ((void)atomic_exchange_explicit(object, desired, order))
+#endif
/*
* Convenience functions.
+ *
+ * Don't provide these in kernel space. In kernel space, we should be
+ * disciplined enough to always provide explicit barriers.
*/
+#ifndef _KERNEL
#define atomic_compare_exchange_strong(object, expected, desired) \
atomic_compare_exchange_strong_explicit(object, expected, \
desired, memory_order_seq_cst, memory_order_seq_cst)
@@ -352,6 +495,7 @@
atomic_load_explicit(object, memory_order_seq_cst)
#define atomic_store(object, desired) \
atomic_store_explicit(object, desired, memory_order_seq_cst)
+#endif /* !_KERNEL */
/*
* 7.17.8 Atomic flag type and operations.
@@ -366,21 +510,36 @@
#define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(false) }
-static __inline bool atomic_flag_test_and_set_explicit(volatile atomic_flag *__object, memory_order __order) {
+static __inline bool
+atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
+ memory_order __order)
+{
return (atomic_exchange_explicit(&__object->__flag, 1, __order));
}
-static __inline void atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order) {
+static __inline void
+atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
+{
+
atomic_store_explicit(&__object->__flag, 0, __order);
}
-static __inline bool atomic_flag_test_and_set(volatile atomic_flag *__object) {
- return (atomic_flag_test_and_set_explicit(__object, memory_order_seq_cst));
+#ifndef _KERNEL
+static __inline bool
+atomic_flag_test_and_set(volatile atomic_flag *__object)
+{
+
+ return (atomic_flag_test_and_set_explicit(__object,
+ memory_order_seq_cst));
}
-static __inline void atomic_flag_clear(volatile atomic_flag *__object) {
+static __inline void
+atomic_flag_clear(volatile atomic_flag *__object)
+{
+
atomic_flag_clear_explicit(__object, memory_order_seq_cst);
}
+#endif /* !_KERNEL */
#endif /* <atomic> unavailable */