Merge branch 'for-next/read-barrier-depends' into for-next/core

* for-next/read-barrier-depends:
  : Allow architectures to override __READ_ONCE()
  arm64: Reduce the number of header files pulled into vmlinux.lds.S
  compiler.h: Move compiletime_assert() macros into compiler_types.h
  checkpatch: Remove checks relating to [smp_]read_barrier_depends()
  include/linux: Remove smp_read_barrier_depends() from comments
  tools/memory-model: Remove smp_read_barrier_depends() from informal doc
  Documentation/barriers/kokr: Remove references to [smp_]read_barrier_depends()
  Documentation/barriers: Remove references to [smp_]read_barrier_depends()
  locking/barriers: Remove definitions for [smp_]read_barrier_depends()
  alpha: Replace smp_read_barrier_depends() usage with smp_[r]mb()
  vhost: Remove redundant use of read_barrier_depends() barrier
  asm/rwonce: Don't pull <asm/barrier.h> into 'asm-generic/rwonce.h'
  asm/rwonce: Remove smp_read_barrier_depends() invocation
  alpha: Override READ_ONCE() with barriered implementation
  asm/rwonce: Allow __READ_ONCE to be overridden by the architecture
  compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h
  tools: bpf: Use local copy of headers including uapi/linux/filter.h

1 files changed, 2 insertions, 132 deletions

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 204e76856435..59f7194fdf08 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -230,28 +230,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
 #endif
 
-/*
- * Prevent the compiler from merging or refetching reads or writes. The
- * compiler is also forbidden from reordering successive instances of
- * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
- * particular ordering. One way to make the compiler aware of ordering is to
- * put the two invocations of READ_ONCE or WRITE_ONCE in different C
- * statements.
- *
- * These two macros will also work on aggregate data types like structs or
- * unions.
- *
- * Their two major use cases are: (1) Mediating communication between
- * process-level code and irq/NMI handlers, all running on the same CPU,
- * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
- * mutilate accesses that either do not require ordering or that interact
- * with an explicit memory barrier or atomic instruction that provides the
- * required ordering.
- */
-#include <asm/barrier.h>
-#include <linux/kasan-checks.h>
-#include <linux/kcsan-checks.h>
-
 /**
  * data_race - mark an expression as containing intentional data races
  *
@@ -272,65 +250,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	__v;								\
 })
 
-/*
- * Use __READ_ONCE() instead of READ_ONCE() if you do not require any
- * atomicity or dependency ordering guarantees. Note that this may result
- * in tears!
- */
-#define __READ_ONCE(x)	(*(const volatile __unqual_scalar_typeof(x) *)&(x))
-
-#define __READ_ONCE_SCALAR(x)						\
-({									\
-	__unqual_scalar_typeof(x) __x = __READ_ONCE(x);			\
-	smp_read_barrier_depends();					\
-	(typeof(x))__x;							\
-})
-
-#define READ_ONCE(x)							\
-({									\
-	compiletime_assert_rwonce_type(x);				\
-	__READ_ONCE_SCALAR(x);						\
-})
-
-#define __WRITE_ONCE(x, val)						\
-do {									\
-	*(volatile typeof(x) *)&(x) = (val);				\
-} while (0)
-
-#define WRITE_ONCE(x, val)						\
-do {									\
-	compiletime_assert_rwonce_type(x);				\
-	__WRITE_ONCE(x, val);						\
-} while (0)
-
-static __no_sanitize_or_inline
-unsigned long __read_once_word_nocheck(const void *addr)
-{
-	return __READ_ONCE(*(unsigned long *)addr);
-}
-
-/*
- * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a
- * word from memory atomically but without telling KASAN/KCSAN. This is
- * usually used by unwinding code when walking the stack of a running process.
- */
-#define READ_ONCE_NOCHECK(x)						\
-({									\
-	unsigned long __x;						\
-	compiletime_assert(sizeof(x) == sizeof(__x),			\
-		"Unsupported access size for READ_ONCE_NOCHECK().");	\
-	__x = __read_once_word_nocheck(&(x));				\
-	smp_read_barrier_depends();					\
-	(typeof(x))__x;							\
-})
-
-static __no_kasan_or_inline
-unsigned long read_word_at_a_time(const void *addr)
-{
-	kasan_check_read(addr, 1);
-	return *(unsigned long *)addr;
-}
-
 #endif /* __KERNEL__ */
 
 /*
@@ -354,57 +273,6 @@ static inline void *offset_to_ptr(const int *off)
 
 #endif /* __ASSEMBLY__ */
 
-/* Compile time object size, -1 for unknown */
-#ifndef __compiletime_object_size
-# define __compiletime_object_size(obj) -1
-#endif
-#ifndef __compiletime_warning
-# define __compiletime_warning(message)
-#endif
-#ifndef __compiletime_error
-# define __compiletime_error(message)
-#endif
-
-#ifdef __OPTIMIZE__
-# define __compiletime_assert(condition, msg, prefix, suffix)		\
-	do {								\
-		extern void prefix ## suffix(void) __compiletime_error(msg); \
-		if (!(condition))					\
-			prefix ## suffix();				\
-	} while (0)
-#else
-# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
-#endif
-
-#define _compiletime_assert(condition, msg, prefix, suffix) \
-	__compiletime_assert(condition, msg, prefix, suffix)
-
-/**
- * compiletime_assert - break build and emit msg if condition is false
- * @condition: a compile-time constant condition to check
- * @msg:       a message to emit if condition is false
- *
- * In tradition of POSIX assert, this macro will break the build if the
- * supplied condition is *false*, emitting the supplied error message if the
- * compiler has support to do so.
- */
-#define compiletime_assert(condition, msg) \
-	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
-
-#define compiletime_assert_atomic_type(t)				\
-	compiletime_assert(__native_word(t),				\
-		"Need native word sized stores/loads for atomicity.")
-
-/*
- * Yes, this permits 64-bit accesses on 32-bit architectures. These will
- * actually be atomic in some cases (namely Armv7 + LPAE), but for others we
- * rely on the access being split into 2x32-bit accesses for a 32-bit quantity
- * (e.g. a virtual address) and a strong prevailing wind.
- */
-#define compiletime_assert_rwonce_type(t)					\
-	compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long),	\
-		"Unsupported access size for {READ,WRITE}_ONCE().")
-
 /* &a[0] degrades to a pointer: a different type from an array */
 #define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
 
@@ -414,4 +282,6 @@ static inline void *offset_to_ptr(const int *off)
  */
 #define prevent_tail_call_optimization()	mb()
 
+#include <asm/rwonce.h>
+
 #endif /* __LINUX_COMPILER_H */