[PATCH] linux/compiler.h: Split into compiler.h and compiler-types.h

From: Will Deacon
Date: Fri Oct 06 2017 - 08:50:14 EST

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linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.

Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining READ_ONCE, which means that all
users of READ_ONCE need to include asm/barrier.h to avoid splats such
as:

In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^

A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.

This patch splits compiler.h in two: compiler-types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE.

uapi/linux/stddef.h is then moved over to include linux/compiler-types.h,
which fixes the build.

Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
---
include/linux/compiler-clang.h | 2 +-
include/linux/compiler-gcc.h | 2 +-
include/linux/compiler-intel.h | 2 +-
include/linux/compiler-types.h | 274 +++++++++++++++++++++++++++++++++++++++++
include/linux/compiler.h | 265 +--------------------------------------
include/uapi/linux/stddef.h | 2 +-
scripts/headers_install.sh | 2 +-
7 files changed, 282 insertions(+), 267 deletions(-)
create mode 100644 include/linux/compiler-types.h

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index de179993e039..5947a3e6c0e6 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -1,4 +1,4 @@
-#ifndef __LINUX_COMPILER_H
+#ifndef __LINUX_COMPILER_TYPES_H
#error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead."
#endif

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 16d41de92ee3..ce8e965646ef 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -1,4 +1,4 @@
-#ifndef __LINUX_COMPILER_H
+#ifndef __LINUX_COMPILER_TYPES_H
#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
#endif

diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h
index d4c71132d07f..e438ac89c692 100644
--- a/include/linux/compiler-intel.h
+++ b/include/linux/compiler-intel.h
@@ -1,4 +1,4 @@
-#ifndef __LINUX_COMPILER_H
+#ifndef __LINUX_COMPILER_TYPES_H
#error "Please don't include <linux/compiler-intel.h> directly, include <linux/compiler.h> instead."
#endif

diff --git a/include/linux/compiler-types.h b/include/linux/compiler-types.h
new file mode 100644
index 000000000000..6b79a9bba9a7
--- /dev/null
+++ b/include/linux/compiler-types.h
@@ -0,0 +1,274 @@
+#ifndef __LINUX_COMPILER_TYPES_H
+#define __LINUX_COMPILER_TYPES_H
+
+#ifndef __ASSEMBLY__
+
+#ifdef __CHECKER__
+# define __user __attribute__((noderef, address_space(1)))
+# define __kernel __attribute__((address_space(0)))
+# define __safe __attribute__((safe))
+# define __force __attribute__((force))
+# define __nocast __attribute__((nocast))
+# define __iomem __attribute__((noderef, address_space(2)))
+# define __must_hold(x) __attribute__((context(x,1,1)))
+# define __acquires(x) __attribute__((context(x,0,1)))
+# define __releases(x) __attribute__((context(x,1,0)))
+# define __acquire(x) __context__(x,1)
+# define __release(x) __context__(x,-1)
+# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
+# define __percpu __attribute__((noderef, address_space(3)))
+# define __rcu __attribute__((noderef, address_space(4)))
+# define __private __attribute__((noderef))
+extern void __chk_user_ptr(const volatile void __user *);
+extern void __chk_io_ptr(const volatile void __iomem *);
+# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
+#else /* __CHECKER__ */
+# ifdef STRUCTLEAK_PLUGIN
+# define __user __attribute__((user))
+# else
+# define __user
+# endif
+# define __kernel
+# define __safe
+# define __force
+# define __nocast
+# define __iomem
+# define __chk_user_ptr(x) (void)0
+# define __chk_io_ptr(x) (void)0
+# define __builtin_warning(x, y...) (1)
+# define __must_hold(x)
+# define __acquires(x)
+# define __releases(x)
+# define __acquire(x) (void)0
+# define __release(x) (void)0
+# define __cond_lock(x,c) (c)
+# define __percpu
+# define __rcu
+# define __private
+# define ACCESS_PRIVATE(p, member) ((p)->member)
+#endif /* __CHECKER__ */
+
+/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
+#define ___PASTE(a,b) a##b
+#define __PASTE(a,b) ___PASTE(a,b)
+
+#ifdef __KERNEL__
+
+#ifdef __GNUC__
+#include <linux/compiler-gcc.h>
+#endif
+
+#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
+#define notrace __attribute__((hotpatch(0,0)))
+#else
+#define notrace __attribute__((no_instrument_function))
+#endif
+
+/* Intel compiler defines __GNUC__. So we will overwrite implementations
+ * coming from above header files here
+ */
+#ifdef __INTEL_COMPILER
+# include <linux/compiler-intel.h>
+#endif
+
+/* Clang compiler defines __GNUC__. So we will overwrite implementations
+ * coming from above header files here
+ */
+#ifdef __clang__
+#include <linux/compiler-clang.h>
+#endif
+
+/*
+ * Generic compiler-dependent macros required for kernel
+ * build go below this comment. Actual compiler/compiler version
+ * specific implementations come from the above header files
+ */
+
+struct ftrace_branch_data {
+ const char *func;
+ const char *file;
+ unsigned line;
+ union {
+ struct {
+ unsigned long correct;
+ unsigned long incorrect;
+ };
+ struct {
+ unsigned long miss;
+ unsigned long hit;
+ };
+ unsigned long miss_hit[2];
+ };
+};
+
+struct ftrace_likely_data {
+ struct ftrace_branch_data data;
+ unsigned long constant;
+};
+
+#endif /* __KERNEL__ */
+
+#endif /* __ASSEMBLY__ */
+
+#ifdef __KERNEL__
+/*
+ * Allow us to mark functions as 'deprecated' and have gcc emit a nice
+ * warning for each use, in hopes of speeding the functions removal.
+ * Usage is:
+ * int __deprecated foo(void)
+ */
+#ifndef __deprecated
+# define __deprecated /* unimplemented */
+#endif
+
+#ifdef MODULE
+#define __deprecated_for_modules __deprecated
+#else
+#define __deprecated_for_modules
+#endif
+
+#ifndef __must_check
+#define __must_check
+#endif
+
+#ifndef CONFIG_ENABLE_MUST_CHECK
+#undef __must_check
+#define __must_check
+#endif
+#ifndef CONFIG_ENABLE_WARN_DEPRECATED
+#undef __deprecated
+#undef __deprecated_for_modules
+#define __deprecated
+#define __deprecated_for_modules
+#endif
+
+#ifndef __malloc
+#define __malloc
+#endif
+
+/*
+ * Allow us to avoid 'defined but not used' warnings on functions and data,
+ * as well as force them to be emitted to the assembly file.
+ *
+ * As of gcc 3.4, static functions that are not marked with attribute((used))
+ * may be elided from the assembly file. As of gcc 3.4, static data not so
+ * marked will not be elided, but this may change in a future gcc version.
+ *
+ * NOTE: Because distributions shipped with a backported unit-at-a-time
+ * compiler in gcc 3.3, we must define __used to be __attribute__((used))
+ * for gcc >=3.3 instead of 3.4.
+ *
+ * In prior versions of gcc, such functions and data would be emitted, but
+ * would be warned about except with attribute((unused)).
+ *
+ * Mark functions that are referenced only in inline assembly as __used so
+ * the code is emitted even though it appears to be unreferenced.
+ */
+#ifndef __used
+# define __used /* unimplemented */
+#endif
+
+#ifndef __maybe_unused
+# define __maybe_unused /* unimplemented */
+#endif
+
+#ifndef __always_unused
+# define __always_unused /* unimplemented */
+#endif
+
+#ifndef noinline
+#define noinline
+#endif
+
+/*
+ * Rather then using noinline to prevent stack consumption, use
+ * noinline_for_stack instead. For documentation reasons.
+ */
+#define noinline_for_stack noinline
+
+#ifndef __always_inline
+#define __always_inline inline
+#endif
+
+#endif /* __KERNEL__ */
+
+/*
+ * From the GCC manual:
+ *
+ * Many functions do not examine any values except their arguments,
+ * and have no effects except the return value. Basically this is
+ * just slightly more strict class than the `pure' attribute above,
+ * since function is not allowed to read global memory.
+ *
+ * Note that a function that has pointer arguments and examines the
+ * data pointed to must _not_ be declared `const'. Likewise, a
+ * function that calls a non-`const' function usually must not be
+ * `const'. It does not make sense for a `const' function to return
+ * `void'.
+ */
+#ifndef __attribute_const__
+# define __attribute_const__ /* unimplemented */
+#endif
+
+#ifndef __designated_init
+# define __designated_init
+#endif
+
+#ifndef __latent_entropy
+# define __latent_entropy
+#endif
+
+#ifndef __randomize_layout
+# define __randomize_layout __designated_init
+#endif
+
+#ifndef __no_randomize_layout
+# define __no_randomize_layout
+#endif
+
+#ifndef randomized_struct_fields_start
+# define randomized_struct_fields_start
+# define randomized_struct_fields_end
+#endif
+
+/*
+ * Tell gcc if a function is cold. The compiler will assume any path
+ * directly leading to the call is unlikely.
+ */
+
+#ifndef __cold
+#define __cold
+#endif
+
+/* Simple shorthand for a section definition */
+#ifndef __section
+# define __section(S) __attribute__ ((__section__(#S)))
+#endif
+
+#ifndef __visible
+#define __visible
+#endif
+
+#ifndef __nostackprotector
+# define __nostackprotector
+#endif
+
+/*
+ * Assume alignment of return value.
+ */
+#ifndef __assume_aligned
+#define __assume_aligned(a, ...)
+#endif
+
+
+/* Are two types/vars the same type (ignoring qualifiers)? */
+#ifndef __same_type
+# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
+#endif
+
+/* Is this type a native word size -- useful for atomic operations */
+#ifndef __native_word
+# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
+#endif
+
+#endif /* __LINUX_COMPILER_TYPES_H */
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f260ff39f90f..4517662f128c 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -1,111 +1,12 @@
#ifndef __LINUX_COMPILER_H
#define __LINUX_COMPILER_H

-#ifndef __ASSEMBLY__
+#include <linux/compiler-types.h>

-#ifdef __CHECKER__
-# define __user __attribute__((noderef, address_space(1)))
-# define __kernel __attribute__((address_space(0)))
-# define __safe __attribute__((safe))
-# define __force __attribute__((force))
-# define __nocast __attribute__((nocast))
-# define __iomem __attribute__((noderef, address_space(2)))
-# define __must_hold(x) __attribute__((context(x,1,1)))
-# define __acquires(x) __attribute__((context(x,0,1)))
-# define __releases(x) __attribute__((context(x,1,0)))
-# define __acquire(x) __context__(x,1)
-# define __release(x) __context__(x,-1)
-# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
-# define __percpu __attribute__((noderef, address_space(3)))
-# define __rcu __attribute__((noderef, address_space(4)))
-# define __private __attribute__((noderef))
-extern void __chk_user_ptr(const volatile void __user *);
-extern void __chk_io_ptr(const volatile void __iomem *);
-# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
-#else /* __CHECKER__ */
-# ifdef STRUCTLEAK_PLUGIN
-# define __user __attribute__((user))
-# else
-# define __user
-# endif
-# define __kernel
-# define __safe
-# define __force
-# define __nocast
-# define __iomem
-# define __chk_user_ptr(x) (void)0
-# define __chk_io_ptr(x) (void)0
-# define __builtin_warning(x, y...) (1)
-# define __must_hold(x)
-# define __acquires(x)
-# define __releases(x)
-# define __acquire(x) (void)0
-# define __release(x) (void)0
-# define __cond_lock(x,c) (c)
-# define __percpu
-# define __rcu
-# define __private
-# define ACCESS_PRIVATE(p, member) ((p)->member)
-#endif /* __CHECKER__ */
-
-/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
-#define ___PASTE(a,b) a##b
-#define __PASTE(a,b) ___PASTE(a,b)
+#ifndef __ASSEMBLY__

#ifdef __KERNEL__

-#ifdef __GNUC__
-#include <linux/compiler-gcc.h>
-#endif
-
-#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
-#define notrace __attribute__((hotpatch(0,0)))
-#else
-#define notrace __attribute__((no_instrument_function))
-#endif
-
-/* Intel compiler defines __GNUC__. So we will overwrite implementations
- * coming from above header files here
- */
-#ifdef __INTEL_COMPILER
-# include <linux/compiler-intel.h>
-#endif
-
-/* Clang compiler defines __GNUC__. So we will overwrite implementations
- * coming from above header files here
- */
-#ifdef __clang__
-#include <linux/compiler-clang.h>
-#endif
-
-/*
- * Generic compiler-dependent macros required for kernel
- * build go below this comment. Actual compiler/compiler version
- * specific implementations come from the above header files
- */
-
-struct ftrace_branch_data {
- const char *func;
- const char *file;
- unsigned line;
- union {
- struct {
- unsigned long correct;
- unsigned long incorrect;
- };
- struct {
- unsigned long miss;
- unsigned long hit;
- };
- unsigned long miss_hit[2];
- };
-};
-
-struct ftrace_likely_data {
- struct ftrace_branch_data data;
- unsigned long constant;
-};
-
/*
* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
* to disable branch tracing on a per file basis.
@@ -332,6 +233,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
* with an explicit memory barrier or atomic instruction that provides the
* required ordering.
*/
+#include <asm/barrier.h>

#define __READ_ONCE(x, check) \
({ \
@@ -363,167 +265,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s

#endif /* __ASSEMBLY__ */

-#ifdef __KERNEL__
-/*
- * Allow us to mark functions as 'deprecated' and have gcc emit a nice
- * warning for each use, in hopes of speeding the functions removal.
- * Usage is:
- * int __deprecated foo(void)
- */
-#ifndef __deprecated
-# define __deprecated /* unimplemented */
-#endif
-
-#ifdef MODULE
-#define __deprecated_for_modules __deprecated
-#else
-#define __deprecated_for_modules
-#endif
-
-#ifndef __must_check
-#define __must_check
-#endif
-
-#ifndef CONFIG_ENABLE_MUST_CHECK
-#undef __must_check
-#define __must_check
-#endif
-#ifndef CONFIG_ENABLE_WARN_DEPRECATED
-#undef __deprecated
-#undef __deprecated_for_modules
-#define __deprecated
-#define __deprecated_for_modules
-#endif
-
-#ifndef __malloc
-#define __malloc
-#endif
-
-/*
- * Allow us to avoid 'defined but not used' warnings on functions and data,
- * as well as force them to be emitted to the assembly file.
- *
- * As of gcc 3.4, static functions that are not marked with attribute((used))
- * may be elided from the assembly file. As of gcc 3.4, static data not so
- * marked will not be elided, but this may change in a future gcc version.
- *
- * NOTE: Because distributions shipped with a backported unit-at-a-time
- * compiler in gcc 3.3, we must define __used to be __attribute__((used))
- * for gcc >=3.3 instead of 3.4.
- *
- * In prior versions of gcc, such functions and data would be emitted, but
- * would be warned about except with attribute((unused)).
- *
- * Mark functions that are referenced only in inline assembly as __used so
- * the code is emitted even though it appears to be unreferenced.
- */
-#ifndef __used
-# define __used /* unimplemented */
-#endif
-
-#ifndef __maybe_unused
-# define __maybe_unused /* unimplemented */
-#endif
-
-#ifndef __always_unused
-# define __always_unused /* unimplemented */
-#endif
-
-#ifndef noinline
-#define noinline
-#endif
-
-/*
- * Rather then using noinline to prevent stack consumption, use
- * noinline_for_stack instead. For documentation reasons.
- */
-#define noinline_for_stack noinline
-
-#ifndef __always_inline
-#define __always_inline inline
-#endif
-
-#endif /* __KERNEL__ */
-
-/*
- * From the GCC manual:
- *
- * Many functions do not examine any values except their arguments,
- * and have no effects except the return value. Basically this is
- * just slightly more strict class than the `pure' attribute above,
- * since function is not allowed to read global memory.
- *
- * Note that a function that has pointer arguments and examines the
- * data pointed to must _not_ be declared `const'. Likewise, a
- * function that calls a non-`const' function usually must not be
- * `const'. It does not make sense for a `const' function to return
- * `void'.
- */
-#ifndef __attribute_const__
-# define __attribute_const__ /* unimplemented */
-#endif
-
-#ifndef __designated_init
-# define __designated_init
-#endif
-
-#ifndef __latent_entropy
-# define __latent_entropy
-#endif
-
-#ifndef __randomize_layout
-# define __randomize_layout __designated_init
-#endif
-
-#ifndef __no_randomize_layout
-# define __no_randomize_layout
-#endif
-
-#ifndef randomized_struct_fields_start
-# define randomized_struct_fields_start
-# define randomized_struct_fields_end
-#endif
-
-/*
- * Tell gcc if a function is cold. The compiler will assume any path
- * directly leading to the call is unlikely.
- */
-
-#ifndef __cold
-#define __cold
-#endif
-
-/* Simple shorthand for a section definition */
-#ifndef __section
-# define __section(S) __attribute__ ((__section__(#S)))
-#endif
-
-#ifndef __visible
-#define __visible
-#endif
-
-#ifndef __nostackprotector
-# define __nostackprotector
-#endif
-
-/*
- * Assume alignment of return value.
- */
-#ifndef __assume_aligned
-#define __assume_aligned(a, ...)
-#endif
-
-
-/* Are two types/vars the same type (ignoring qualifiers)? */
-#ifndef __same_type
-# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
-#endif
-
-/* Is this type a native word size -- useful for atomic operations */
-#ifndef __native_word
-# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
-#endif
-
/* Compile time object size, -1 for unknown */
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h
index 621fa8ac4425..1ec6a7867c46 100644
--- a/include/uapi/linux/stddef.h
+++ b/include/uapi/linux/stddef.h
@@ -1,4 +1,4 @@
-#include <linux/compiler.h>
+#include <linux/compiler-types.h>

#ifndef __always_inline
#define __always_inline inline
diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh
index fdebd66f8fc1..bbb7f3d35289 100755
--- a/scripts/headers_install.sh
+++ b/scripts/headers_install.sh
@@ -33,7 +33,7 @@ do
sed -r \
-e 's/([ \t(])(__user|__force|__iomem)[ \t]/\1/g' \
-e 's/__attribute_const__([ \t]|$)/\1/g' \
- -e 's@^#include <linux/compiler.h>@@' \
+ -e 's@^#include <linux/compiler(|-types).h>@@' \
-e 's/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g' \
-e 's/(^|[ \t(])(inline|asm|volatile)([ \t(]|$)/\1__\2__\3/g' \
-e 's@#(ifndef|define|endif[ \t]*/[*])[ \t]*_UAPI@#\1 @' \
--
2.1.4

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