1 files changed, 133 insertions, 0 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
new file mode 100644
index 000000000..371e560d1
--- /dev/null
+++ b/include/linux/compiler-gcc.h
@@ -0,0 +1,133 @@
+#ifndef __LINUX_COMPILER_H
+#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
+#endif
+
+/*
+ * Common definitions for all gcc versions go here.
+ */
+#define GCC_VERSION (__GNUC__ * 10000 \
+		   + __GNUC_MINOR__ * 100 \
+		   + __GNUC_PATCHLEVEL__)
+
+/* Optimization barrier */
+
+/* The "volatile" is due to gcc bugs */
+#define barrier() __asm__ __volatile__("": : :"memory")
+/*
+ * This version is i.e. to prevent dead stores elimination on @ptr
+ * where gcc and llvm may behave differently when otherwise using
+ * normal barrier(): while gcc behavior gets along with a normal
+ * barrier(), llvm needs an explicit input variable to be assumed
+ * clobbered. The issue is as follows: while the inline asm might
+ * access any memory it wants, the compiler could have fit all of
+ * @ptr into memory registers instead, and since @ptr never escaped
+ * from that, it proofed that the inline asm wasn't touching any of
+ * it. This version works well with both compilers, i.e. we're telling
+ * the compiler that the inline asm absolutely may see the contents
+ * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
+ */
+#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
+
+/*
+ * This macro obfuscates arithmetic on a variable address so that gcc
+ * shouldn't recognize the original var, and make assumptions about it.
+ *
+ * This is needed because the C standard makes it undefined to do
+ * pointer arithmetic on "objects" outside their boundaries and the
+ * gcc optimizers assume this is the case. In particular they
+ * assume such arithmetic does not wrap.
+ *
+ * A miscompilation has been observed because of this on PPC.
+ * To work around it we hide the relationship of the pointer and the object
+ * using this macro.
+ *
+ * Versions of the ppc64 compiler before 4.1 had a bug where use of
+ * RELOC_HIDE could trash r30. The bug can be worked around by changing
+ * the inline assembly constraint from =g to =r, in this particular
+ * case either is valid.
+ */
+#define RELOC_HIDE(ptr, off)					\
+  ({ unsigned long __ptr;					\
+    __asm__ ("" : "=r"(__ptr) : "0"(ptr));		\
+    (typeof(ptr)) (__ptr + (off)); })
+
+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var))
+
+#ifdef __CHECKER__
+#define __must_be_array(arr) 0
+#else
+/* &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]))
+#endif
+
+/*
+ * Force always-inline if the user requests it so via the .config,
+ * or if gcc is too old:
+ */
+#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
+    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
+# define inline		inline		__attribute__((always_inline)) notrace
+# define __inline__	__inline__	__attribute__((always_inline)) notrace
+# define __inline	__inline	__attribute__((always_inline)) notrace
+#else
+/* A lot of inline functions can cause havoc with function tracing */
+# define inline		inline		notrace
+# define __inline__	__inline__	notrace
+# define __inline	__inline	notrace
+#endif
+
+#define __deprecated			__attribute__((deprecated))
+#define __packed			__attribute__((packed))
+#define __weak				__attribute__((weak))
+#define __alias(symbol)		__attribute__((alias(#symbol)))
+
+/*
+ * it doesn't make sense on ARM (currently the only user of __naked) to trace
+ * naked functions because then mcount is called without stack and frame pointer
+ * being set up and there is no chance to restore the lr register to the value
+ * before mcount was called.
+ *
+ * The asm() bodies of naked functions often depend on standard calling conventions,
+ * therefore they must be noinline and noclone.  GCC 4.[56] currently fail to enforce
+ * this, so we must do so ourselves.  See GCC PR44290.
+ */
+#define __naked				__attribute__((naked)) noinline __noclone notrace
+
+#define __noreturn			__attribute__((noreturn))
+
+/*
+ * From the GCC manual:
+ *
+ * Many functions have no effects except the return value and their
+ * return value depends only on the parameters and/or global
+ * variables.  Such a function can be subject to common subexpression
+ * elimination and loop optimization just as an arithmetic operator
+ * would be.
+ * [...]
+ */
+#define __pure				__attribute__((pure))
+#define __aligned(x)			__attribute__((aligned(x)))
+#define __printf(a, b)			__attribute__((format(printf, a, b)))
+#define __scanf(a, b)			__attribute__((format(scanf, a, b)))
+#define  noinline			__attribute__((noinline))
+#define __attribute_const__		__attribute__((__const__))
+#define __maybe_unused			__attribute__((unused))
+#define __always_unused			__attribute__((unused))
+
+#define __gcc_header(x) #x
+#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
+#define gcc_header(x) _gcc_header(x)
+#include gcc_header(__GNUC__)
+
+#if !defined(__noclone)
+#define __noclone	/* not needed */
+#endif
+
+/*
+ * A trick to suppress uninitialized variable warning without generating any
+ * code
+ */
+#define uninitialized_var(x) x = x
+
+#define __always_inline		inline __attribute__((always_inline))