compiler.h: take in recent linux updates for newer gcc support

Had to remove from original compiler-gcc: - things that deal with types, e.g. READ_ONCE macro and friends; - #define barrier(). This one would be better there at some point.
2017-09-12 10:27:57 +09:00
parent 230272438f
commit 2a46fd0b2d
3 changed files with 709 additions and 91 deletions
--- a/kernel/include/lwk/compiler-gcc.h
+++ b/kernel/include/lwk/compiler-gcc.h
@@ -1,36 +1,343 @@
-/* Never include this file directly.  Include <lwk/compiler.h> instead.  */
+#ifndef __LWK_COMPILER_H
+#error "Please don't include <linux/compiler-gcc.h> directly, include <lwk/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
- * NOTE: already defined in ihk/manycore/generic/include/ihk/cpu.h 
+
+/* The "volatile" is due to gcc bugs */
+/* XXX: barrier is also defined in lib/include/ihk/cpu.h,
+ * it would be cleaner to restore this here at some point, but we have
+ * quite a few C files not including either this or kernel's compiler.h
 * #define barrier() __asm__ __volatile__("": : :"memory")
 */
-
-/* This macro obfuscates arithmetic on a variable address so that gcc
-   shouldn't recognize the original var, and make assumptions about it */
 /*
+ * 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 proved 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)); })
+#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(a)	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.
+ * GCC does not warn about unused static inline functions for
+ * -Wunused-function.  This turns out to avoid the need for complex #ifdef
+ * directives.  Suppress the warning in clang as well by using "unused"
+ * function attribute, which is redundant but not harmful for gcc.
+ */
+#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) ||		\
+    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
+#define inline inline		__attribute__((always_inline,unused)) notrace
+#define __inline__ __inline__	__attribute__((always_inline,unused)) notrace
+#define __inline __inline	__attribute__((always_inline,unused)) notrace
+#else
+/* A lot of inline functions can cause havoc with function tracing */
+#define inline inline		__attribute__((unused)) notrace
+#define __inline__ __inline__	__attribute__((unused)) notrace
+#define __inline __inline	__attribute__((unused)) notrace
+#endif
+
+#define __always_inline	inline __attribute__((always_inline))
+#define  noinline	__attribute__((noinline))
+
+#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 __aligned_largest	__attribute__((aligned))
+#define __printf(a, b)		__attribute__((format(printf, a, b)))
+#define __scanf(a, b)		__attribute__((format(scanf, a, b)))
+#define __attribute_const__	__attribute__((__const__))
+#define __maybe_unused		__attribute__((unused))
+#define __always_unused		__attribute__((unused))
+#define __mode(x)               __attribute__((mode(x)))
+
+/* gcc version specific checks */
+
+#if GCC_VERSION < 30200
+# error Sorry, your compiler is too old - please upgrade it.
+#endif
+
+#if GCC_VERSION < 30300
+# define __used			__attribute__((__unused__))
+#else
+# define __used			__attribute__((__used__))
+#endif
+
+#ifdef CONFIG_GCOV_KERNEL
+# if GCC_VERSION < 30400
+#   error "GCOV profiling support for gcc versions below 3.4 not included"
+# endif /* __GNUC_MINOR__ */
+#endif /* CONFIG_GCOV_KERNEL */
+
+#if GCC_VERSION >= 30400
+#define __must_check		__attribute__((warn_unused_result))
+#define __malloc		__attribute__((__malloc__))
+#endif
+
+#if GCC_VERSION >= 40000
+
+/* GCC 4.1.[01] miscompiles __weak */
+#ifdef __KERNEL__
+# if GCC_VERSION >= 40100 &&  GCC_VERSION <= 40101
+#  error Your version of gcc miscompiles the __weak directive
+# endif
+#endif
+
+#define __used			__attribute__((__used__))
+#define __compiler_offsetof(a, b)					\
+	__builtin_offsetof(a, b)
+
+#if GCC_VERSION >= 40100
+# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
+#endif
+
+#if GCC_VERSION >= 40300
+/* Mark functions as cold. gcc will assume any path leading to a call
+ * to them will be unlikely.  This means a lot of manual unlikely()s
+ * are unnecessary now for any paths leading to the usual suspects
+ * like BUG(), printk(), panic() etc. [but let's keep them for now for
+ * older compilers]
+ *
+ * Early snapshots of gcc 4.3 don't support this and we can't detect this
+ * in the preprocessor, but we can live with this because they're unreleased.
+ * Maketime probing would be overkill here.
+ *
+ * gcc also has a __attribute__((__hot__)) to move hot functions into
+ * a special section, but I don't see any sense in this right now in
+ * the kernel context
+ */
+#define __cold			__attribute__((__cold__))
+
+#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+
+#ifndef __CHECKER__
+# define __compiletime_warning(message) __attribute__((warning(message)))
+# define __compiletime_error(message) __attribute__((error(message)))
+#endif /* __CHECKER__ */
+#endif /* GCC_VERSION >= 40300 */
+
+#if GCC_VERSION >= 40500
+
+#ifndef __CHECKER__
+#ifdef LATENT_ENTROPY_PLUGIN
+#define __latent_entropy __attribute__((latent_entropy))
+#endif
+#endif
+
+#ifdef CONFIG_STACK_VALIDATION
+#define annotate_unreachable() ({					\
+	asm("%c0:\t\n"							\
+	    ".pushsection .discard.unreachable\t\n"			\
+	    ".long %c0b - .\t\n"					\
+	    ".popsection\t\n" : : "i" (__LINE__));			\
+})
+#else
+#define annotate_unreachable()
+#endif
+
+/*
+ * Mark a position in code as unreachable.  This can be used to
+ * suppress control flow warnings after asm blocks that transfer
+ * control elsewhere.
+ *
+ * Early snapshots of gcc 4.5 don't support this and we can't detect
+ * this in the preprocessor, but we can live with this because they're
+ * unreleased.  Really, we need to have autoconf for the kernel.
+ */
+#define unreachable() \
+	do { annotate_unreachable(); __builtin_unreachable(); } while (0)
+
+/* Mark a function definition as prohibited from being cloned. */
+#define __noclone	__attribute__((__noclone__, __optimize__("no-tracer")))
+
+#ifdef RANDSTRUCT_PLUGIN
+#define __randomize_layout __attribute__((randomize_layout))
+#define __no_randomize_layout __attribute__((no_randomize_layout))
+#endif
+
+#endif /* GCC_VERSION >= 40500 */
+
+#if GCC_VERSION >= 40600
+
+/*
+ * When used with Link Time Optimization, gcc can optimize away C functions or
+ * variables which are referenced only from assembly code.  __visible tells the
+ * optimizer that something else uses this function or variable, thus preventing
+ * this.
+ */
+#define __visible	__attribute__((externally_visible))
+
+/*
+ * RANDSTRUCT_PLUGIN wants to use an anonymous struct, but it is only
+ * possible since GCC 4.6. To provide as much build testing coverage
+ * as possible, this is used for all GCC 4.6+ builds, and not just on
+ * RANDSTRUCT_PLUGIN builds.
+ */
+#define randomized_struct_fields_start	struct {
+#define randomized_struct_fields_end	} __randomize_layout;
+
+#endif /* GCC_VERSION >= 40600 */


-#define inline		inline		__attribute__((always_inline))
-#define __inline__	__inline__	__attribute__((always_inline))
-#define __inline	__inline	__attribute__((always_inline))
-#define __deprecated			__attribute__((deprecated))
-#define  noinline			__attribute__((noinline))
-#define __attribute_pure__		__attribute__((pure))
-#define __attribute_const__		__attribute__((__const__))
-#define __weak                          __attribute__((weak))
-#define __noreturn			__attribute__((noreturn))
+#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
+/*
+ * __assume_aligned(n, k): Tell the optimizer that the returned
+ * pointer can be assumed to be k modulo n. The second argument is
+ * optional (default 0), so we use a variadic macro to make the
+ * shorthand.
+ *
+ * Beware: Do not apply this to functions which may return
+ * ERR_PTRs. Also, it is probably unwise to apply it to functions
+ * returning extra information in the low bits (but in that case the
+ * compiler should see some alignment anyway, when the return value is
+ * massaged by 'flags = ptr & 3; ptr &= ~3;').
+ */
+#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
+#endif
+
+/*
+ * GCC 'asm goto' miscompiles certain code sequences:
+ *
+ *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
+ *
+ * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
+ *
+ * (asm goto is automatically volatile - the naming reflects this.)
+ */
+#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
+
+/*
+ * sparse (__CHECKER__) pretends to be gcc, but can't do constant
+ * folding in __builtin_bswap*() (yet), so don't set these for it.
+ */
+#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
+#if GCC_VERSION >= 40400
+#define __HAVE_BUILTIN_BSWAP32__
+#define __HAVE_BUILTIN_BSWAP64__
+#endif
+#if GCC_VERSION >= 40800
+#define __HAVE_BUILTIN_BSWAP16__
+#endif
+#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
+
+#if GCC_VERSION >= 70000
+#define KASAN_ABI_VERSION 5
+#elif GCC_VERSION >= 50000
+#define KASAN_ABI_VERSION 4
+#elif GCC_VERSION >= 40902
+#define KASAN_ABI_VERSION 3
+#endif
+
+#if GCC_VERSION >= 40902
+/*
+ * Tell the compiler that address safety instrumentation (KASAN)
+ * should not be applied to that function.
+ * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
+ */
+#define __no_sanitize_address __attribute__((no_sanitize_address))
+#endif
+
+#if GCC_VERSION >= 50100
+/*
+ * Mark structures as requiring designated initializers.
+ * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
+ */
+#define __designated_init __attribute__((designated_init))
+#endif
+
+#endif	/* gcc version >= 40000 specific checks */
+
+#if !defined(__noclone)
+#define __noclone	/* not needed */
+#endif
+
+#if !defined(__no_sanitize_address)
+#define __no_sanitize_address
+#endif
+
+/*
+ * A trick to suppress uninitialized variable warning without generating any
+ * code
+ */
+#define uninitialized_var(x) x = x