284 lines
9.5 KiB
C
284 lines
9.5 KiB
C
#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(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:
|
|
*/
|
|
#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 __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 __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))
|
|
|
|
/* 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))
|
|
#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 && GCC_VERSION < 40600
|
|
# 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
|
|
/*
|
|
* 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() __builtin_unreachable()
|
|
|
|
/* Mark a function definition as prohibited from being cloned. */
|
|
#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
|
|
|
|
#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))
|
|
#endif
|
|
|
|
|
|
#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)
|
|
|
|
#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
|
|
#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 */
|
|
|
|
#if 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
|
|
|
|
#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
|