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368 lines
12 KiB
368 lines
12 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __LINUX_COMPILER_TYPES_H |
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#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." |
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#endif |
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/* |
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* Common definitions for all gcc versions go here. |
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*/ |
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#define GCC_VERSION (__GNUC__ * 10000 \ |
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+ __GNUC_MINOR__ * 100 \ |
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+ __GNUC_PATCHLEVEL__) |
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/* Optimization barrier */ |
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/* The "volatile" is due to gcc bugs */ |
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#define barrier() __asm__ __volatile__("": : :"memory") |
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/* |
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* This version is i.e. to prevent dead stores elimination on @ptr |
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* where gcc and llvm may behave differently when otherwise using |
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* normal barrier(): while gcc behavior gets along with a normal |
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* barrier(), llvm needs an explicit input variable to be assumed |
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* clobbered. The issue is as follows: while the inline asm might |
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* access any memory it wants, the compiler could have fit all of |
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* @ptr into memory registers instead, and since @ptr never escaped |
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* from that, it proved that the inline asm wasn't touching any of |
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* it. This version works well with both compilers, i.e. we're telling |
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* the compiler that the inline asm absolutely may see the contents |
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* of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 |
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*/ |
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#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") |
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/* |
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* This macro obfuscates arithmetic on a variable address so that gcc |
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* shouldn't recognize the original var, and make assumptions about it. |
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* |
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* This is needed because the C standard makes it undefined to do |
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* pointer arithmetic on "objects" outside their boundaries and the |
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* gcc optimizers assume this is the case. In particular they |
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* assume such arithmetic does not wrap. |
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* |
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* A miscompilation has been observed because of this on PPC. |
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* To work around it we hide the relationship of the pointer and the object |
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* using this macro. |
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* |
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* Versions of the ppc64 compiler before 4.1 had a bug where use of |
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* RELOC_HIDE could trash r30. The bug can be worked around by changing |
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* the inline assembly constraint from =g to =r, in this particular |
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* case either is valid. |
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*/ |
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#define RELOC_HIDE(ptr, off) \ |
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({ \ |
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unsigned long __ptr; \ |
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__asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ |
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(typeof(ptr)) (__ptr + (off)); \ |
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}) |
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/* Make the optimizer believe the variable can be manipulated arbitrarily. */ |
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#define OPTIMIZER_HIDE_VAR(var) \ |
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__asm__ ("" : "=r" (var) : "0" (var)) |
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#ifdef __CHECKER__ |
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#define __must_be_array(a) 0 |
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#else |
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/* &a[0] degrades to a pointer: a different type from an array */ |
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#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) |
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#endif |
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/* |
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* Feature detection for gnu_inline (gnu89 extern inline semantics). Either |
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* __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics, |
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* and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not |
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* defined so the gnu89 semantics are the default. |
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*/ |
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#ifdef __GNUC_STDC_INLINE__ |
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# define __gnu_inline __attribute__((gnu_inline)) |
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#else |
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# define __gnu_inline |
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#endif |
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/* |
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* Force always-inline if the user requests it so via the .config, |
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* or if gcc is too old. |
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* GCC does not warn about unused static inline functions for |
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* -Wunused-function. This turns out to avoid the need for complex #ifdef |
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* directives. Suppress the warning in clang as well by using "unused" |
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* function attribute, which is redundant but not harmful for gcc. |
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* Prefer gnu_inline, so that extern inline functions do not emit an |
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* externally visible function. This makes extern inline behave as per gnu89 |
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* semantics rather than c99. This prevents multiple symbol definition errors |
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* of extern inline functions at link time. |
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* A lot of inline functions can cause havoc with function tracing. |
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*/ |
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#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ |
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!defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) |
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#define inline \ |
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inline __attribute__((always_inline, unused)) notrace __gnu_inline |
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#else |
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#define inline inline __attribute__((unused)) notrace __gnu_inline |
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#endif |
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#define __inline__ inline |
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#define __inline inline |
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#define __always_inline inline __attribute__((always_inline)) |
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#define noinline __attribute__((noinline)) |
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#define __deprecated __attribute__((deprecated)) |
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#define __packed __attribute__((packed)) |
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#define __weak __attribute__((weak)) |
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#define __alias(symbol) __attribute__((alias(#symbol))) |
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#ifdef CONFIG_RETPOLINE |
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#define __noretpoline __attribute__((indirect_branch("keep"))) |
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#endif |
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/* |
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* it doesn't make sense on ARM (currently the only user of __naked) |
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* to trace naked functions because then mcount is called without |
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* stack and frame pointer being set up and there is no chance to |
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* restore the lr register to the value before mcount was called. |
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* |
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* The asm() bodies of naked functions often depend on standard calling |
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* conventions, therefore they must be noinline and noclone. |
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* |
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* GCC 4.[56] currently fail to enforce this, so we must do so ourselves. |
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* See GCC PR44290. |
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*/ |
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#define __naked __attribute__((naked)) noinline __noclone notrace |
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#define __noreturn __attribute__((noreturn)) |
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/* |
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* From the GCC manual: |
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* |
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* Many functions have no effects except the return value and their |
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* return value depends only on the parameters and/or global |
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* variables. Such a function can be subject to common subexpression |
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* elimination and loop optimization just as an arithmetic operator |
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* would be. |
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* [...] |
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*/ |
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#define __pure __attribute__((pure)) |
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#define __aligned(x) __attribute__((aligned(x))) |
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#define __aligned_largest __attribute__((aligned)) |
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#define __printf(a, b) __attribute__((format(printf, a, b))) |
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#define __scanf(a, b) __attribute__((format(scanf, a, b))) |
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#define __attribute_const__ __attribute__((__const__)) |
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#define __maybe_unused __attribute__((unused)) |
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#define __always_unused __attribute__((unused)) |
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#define __mode(x) __attribute__((mode(x))) |
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/* gcc version specific checks */ |
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#if GCC_VERSION < 30200 |
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# error Sorry, your compiler is too old - please upgrade it. |
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#endif |
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#if GCC_VERSION < 30300 |
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# define __used __attribute__((__unused__)) |
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#else |
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# define __used __attribute__((__used__)) |
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#endif |
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#ifdef CONFIG_GCOV_KERNEL |
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# if GCC_VERSION < 30400 |
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# error "GCOV profiling support for gcc versions below 3.4 not included" |
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# endif /* __GNUC_MINOR__ */ |
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#endif /* CONFIG_GCOV_KERNEL */ |
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#if GCC_VERSION >= 30400 |
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#define __must_check __attribute__((warn_unused_result)) |
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#define __malloc __attribute__((__malloc__)) |
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#endif |
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#if GCC_VERSION >= 40000 |
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/* GCC 4.1.[01] miscompiles __weak */ |
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#ifdef __KERNEL__ |
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# if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 |
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# error Your version of gcc miscompiles the __weak directive |
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# endif |
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#endif |
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#define __used __attribute__((__used__)) |
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#define __compiler_offsetof(a, b) \ |
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__builtin_offsetof(a, b) |
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#if GCC_VERSION >= 40100 |
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# define __compiletime_object_size(obj) __builtin_object_size(obj, 0) |
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#endif |
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#if GCC_VERSION >= 40300 |
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/* Mark functions as cold. gcc will assume any path leading to a call |
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* to them will be unlikely. This means a lot of manual unlikely()s |
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* are unnecessary now for any paths leading to the usual suspects |
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* like BUG(), printk(), panic() etc. [but let's keep them for now for |
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* older compilers] |
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* |
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* Early snapshots of gcc 4.3 don't support this and we can't detect this |
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* in the preprocessor, but we can live with this because they're unreleased. |
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* Maketime probing would be overkill here. |
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* |
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* gcc also has a __attribute__((__hot__)) to move hot functions into |
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* a special section, but I don't see any sense in this right now in |
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* the kernel context |
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*/ |
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#define __cold __attribute__((__cold__)) |
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#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) |
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#ifndef __CHECKER__ |
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# define __compiletime_warning(message) __attribute__((warning(message))) |
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# define __compiletime_error(message) __attribute__((error(message))) |
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#endif /* __CHECKER__ */ |
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#endif /* GCC_VERSION >= 40300 */ |
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#if GCC_VERSION >= 40400 |
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#define __optimize(level) __attribute__((__optimize__(level))) |
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#define __nostackprotector __optimize("no-stack-protector") |
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#endif /* GCC_VERSION >= 40400 */ |
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#if GCC_VERSION >= 40500 |
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#ifndef __CHECKER__ |
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#ifdef LATENT_ENTROPY_PLUGIN |
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#define __latent_entropy __attribute__((latent_entropy)) |
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#endif |
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#endif |
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/* |
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* calling noreturn functions, __builtin_unreachable() and __builtin_trap() |
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* confuse the stack allocation in gcc, leading to overly large stack |
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* frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 |
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* |
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* Adding an empty inline assembly before it works around the problem |
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*/ |
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#define barrier_before_unreachable() asm volatile("") |
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/* |
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* Mark a position in code as unreachable. This can be used to |
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* suppress control flow warnings after asm blocks that transfer |
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* control elsewhere. |
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* |
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* Early snapshots of gcc 4.5 don't support this and we can't detect |
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* this in the preprocessor, but we can live with this because they're |
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* unreleased. Really, we need to have autoconf for the kernel. |
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*/ |
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#define unreachable() \ |
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do { \ |
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annotate_unreachable(); \ |
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barrier_before_unreachable(); \ |
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__builtin_unreachable(); \ |
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} while (0) |
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/* Mark a function definition as prohibited from being cloned. */ |
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#define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) |
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#ifdef RANDSTRUCT_PLUGIN |
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#define __randomize_layout __attribute__((randomize_layout)) |
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#define __no_randomize_layout __attribute__((no_randomize_layout)) |
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/* This anon struct can add padding, so only enable it under randstruct. */ |
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#define randomized_struct_fields_start struct { |
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#define randomized_struct_fields_end } __randomize_layout; |
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#endif |
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#endif /* GCC_VERSION >= 40500 */ |
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#if GCC_VERSION >= 40600 |
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/* |
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* When used with Link Time Optimization, gcc can optimize away C functions or |
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* variables which are referenced only from assembly code. __visible tells the |
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* optimizer that something else uses this function or variable, thus preventing |
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* this. |
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*/ |
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#define __visible __attribute__((externally_visible)) |
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#endif /* GCC_VERSION >= 40600 */ |
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#if GCC_VERSION >= 40900 && !defined(__CHECKER__) |
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/* |
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* __assume_aligned(n, k): Tell the optimizer that the returned |
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* pointer can be assumed to be k modulo n. The second argument is |
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* optional (default 0), so we use a variadic macro to make the |
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* shorthand. |
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* |
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* Beware: Do not apply this to functions which may return |
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* ERR_PTRs. Also, it is probably unwise to apply it to functions |
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* returning extra information in the low bits (but in that case the |
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* compiler should see some alignment anyway, when the return value is |
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* massaged by 'flags = ptr & 3; ptr &= ~3;'). |
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*/ |
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#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) |
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#endif |
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/* |
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* GCC 'asm goto' miscompiles certain code sequences: |
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* |
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* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 |
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* |
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* Work it around via a compiler barrier quirk suggested by Jakub Jelinek. |
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* |
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* (asm goto is automatically volatile - the naming reflects this.) |
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*/ |
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#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) |
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/* |
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* sparse (__CHECKER__) pretends to be gcc, but can't do constant |
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* folding in __builtin_bswap*() (yet), so don't set these for it. |
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*/ |
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#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__) |
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#if GCC_VERSION >= 40400 |
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#define __HAVE_BUILTIN_BSWAP32__ |
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#define __HAVE_BUILTIN_BSWAP64__ |
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#endif |
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#if GCC_VERSION >= 40800 |
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#define __HAVE_BUILTIN_BSWAP16__ |
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#endif |
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#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */ |
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#if GCC_VERSION >= 70000 |
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#define KASAN_ABI_VERSION 5 |
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#elif GCC_VERSION >= 50000 |
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#define KASAN_ABI_VERSION 4 |
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#elif GCC_VERSION >= 40902 |
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#define KASAN_ABI_VERSION 3 |
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#endif |
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#if GCC_VERSION >= 40902 |
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/* |
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* Tell the compiler that address safety instrumentation (KASAN) |
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* should not be applied to that function. |
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* Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 |
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*/ |
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#define __no_sanitize_address __attribute__((no_sanitize_address)) |
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#endif |
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#if GCC_VERSION >= 50100 |
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/* |
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* Mark structures as requiring designated initializers. |
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* https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html |
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*/ |
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#define __designated_init __attribute__((designated_init)) |
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#endif |
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#if GCC_VERSION >= 90100 |
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#define __copy(symbol) __attribute__((__copy__(symbol))) |
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#endif |
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#endif /* gcc version >= 40000 specific checks */ |
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#if !defined(__noclone) |
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#define __noclone /* not needed */ |
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#endif |
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#if !defined(__no_sanitize_address) |
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#define __no_sanitize_address |
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#endif |
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/* |
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* A trick to suppress uninitialized variable warning without generating any |
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* code |
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*/ |
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#define uninitialized_var(x) x = x |
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#if GCC_VERSION >= 50100 |
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#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 |
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#endif
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