| #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 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)); \ |
| }) |
| |
| /* 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) |
| |
| #define __nostackprotector __attribute__((__optimize__("no-stack-protector"))) |
| #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 |
| |
| /* |
| * 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 */ |
| |
| |
| #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 |