815f0ddb34
Commitcafa0010cd("Raise the minimum required gcc version to 4.6") recently exposed a brittle part of the build for supporting non-gcc compilers. Both Clang and ICC define __GNUC__, __GNUC_MINOR__, and __GNUC_PATCHLEVEL__ for quick compatibility with code bases that haven't added compiler specific checks for __clang__ or __INTEL_COMPILER. This is brittle, as they happened to get compatibility by posing as a certain version of GCC. This broke when upgrading the minimal version of GCC required to build the kernel, to a version above what ICC and Clang claim to be. Rather than always including compiler-gcc.h then undefining or redefining macros in compiler-intel.h or compiler-clang.h, let's separate out the compiler specific macro definitions into mutually exclusive headers, do more proper compiler detection, and keep shared definitions in compiler_types.h. Fixes:cafa0010cd("Raise the minimum required gcc version to 4.6") Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com> Suggested-by: Eli Friedman <efriedma@codeaurora.org> Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
250 lines
8.3 KiB
C
250 lines
8.3 KiB
C
/* 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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#if GCC_VERSION < 40600
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# error Sorry, your compiler is too old - please upgrade it.
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#endif
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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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/*
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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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#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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#ifdef 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 __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
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#define __optimize(level) __attribute__((__optimize__(level)))
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#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
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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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#ifdef LATENT_ENTROPY_PLUGIN
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#define __latent_entropy __attribute__((latent_entropy))
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#endif
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#endif /* __CHECKER__ */
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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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#if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
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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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/*
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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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/* gcc version specific checks */
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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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#define __HAVE_BUILTIN_BSWAP32__
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#define __HAVE_BUILTIN_BSWAP64__
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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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#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
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#endif
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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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* Turn individual warnings and errors on and off locally, depending
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* on version.
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*/
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#define __diag_GCC(version, severity, s) \
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__diag_GCC_ ## version(__diag_GCC_ ## severity s)
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/* Severity used in pragma directives */
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#define __diag_GCC_ignore ignored
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#define __diag_GCC_warn warning
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#define __diag_GCC_error error
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#define __diag_str1(s) #s
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#define __diag_str(s) __diag_str1(s)
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#define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
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#if GCC_VERSION >= 80000
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#define __diag_GCC_8(s) __diag(s)
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#else
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#define __diag_GCC_8(s)
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#endif
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