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JoePerchestorvalds
JoePerches
authored and
torvalds
committed
Raise the minimum required gcc version to 4.6
Various architectures fail to build properly with older versions of the gcc compiler. An example from Guenter Roeck in thread [1]: > > In file included from ./include/linux/mm.h:17:0, > from ./include/linux/pid_namespace.h:7, > from ./include/linux/ptrace.h:10, > from arch/openrisc/kernel/asm-offsets.c:32: > ./include/linux/mm_types.h:497:16: error: flexible array member in otherwise empty struct > > This is just an example with gcc 4.5.1 for or32. I have seen the problem > with gcc 4.4 (for unicore32) as well. So update the minimum required version of gcc to 4.6. [1] https://lore.kernel.org/lkml/20180814170904.GA12768@roeck-us.net/ Miscellanea: - Update Documentation/process/changes.rst - Remove and consolidate version test blocks in compiler-gcc.h for versions lower than 4.6 Signed-off-by: Joe Perches <joe@perches.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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‎Documentation/process/changes.rst

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@@ -29,7 +29,7 @@ you probably needn't concern yourself with isdn4k-utils.
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====================== =============== ========================================
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Program Minimal version Command to check the version
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====================== =============== ========================================
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GNU C 3.2 gcc --version
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GNU C 4.6 gcc --version
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GNU make 3.81 make --version
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binutils 2.20 ld -v
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flex 2.5.35 flex --version

‎include/linux/compiler-gcc.h

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@@ -10,6 +10,10 @@
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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 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 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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!defined(CONFIG_OPTIMIZE_INLINING)
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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 __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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#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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#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
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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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#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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*/
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#define __visible __attribute__((externally_visible))
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#endif /* GCC_VERSION >= 40600 */
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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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* 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
@@ -340,10 +304,9 @@
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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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#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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#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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/*
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* Turn individual warnings and errors on and off locally, depending
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* on version.
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#define __diag_GCC_warn warning
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#define __diag_GCC_error error
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/* Compilers before gcc-4.6 do not understand "#pragma GCC diagnostic push" */
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#if GCC_VERSION >= 40600
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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))
382-
#endif
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#if GCC_VERSION >= 80000
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#define __diag_GCC_8(s) __diag(s)

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