forked from mirrors/linux
9c695203a7
A __naked function is defined in C but with a body completely implemented by asm(), including any prologue and epilogue. These asm() bodies expect standard calling conventions for parameter passing. Older GCCs implement that correctly, but 4.[56] currently do not, see GCC PR44290. In the Linux kernel this breaks ARM, causing most arch/arm/mm/copypage-*.c modules to get miscompiled, resulting in kernel crashes during bootup. Part of the kernel fix is to augment the __naked function attribute to also imply noinline and noclone. This patch implements that, and has been verified to fix boot failures with gcc-4.5 compiled 2.6.34 and 2.6.35-rc1 kernels. The patch is a no-op with older GCCs. Signed-off-by: Mikael Pettersson <mikpe@it.uu.se> Signed-off-by: Khem Raj <raj.khem@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
65 lines
2.2 KiB
C
65 lines
2.2 KiB
C
#ifndef __LINUX_COMPILER_H
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#error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead."
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#endif
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/* GCC 4.1.[01] miscompiles __weak */
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#ifdef __KERNEL__
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# if __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ <= 1
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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 __must_check __attribute__((warn_unused_result))
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#define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
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#define __always_inline inline __attribute__((always_inline))
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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 __GNUC_MINOR__ >= 3
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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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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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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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#define __cold __attribute__((__cold__))
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#if __GNUC_MINOR__ >= 5
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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() __builtin_unreachable()
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/* Mark a function definition as prohibited from being cloned. */
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#define __noclone __attribute__((__noclone__))
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#endif
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#endif
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#if __GNUC_MINOR__ > 0
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#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
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#endif
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#if __GNUC_MINOR__ >= 4
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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
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