forked from mirrors/linux
3f0116c323
Fengguang Wu, Oleg Nesterov and Peter Zijlstra tracked down a kernel crash to a GCC bug: GCC miscompiles certain 'asm goto' constructs, as outlined here: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 Implement a workaround suggested by Jakub Jelinek. Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com> Reported-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Suggested-by: Jakub Jelinek <jakub@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
92 lines
3.1 KiB
C
92 lines
3.1 KiB
C
#ifndef __LINUX_COMPILER_H
|
|
#error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead."
|
|
#endif
|
|
|
|
/* 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 __must_check __attribute__((warn_unused_result))
|
|
#define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
|
|
|
|
#if GCC_VERSION >= 40100 && GCC_VERSION < 40600
|
|
# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
|
|
#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
|
|
/*
|
|
* 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() __builtin_unreachable()
|
|
|
|
/* Mark a function definition as prohibited from being cloned. */
|
|
#define __noclone __attribute__((__noclone__))
|
|
|
|
#endif /* GCC_VERSION >= 40500 */
|
|
|
|
#if GCC_VERSION >= 40600
|
|
/*
|
|
* Tell the optimizer that something else uses this function or variable.
|
|
*/
|
|
#define __visible __attribute__((externally_visible))
|
|
#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.
|
|
* Fixed in GCC 4.8.2 and later versions.
|
|
*
|
|
* (asm goto is automatically volatile - the naming reflects this.)
|
|
*/
|
|
#if GCC_VERSION <= 40801
|
|
# define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
|
|
#else
|
|
# define asm_volatile_goto(x...) do { asm goto(x); } while (0)
|
|
#endif
|
|
|
|
#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
|
|
#if GCC_VERSION >= 40400
|
|
#define __HAVE_BUILTIN_BSWAP32__
|
|
#define __HAVE_BUILTIN_BSWAP64__
|
|
#endif
|
|
#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
|
|
#define __HAVE_BUILTIN_BSWAP16__
|
|
#endif
|
|
#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
|