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SubjectRe: [GIT PULL 00/66] perf/core improvements and fixes
Em Wed, Jul 13, 2016 at 10:54:49PM +0200, Peter Zijlstra escreveu:
> On Wed, Jul 13, 2016 at 03:49:14PM -0500, Josh Poimboeuf wrote:
> > That '#define BITS_PER_LONG 32' comes from the following code in
> > tools/include/asm-generic/bitsperlong.h:
> >
> > #ifdef CONFIG_64BIT
> > #define BITS_PER_LONG 64
> > #else
> > #define BITS_PER_LONG 32
> > #endif /* CONFIG_64BIT */
> >
> > Because objtool doesn't have CONFIG_64BIT defined, it falls through to
> > the '#else' condition. I think tools code shouldn't be relying on
> > kernel config options.
>
> Right.. __LP64__ would work in general I think, or __SIZEOF_LONG__ *
> __CHAR_BIT__.

Ok, to keep it close to the kernel counterpart, I ended up with the
patch below, that builds for all the distros I have in my container set.

commit 2a00f026a15d161b47ba3d3417d0fec5193468c3
Author: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Wed Jul 13 15:04:04 2016 -0300

tools: Fix up BITS_PER_LONG setting

It was set based on CONFIG_64BIT, that is available only when using
Kconfig, which we're working towards but not to the point of having this
CONFIG variable set, so synthesize it from available compiler defined
defines, __SIZEOF_LONG__ or, lacking that, __WORDSIZE.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-og5fmkr17856lhupacihwxvb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/include/asm-generic/bitsperlong.h b/tools/include/asm-generic/bitsperlong.h
index d1d70aa19021..cfd661c6fc17 100644
--- a/tools/include/asm-generic/bitsperlong.h
+++ b/tools/include/asm-generic/bitsperlong.h
@@ -3,6 +3,24 @@

#include <uapi/asm-generic/bitsperlong.h>

+/*
+ * In the kernel, where this file comes from, we can rely on CONFIG_64BIT,
+ * here we have to make amends with what the various compilers provides us
+ * to figure out if we're on a 64-bit machine...
+ */
+#ifdef __SIZEOF_LONG__
+# if __SIZEOF_LONG__ == 8
+# define CONFIG_64BIT
+# endif
+#else
+# ifdef __WORDSIZE
+# if __WORDSIZE == 64
+# define CONFIG_64BIT
+# endif
+# else
+# error Failed to determine BITS_PER_LONG value
+# endif
+#endif

#ifdef CONFIG_64BIT
#define BITS_PER_LONG 64
@@ -10,11 +28,7 @@
#define BITS_PER_LONG 32
#endif /* CONFIG_64BIT */

-/*
- * FIXME: The check currently breaks x86-64 build, so it's
- * temporarily disabled. Please fix x86-64 and reenable
- */
-#if 0 && BITS_PER_LONG != __BITS_PER_LONG
+#if BITS_PER_LONG != __BITS_PER_LONG
#error Inconsistent word size. Check asm/bitsperlong.h
#endif

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