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[PATCH] x86: uapi: Fix __BITS_PER_LONG for x32

Started byBen Hutchings <ben@decadent.org.uk>
First post2015-10-01 02:50 +0200
Last post2015-10-02 09:50 +0200
Articles 6 — 4 participants

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  [PATCH] x86: uapi: Fix __BITS_PER_LONG for x32 Ben Hutchings <ben@decadent.org.uk> - 2015-10-01 02:50 +0200
    Re: [PATCH] x86: uapi: Fix __BITS_PER_LONG for x32 Ingo Molnar <mingo@kernel.org> - 2015-10-01 10:30 +0200
      Re: [PATCH] x86: uapi: Fix __BITS_PER_LONG for x32 Brian Gerst <brgerst@gmail.com> - 2015-10-01 15:10 +0200
        Re: [PATCH] x86: uapi: Fix __BITS_PER_LONG for x32 Ben Hutchings <ben@decadent.org.uk> - 2015-10-01 23:00 +0200
          Re: [PATCH] x86: uapi: Fix __BITS_PER_LONG for x32 Ben Hutchings <ben@decadent.org.uk> - 2015-10-02 04:00 +0200
    [tip:x86/urgent] x86/headers/uapi:   Fix __BITS_PER_LONG value for x32 builds tip-bot for Ben Hutchings <tipbot@zytor.com> - 2015-10-02 09:50 +0200

#1236882 — [PATCH] x86: uapi: Fix __BITS_PER_LONG for x32

FromBen Hutchings <ben@decadent.org.uk>
Date2015-10-01 02:50 +0200
Subject[PATCH] x86: uapi: Fix __BITS_PER_LONG for x32
Message-ID<qeAel-4BU-3@gated-at.bofh.it>

[Multipart message — attachments visible in raw view] — view raw

On x32, gcc predefines __x86_64__ but long is only 32-bit.  Use
__ILP32__ to distinguish x32.

Fixes this compiler error in perf:

/«PKGBUILDDIR»/tools/include/asm-generic/bitops/__ffs.h: In function '__ffs':
/«PKGBUILDDIR»/tools/include/asm-generic/bitops/__ffs.h:19:8: error: right shift count >= width of type [-Werror=shift-count-overflow]
   word >>= 32;
        ^

This isn't sufficient to build perf for x32, though.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/x86/include/uapi/asm/bitsperlong.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/bitsperlong.h b/arch/x86/include/uapi/asm/bitsperlong.h
index b0ae1c4..217909b 100644
--- a/arch/x86/include/uapi/asm/bitsperlong.h
+++ b/arch/x86/include/uapi/asm/bitsperlong.h
@@ -1,7 +1,7 @@
 #ifndef __ASM_X86_BITSPERLONG_H
 #define __ASM_X86_BITSPERLONG_H
 
-#ifdef __x86_64__
+#if defined(__x86_64__) && !defined(__ILP32__)
 # define __BITS_PER_LONG 64
 #else
 # define __BITS_PER_LONG 32
-- 
Ben Hutchings
Knowledge is power.  France is bacon.

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#1237127

FromIngo Molnar <mingo@kernel.org>
Date2015-10-01 10:30 +0200
Message-ID<qeHpx-6S6-23@gated-at.bofh.it>
In reply to#1236882
* Ben Hutchings <ben@decadent.org.uk> wrote:

> diff --git a/arch/x86/include/uapi/asm/bitsperlong.h b/arch/x86/include/uapi/asm/bitsperlong.h
> index b0ae1c4..217909b 100644
> --- a/arch/x86/include/uapi/asm/bitsperlong.h
> +++ b/arch/x86/include/uapi/asm/bitsperlong.h
> @@ -1,7 +1,7 @@
>  #ifndef __ASM_X86_BITSPERLONG_H
>  #define __ASM_X86_BITSPERLONG_H
>  
> -#ifdef __x86_64__
> +#if defined(__x86_64__) && !defined(__ILP32__)
>  # define __BITS_PER_LONG 64

Can we write this as:

   #ifdef __ILP64__

?

Thanks,

	Ingo
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#1237417

FromBrian Gerst <brgerst@gmail.com>
Date2015-10-01 15:10 +0200
Message-ID<qeLMv-53B-33@gated-at.bofh.it>
In reply to#1237127
On Thu, Oct 1, 2015 at 4:23 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Ben Hutchings <ben@decadent.org.uk> wrote:
>
>> diff --git a/arch/x86/include/uapi/asm/bitsperlong.h b/arch/x86/include/uapi/asm/bitsperlong.h
>> index b0ae1c4..217909b 100644
>> --- a/arch/x86/include/uapi/asm/bitsperlong.h
>> +++ b/arch/x86/include/uapi/asm/bitsperlong.h
>> @@ -1,7 +1,7 @@
>>  #ifndef __ASM_X86_BITSPERLONG_H
>>  #define __ASM_X86_BITSPERLONG_H
>>
>> -#ifdef __x86_64__
>> +#if defined(__x86_64__) && !defined(__ILP32__)
>>  # define __BITS_PER_LONG 64
>
> Can we write this as:
>
>    #ifdef __ILP64__

Do all versions of gcc/clang define that, even if x32 isn't supported?

--
Brian Gerst
--
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#1237724

FromBen Hutchings <ben@decadent.org.uk>
Date2015-10-01 23:00 +0200
Message-ID<qeT7k-7th-7@gated-at.bofh.it>
In reply to#1237417

[Multipart message — attachments visible in raw view] — view raw

On Thu, 2015-10-01 at 09:02 -0400, Brian Gerst wrote:
> On Thu, Oct 1, 2015 at 4:23 AM, Ingo Molnar <mingo@kernel.org> wrote:
> > 
> > * Ben Hutchings <ben@decadent.org.uk> wrote:
> > 
> > > diff --git a/arch/x86/include/uapi/asm/bitsperlong.h
> > > b/arch/x86/include/uapi/asm/bitsperlong.h
> > > index b0ae1c4..217909b 100644
> > > --- a/arch/x86/include/uapi/asm/bitsperlong.h
> > > +++ b/arch/x86/include/uapi/asm/bitsperlong.h
> > > @@ -1,7 +1,7 @@
> > >  #ifndef __ASM_X86_BITSPERLONG_H
> > >  #define __ASM_X86_BITSPERLONG_H
> > > 
> > > -#ifdef __x86_64__
> > > +#if defined(__x86_64__) && !defined(__ILP32__)
> > >  # define __BITS_PER_LONG 64
> > 
> > Can we write this as:
> > 
> >    #ifdef __ILP64__

Assuming you meant __LP64__...

> Do all versions of gcc/clang define that, even if x32 isn't
> supported?

For gcc, it's been defined since 2003 (gcc 3.3):
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=0bdab2d89e28ca4dc84f8f0fafed85a4822bca49

For clang, it's been defined since before its first public release:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Targets.cpp?r1=38978&r2=38987&pathrev=161685

So gcc 3.1 and 3.2 didn't define it, but everything newer does.

Ben.

-- 
Ben Hutchings
Knowledge is power.  France is bacon.

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#1237878

FromBen Hutchings <ben@decadent.org.uk>
Date2015-10-02 04:00 +0200
Message-ID<qeXNE-5NS-3@gated-at.bofh.it>
In reply to#1237724

[Multipart message — attachments visible in raw view] — view raw

On Thu, 2015-10-01 at 21:54 +0100, Ben Hutchings wrote:
> On Thu, 2015-10-01 at 09:02 -0400, Brian Gerst wrote:
> > On Thu, Oct 1, 2015 at 4:23 AM, Ingo Molnar <mingo@kernel.org> wrote:
> > > 
> > > * Ben Hutchings <ben@decadent.org.uk> wrote:
> > > 
> > > > diff --git a/arch/x86/include/uapi/asm/bitsperlong.h
> > > > b/arch/x86/include/uapi/asm/bitsperlong.h
> > > > index b0ae1c4..217909b 100644
> > > > --- a/arch/x86/include/uapi/asm/bitsperlong.h
> > > > +++ b/arch/x86/include/uapi/asm/bitsperlong.h
> > > > @@ -1,7 +1,7 @@
> > > >  #ifndef __ASM_X86_BITSPERLONG_H
> > > >  #define __ASM_X86_BITSPERLONG_H
> > > > 
> > > > -#ifdef __x86_64__
> > > > +#if defined(__x86_64__) && !defined(__ILP32__)
> > > >  # define __BITS_PER_LONG 64
> > > 
> > > Can we write this as:
> > > 
> > >    #ifdef __ILP64__
> 
> Assuming you meant __LP64__...
> 
> > Do all versions of gcc/clang define that, even if x32 isn't
> > supported?
> 
> For gcc, it's been defined since 2003 (gcc 3.3):
> https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=0bdab2d89e28ca4dc84f8f0fafed85a4822bca49
> 
> For clang, it's been defined since before its first public release:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Targets.cpp?r1=38978&r2=38987&pathrev=161685
> 
> So gcc 3.1 and 3.2 didn't define it, but everything newer does.

As the kernel itself is supposed to still be compilable with gcc 3.2, I
think this means that my patch has the right condition.

Ben.

-- 
Ben Hutchings
When in doubt, use brute force. - Ken Thompson

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#1238024 — [tip:x86/urgent] x86/headers/uapi: Fix __BITS_PER_LONG value for x32 builds

Fromtip-bot for Ben Hutchings <tipbot@zytor.com>
Date2015-10-02 09:50 +0200
Subject[tip:x86/urgent] x86/headers/uapi: Fix __BITS_PER_LONG value for x32 builds
Message-ID<qf3gn-5mM-41@gated-at.bofh.it>
In reply to#1236882
Commit-ID:  f4b4aae1828855db761bf998ce37d3062b1d6446
Gitweb:     http://git.kernel.org/tip/f4b4aae1828855db761bf998ce37d3062b1d6446
Author:     Ben Hutchings <ben@decadent.org.uk>
AuthorDate: Thu, 1 Oct 2015 01:40:43 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 2 Oct 2015 09:43:21 +0200

x86/headers/uapi: Fix __BITS_PER_LONG value for x32 builds

On x32, gcc predefines __x86_64__ but long is only 32-bit.  Use
__ILP32__ to distinguish x32.

Fixes this compiler error in perf:

	tools/include/asm-generic/bitops/__ffs.h: In function '__ffs':
	tools/include/asm-generic/bitops/__ffs.h:19:8: error: right shift count >= width of type [-Werror=shift-count-overflow]
	  word >>= 32;
	       ^

This isn't sufficient to build perf for x32, though.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1443660043.2730.15.camel@decadent.org.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/uapi/asm/bitsperlong.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/bitsperlong.h b/arch/x86/include/uapi/asm/bitsperlong.h
index b0ae1c4..217909b 100644
--- a/arch/x86/include/uapi/asm/bitsperlong.h
+++ b/arch/x86/include/uapi/asm/bitsperlong.h
@@ -1,7 +1,7 @@
 #ifndef __ASM_X86_BITSPERLONG_H
 #define __ASM_X86_BITSPERLONG_H
 
-#ifdef __x86_64__
+#if defined(__x86_64__) && !defined(__ILP32__)
 # define __BITS_PER_LONG 64
 #else
 # define __BITS_PER_LONG 32
--
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