From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030202AbXDDDV0 (ORCPT ); Tue, 3 Apr 2007 23:21:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030258AbXDDDV0 (ORCPT ); Tue, 3 Apr 2007 23:21:26 -0400 Received: from agminet01.oracle.com ([141.146.126.228]:21706 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030202AbXDDDVZ (ORCPT ); Tue, 3 Apr 2007 23:21:25 -0400 Date: Tue, 3 Apr 2007 20:22:40 -0700 From: Randy Dunlap To: Rusty Russell Cc: lkml - Kernel Mailing List , Andrew Morton Subject: Re: [PATCH] Expose range-checking functions from arch-specific uaccess.h Message-Id: <20070403202240.f212954b.randy.dunlap@oracle.com> In-Reply-To: <1175653718.12230.566.camel@localhost.localdomain> References: <1175653718.12230.566.camel@localhost.localdomain> Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.3.1 (GTK+ 2.8.10; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Whitelist: TRUE X-Whitelist: TRUE X-Brightmail-Tracker: AAAAAQAAAAI= Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 04 Apr 2007 12:28:38 +1000 Rusty Russell wrote: > lguest wants range checking, but unless there are other users I'm not > sure this is worth the pain. Putting it out there in case it's useful. > > Cheers, > Rusty. > == > There are some places where we want to check if a value + length is > within a range. This can be tricky, so it's nice to have a single > routine. > > Also, this can be done more efficiently (with arch-dependent) carry > bits, as shown by the __range_ok() implementation on several archs. > > This patch exposes arch-specific "val_outside(val, len, limit)" and a > generic "range_within(start, len, base, limit)" function. As a > side-effect, it fixes the comment in i386/uaccess.h: __range_ok > doesn't test "(u33)addr + (u33)size >= (u33)current->addr_limit.seg", > it tests "(u33)addr + (u33)size > (u33)current->addr_limit.seg". > > Signed-off-by: Rusty Russell > > diff -r 4272a6d4f27c include/asm-generic/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-generic/range.h Wed Apr 04 12:18:15 2007 +1000 > @@ -0,0 +1,20 @@ > +#ifndef _ASM_GENERIC_RANGE_H > +#define _ASM_GENERIC_RANGE_H > + > +/** > + * val_outside - is a value and length past a limit? > + * @val: the start value > + * @len: the length from the start > + * @limit: the first invalid value > + * > + * Like val + len > limit, except with overflow checking. > + */ > +static inline bool val_outside(unsigned long val, unsigned long len, > + unsigned long limit) > + > +{ > + return val + len > limit || val + len < val; why isn't that return val + len >= limit || val + len < val; > +} > + > +#endif /* _ASM_GENERIC_RANGE_H */ > + > diff -r 4272a6d4f27c include/asm-i386/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-i386/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,14 @@ > +#ifndef __ASM_RANGE_H > +#define __ASM_RANGE_H > + > +/* Is val + size > limit? This needs 33-bit arithmetic. We have a carry... */ > +static inline bool val_outside(unsigned long val, unsigned long len, > + unsigned long limit) > +{ > + unsigned long flag, roksum; > + asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" > + :"=&r" (flag), "=r" (roksum) > + :"1" (val), "g" (len), "rm" (limit)); > + return flag; > +} > +#endif /* __ASM_RANGE_H */ > diff -r 4272a6d4f27c include/asm-i386/uaccess.h > --- a/include/asm-i386/uaccess.h Wed Apr 04 12:05:49 2007 +1000 > +++ b/include/asm-i386/uaccess.h Wed Apr 04 12:14:45 2007 +1000 > @@ -49,17 +49,12 @@ extern struct movsl_mask { > * Returns 0 if the range is valid, nonzero otherwise. > * > * This is equivalent to the following test: > - * (u33)addr + (u33)size >= (u33)current->addr_limit.seg > - * > - * This needs 33-bit arithmetic. We have a carry... > - */ > -#define __range_ok(addr,size) ({ \ > - unsigned long flag,roksum; \ > - __chk_user_ptr(addr); \ > - asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \ > - :"=&r" (flag), "=r" (roksum) \ > - :"1" (addr),"g" ((int)(size)),"rm" (current_thread_info()->addr_limit.seg)); \ > - flag; }) > + * (u33)addr + (u33)size > (u33)current->addr_limit.seg > + */ > +#define __range_ok(addr,size) ({ \ > + __chk_user_ptr(addr); \ > + val_outside((int)(addr),(size),current_thread_info()->addr_limit.seg); \ space after commas, please. > +}) > > /** > * access_ok: - Checks if a user space pointer is valid > diff -r 4272a6d4f27c include/linux/kernel.h > --- a/include/linux/kernel.h Wed Apr 04 12:05:49 2007 +1000 > +++ b/include/linux/kernel.h Wed Apr 04 12:22:52 2007 +1000 > @@ -16,6 +16,7 @@ > #include > #include > #include > +#include > > extern const char linux_banner[]; > extern const char linux_proc_banner[]; > @@ -311,6 +312,26 @@ static inline int __attribute__ ((format > (void)__tmp; \ > }) > > +/** > + * range_within - is one range within another? > + * @start: the start value > + * @len: the length from the start > + * @base: the first valid value > + * @limit: the first invalid value > + * > + * This is usually used for memory range testing. The common cases of > + * constant 0 start and constant 0 len cases are optimized out. > + */ Where is constant 0 start optimized out? > +static inline bool range_within(unsigned long start, unsigned long len, > + unsigned long base, unsigned long limit) > +{ > + if (start < base) > + return false; > + if (__builtin_constant_p(len) && len == 0) I don't see what the builtin_constant_p() adds here. If len == 0, this return is still OK, isn't it? > + return start - base <= limit - base; > + return !val_outside(limit, start, len); > +} > + > struct sysinfo; > extern int do_sysinfo(struct sysinfo *info); > > diff -r 4272a6d4f27c include/asm-alpha/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-alpha/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-arm/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-arm/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H why ALPHA ? > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-arm26/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-arm26/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H ditto > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-avr32/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-avr32/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H tritto etc. etc. > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-blackfin/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-blackfin/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-cris/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-cris/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-frv/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-frv/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-h8300/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-h8300/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-ia64/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-ia64/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-m32r/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-m32r/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-m68k/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-m68k/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-m68knommu/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-m68knommu/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-mips/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-mips/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-parisc/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-parisc/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-powerpc/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-powerpc/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-ppc/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-ppc/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-s390/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-s390/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-sh/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-sh/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-sh64/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-sh64/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-sparc/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-sparc/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-sparc64/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-sparc64/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-um/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-um/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-v850/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-v850/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-x86_64/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-x86_64/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ > diff -r 4272a6d4f27c include/asm-xtensa/range.h > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/include/asm-xtensa/range.h Wed Apr 04 12:14:45 2007 +1000 > @@ -0,0 +1,6 @@ > +#ifndef __ALPHA_RANGE_H > +#define __ALPHA_RANGE_H > + > +#include > + > +#endif /* __ALPHA_RANGE_H */ --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***