From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Wed, 03 May 2006 18:46:07 +0000 Subject: RE: strcpy returns NULL pointer and not destination pointer Message-Id: <4t16i2$tj9fu@orsmga001.jf.intel.com> List-Id: References: <20060503133806.GC19859@localhost> In-Reply-To: <20060503133806.GC19859@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: linux-ia64@vger.kernel.org Bob Picco wrote on Wednesday, May 03, 2006 11:31 AM > Chen, Kenneth W wrote: [Wed May 03 2006, 02:08:47PM EDT] > > Bob Picco wrote on Wednesday, May 03, 2006 6:38 AM > > > The removal of -ffreestanding compiler flag in 2.6.17-rcX (commit id > > > 6edfba1b33c701108717f4e036320fc39abe1912) causes strcpy calls=20 > > > with a known size for the source string to be replaced with memcpy wh= ich > > > is faster. ia64 memcpy has return values which are unlike stdlibc and > > > the other arch memcpy routines examined by me in the kernel. The ia6= 4 return > > > values are 0 for success and number of bytes copied for failure. Thus= any > > > instance of pointer =3D strcpy(dest, "some string") has zero assigned= to > > > pointer. I detected this when testing kgdb on 2.6.17-rc3. =20 > > >=20 > > > The implementation in memcpy_mck.S doesn't leave a single scratch > > > register or predicate. I didn't pursue very long for a solution. > >=20 > > I thought I fixed that about 3 years ago: > >=20 > > http://marc.theaimsgroup.com/?l=3Dlinux-ia64&m=105590709805435&w=3D2 > >=20 > > Did it fall through the crack? I'm not sure what's going on. >=20 > It looks to have definitely fallen through a crack or two. >=20 > I applied to rc3 and boot tested for you. I assume you'll post patch agai= n. Wow, 3 years ago patch still applies. I'm impressed, that doesn't happen very often ;-) Here is an updated version, with comments updated (bcopy was removed). [patch] fix return value of memcpy Signed-off-by: Ken Chen --- ./arch/ia64/lib/memcpy_mck.S.orig 2006-03-19 21:53:29.000000000 -0800 +++ ./arch/ia64/lib/memcpy_mck.S 2006-05-03 12:30:20.000000000 -0700 @@ -6,7 +6,9 @@ * in1: source address * in2: number of bytes to copy * Output: - * 0 if success, or number of byte NOT copied if error occurred. + * for memcpy: retrun dest + * for copy_user: return 0 if success, + * or number of byte NOT copied if error occurred. * * Copyright (C) 2002 Intel Corp. * Copyright (C) 2002 Ken Chen @@ -73,6 +75,7 @@ GLOBAL_ENTRY(memcpy) and r28=3D0x7,in0 and r29=3D0x7,in1 mov f6=F0 + mov retval=3Din0 br.cond.sptk .common_code ;; END(memcpy) @@ -84,7 +87,7 @@ GLOBAL_ENTRY(__copy_user) mov f6=F1 mov saved_in0=3Din0 // save dest pointer mov saved_in1=3Din1 // save src pointer - mov saved_in2=3Din2 // save len + mov retval=3Dr0 // initialize return value ;; .common_code: cmp.gt p15,p0=3D8,in2 // check for small size @@ -92,7 +95,7 @@ GLOBAL_ENTRY(__copy_user) cmp.ne p14,p0=3D0,r29 // check src alignment add src0=3D0,in1 sub r30=3D8,r28 // for .align_dest - mov retval=3Dr0 // initialize return value + mov saved_in2=3Din2 // save len ;; add dst0=3D0,in0 add dst1=3D1,in0 // dest odd index