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 > > > with a known size for the source string to be replaced with memcpy which > > > is faster. ia64 memcpy has return values which are unlike stdlibc and > > > the other arch memcpy routines examined by me in the kernel. The ia64 return > > > values are 0 for success and number of bytes copied for failure. Thus any > > > instance of pointer = strcpy(dest, "some string") has zero assigned to > > > pointer. I detected this when testing kgdb on 2.6.17-rc3. > > > > > > The implementation in memcpy_mck.S doesn't leave a single scratch > > > register or predicate. I didn't pursue very long for a solution. > > > > I thought I fixed that about 3 years ago: > > > > http://marc.theaimsgroup.com/?l=linux-ia64&m=105590709805435&w=2 > > > > Did it fall through the crack? I'm not sure what's going on. > > It looks to have definitely fallen through a crack or two. > > I applied to rc3 and boot tested for you. I assume you'll post patch again. 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 <kenneth.w.chen@xxxxxxxxx> --- ./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 <kenneth.w.chen@xxxxxxxxx> @@ -73,6 +75,7 @@ GLOBAL_ENTRY(memcpy) and r28=0x7,in0 and r29=0x7,in1 mov f6=f0 + mov retval=in0 br.cond.sptk .common_code ;; END(memcpy) @@ -84,7 +87,7 @@ GLOBAL_ENTRY(__copy_user) mov f6=f1 mov saved_in0=in0 // save dest pointer mov saved_in1=in1 // save src pointer - mov saved_in2=in2 // save len + mov retval=r0 // initialize return value ;; .common_code: cmp.gt p15,p0=8,in2 // check for small size @@ -92,7 +95,7 @@ GLOBAL_ENTRY(__copy_user) cmp.ne p14,p0=0,r29 // check src alignment add src0=0,in1 sub r30=8,r28 // for .align_dest - mov retval=r0 // initialize return value + mov saved_in2=in2 // save len ;; add dst0=0,in0 add dst1=1,in0 // dest odd index - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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