0005464: Memcpy forward copy breaks with unaligned transfers in memcpy(ARM)

BusyBox Bug and Patch Tracking

Viewing Issue Simple Details [ Jump to Notes ]

[ View Advanced ] [ Issue History ] [ Print ]

Category

Severity

Reproducibility

Date Submitted

Last Update

0005464

[uClibc] Architecture Specific

minor

always

10-17-08 05:26

10-20-08 00:54

Reporter

upakul

View Status

public

Assigned To

uClibc

Priority

normal

Resolution

fixed

Status

closed

Product Version

0.9.27

Summary

0005464: Memcpy forward copy breaks with unaligned transfers in memcpy(ARM)

Description

Hi all,

The issue observed is that if we try to do unaligned transfers in the case of forward copy it raises an error. However everything works fine in the case of backward copy.

To reproduce write a simple program like:

#include <stdio.h>
#include <string.h>
#include <sys/time.h>

static volatile char dst[4*1024*1024+64],src[4*1024*1024+64];

int main(int argc, char **argv)
{
   int i, count=atoi(argv[2]);
   char *newsrc = (char *)( ( ( ((int)&src[31])/32 )*32) + atoi(argv[1]));
   char *newdst = (char *)( ( ( ((int)&dst[31])/32 )*32) + atoi(argv[1]));
   memset(newsrc,'A',4194304);
   memset(newdst,'B',4194304);
   for (i=0;i<count;i++)
   {
     memcpy(newdst, newsrc, 4194304);
   }
   return 0;
}

Where argv[1] is the alignment. It will throw error if alignment is 1,3 and so on... However the same thing works fine in the case of backward copy[To perform a backward copy, declare the buffers as static volatile char src[4*1024*1024+64], dst[4*1024*1024+64];]

Additional Information

Attached Files

Relationships

Notes
(0013724) bernhardf 10-17-08 05:41	You need to specify which version of uClibc you are using.

(0013734) upakul 10-17-08 05:52 edited on: 10-17-08 06:00	uClibc version used is 0.9.29

(0013744) bernhardf 10-17-08 06:05	ISTR that there were fixes in this area (0.9.27 is very old). Try a recent version, I'd recommend to use trunk which will be released as 0.9.30 soon: $ svn co svn://uclibc.org/trunk/uClibc [^]

(0013854) upakul 10-19-08 21:37	The issue is not visible with the latest version. Thanks.

Issue History
Date Modified	Username	Field	Change
10-17-08 05:26	upakul	New Issue
10-17-08 05:26	upakul	Status	new => assigned
10-17-08 05:26	upakul	Assigned To	=> uClibc
10-17-08 05:41	bernhardf	Note Added: 0013724
10-17-08 05:52	upakul	Note Added: 0013734
10-17-08 06:00	upakul	Note Edited: 0013734
10-17-08 06:05	bernhardf	Note Added: 0013744
10-17-08 06:06	bernhardf	version	=> 0.9.27
10-19-08 21:37	upakul	Note Added: 0013854
10-20-08 00:54	bernhardf	Status	assigned => closed
10-20-08 00:54	bernhardf	Resolution	open => fixed
10-20-08 00:54	bernhardf	Fixed in Version	=> 0.9.30