[uClibc 0005464]: Memcpy forward copy breaks with unaligned transfers in memcpy(ARM)
bugs at busybox.net
bugs at busybox.net
Fri Oct 17 13:05:58 UTC 2008
A NOTE has been added to this issue.
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http://busybox.net/bugs/view.php?id=5464
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Reported By: upakul
Assigned To: uClibc
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Project: uClibc
Issue ID: 5464
Category: Architecture Specific
Reproducibility: always
Severity: minor
Priority: normal
Status: assigned
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Date Submitted: 10-17-2008 05:26 PDT
Last Modified: 10-17-2008 06:05 PDT
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Summary: 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];]
======================================================================
----------------------------------------------------------------------
bernhardf - 10-17-08 05:41
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You need to specify which version of uClibc you are using.
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upakul - 10-17-08 06:00
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uClibc version used is 0.9.29
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bernhardf - 10-17-08 06:05
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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
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
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