Hi Rene,
Rene Nielsen wrote,
I have found a bug in
.../libc/string/generic/memmove.c, which is the one that
MIPS uses, since there's no specialized, optimized version for MIPS.
We're currently using uClibc v. 1.0.12, but I suspect the bug to be present in
earlier releases too.
Here's a snippet from memmove.c#memmove():
---------------------oOo---------------------
/* This test makes the forward copying code be used whenever possible.
Reduces the working set. */
if (dstp - srcp >= len) /* *Unsigned* compare! */
{
#ifndef __ARCH_HAS_BWD_MEMCPY__
/* Backward memcpy implementation cannot be used */
memcpy(dest, src, len);
#else
/* Copy from the beginning to the end. */
---------------------oOo---------------------
Given the name of the define (__ARCH_HAS_BWD_MEMCPY__) it sounds as when this is
defined, the architecture indeed has backward memcpy() support. But how come the
line is preceded by #ifndef and not #ifdef, when the code inside calls memcpy()?
Also, the first comment inside the #ifndef seems odd, since memcpy() indeed is called:
/* Backward memcpy implementation cannot be used */
Our SDK does not define __ARCH_HAS_BWD_MEMCPY__, so when memmove()
resorts to a simple memcpy() that does the wrong thing for overlapping regions,
our application fails with disastrous side-effects.
I have attached a patch that fixes this.
Please CC me in case of any inquiries/replies: rene.nielsen (at)
microsemi.com
You are right, there is no special MIPS version for memmove().
The __ARCH_HAS_BWD_MEMCPY__ symbols was added in 2008 by this
commit e4f55f33f69fce85099dd5936cc74856aa1b453d. I would rather say,
that a default memcpy is used and there was a change for MIPS
recently.
Can you either try 1.0.9 or revert
2636b17616a19d628c3dbc373ebae67ef6e2b1f6 from 1.0.14?
The change to add MIPSr6 support ported from glibc and submitted by
Steve Ellcey <sellcey(a)imgtec.com> seems to trigger a problem with
old kernels on MIPS32 systems. If you search the mailinglist we had
some reports in the past, but I still couldn't reproduce the issue
to report to Steve.
Can you create a small test program showing your problem?
Something for the included test-suite would be really great.
What MIPS system do you use? MIPS32r2? little or big endian?
hard or soft-float toolchain? Which kernel version?
thanks
Waldemar