I have started to look a little bit at the LTP tests.
And one of the testcases that fails (actually it doesn't fail as it
supposed to do) is the syscall getsockopt.
I think the failure is due to the copy_to_user(0, from, 4) call returns
0, which I wouldn't expect when the destination pointer is NULL.
I think the problem is in the __copy_user function in
It tries to handle the exception, which we get because the destination
pointer is NULL, by returning the number of uncopied bytes in $a2 to the
But in this case the length is only 4 bytes, and the copying is done by
a single 'sw'. The problem is the length ($a2) is decreased by 4 before
the 'sw' is executed.
The 'sw' fails and __copy_user terminates, but returns with $a2 = 0
I thing the following patch will solve the problem.
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RCS file: /home/repository/sw/linux-2.4.18/arch/mips/lib/memcpy.S,v
retrieving revision 126.96.36.199
diff -u -r188.8.131.52 memcpy.S
--- arch/mips/lib/memcpy.S 4 Mar 2002 11:12:21 -0000 184.108.40.206
+++ arch/mips/lib/memcpy.S 24 Jun 2002 13:46:07 -0000
@@ -248,8 +248,8 @@
EXC( LOAD t0, 0(src), l_exc)
ADD src, src, NBYTES
- SUB len, len, NBYTES
EXC( STORE t0, 0(dst), s_exc)
+ SUB len, len, NBYTES
bne rem, len, 1b
ADD dst, dst, NBYTES