Re: port-powerpc/39257: Mistake in sys/arch/powerpc/powerpc/trap_subr.S file

[Konrad Karpowicz <konradk%pacomp.pl@localhost>]

The following reply was made to PR port-powerpc/39257; it has been noted by 
GNATS.

From: Konrad Karpowicz <konradk%pacomp.pl@localhost>
To: Havard Eidnes <he%NetBSD.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost, 
port-powerpc-maintainer%netbsd.org@localhost, 
 gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
konstrukcja%pacomp.pl@localhost
Subject: Re: port-powerpc/39257: Mistake in sys/arch/powerpc/powerpc/trap_subr.S
 file
Date: Fri, 01 Aug 2008 14:23:29 +0200

 Havard Eidnes pisze:
 >> Tim Rightnour pisze:
 >>     
 >>>  I looked at the file at the location you mentioned, but I don't
 >>>  think the current code in CVS matches whatever you are looking
 >>>  at.  The line numbers you gave don't match up.  Can you please
 >>>  either tell me what the CVS revision number at the top of the
 >>>  file you are looking at is, or look at the most current one,
 >>>  which is
 >>>       
 >> Dear Tim,
 >> Thank you very much for quick answer. You are right, I was looking at 
 >> trap_subr.S v1.59.
 >> In v 1.64 the line numbers are 540-547.
 >> Lines 540 and 541: in my opinion the contents of R1 are not used anymore.
 >> Line 544: change of the contents of R2 results in incorrect value loaded 
 >> into R1 in line 547.
 >>     
 >
 > It would probably be helpful if you quoted the actual code and gave
 > a bit more context, such as which function you are talking about.
 > The reason I say this is that in revision 1.64 of trap_subr.S, lines
 > 540-547 look as follows:
 >
 > #endif
 > _C_LABEL(tlbdlmsize) = .-_C_LABEL(tlbdlmiss)
 >
 > /* LINTSTUB: Var: int tlbdsmiss[1], tlbdsmsize[1]; */
 >         .globl  _C_LABEL(tlbdsmiss),_C_LABEL(tlbdsmsize)
 > _C_LABEL(tlbdsmiss):
 >         mfspr   %r2,SPR_HASH1           /* get first pointer */
 >         li      %r1,%r8
 >
 > which is probably not what you wanted to indicate.
 >
 > Regards,
 >
 > - Havard
 Dear Havard,
 
 Sorry again. German NetBSD FTP server has out of date NetBSD-current.
 The lines are 590-597:
 
     mfspr    %r3,SPR_DMISS        /* get the miss address */
     mfsrin    %r1,%r3            /* get the segment register */
     mfsrr1    %r3
     rlwinm    %r3,%r3,18,31,31    /* get PR-bit */
     rlwnm.    %r2,%r2,%r3,1,1        /* get the key */
     bne-    9b            /* protection violation */
 8:    /* found, set reference/change bits */
     ldreg    %r1,4(%r2)        /* reload tlb entry */
 
 At the moment I know which line has a bug. It is line
 rlwnm.    %r2,%r2,%r3,1,1        /* get the key */
 and it should be:
 rlwnm.    %r1,%r1,%r3,1,1        /* get the key */
 
 Now it seems to work OK. How is it possible that you haven't noticed it 
 before?
 
 Kind regards,
 Konrad Karpowicz
 PACOMP