[Bug binutils/10924] Bug in objdump when disassembling raw armv4t binaries

[chris at seberino dot org]

------- Additional Comments From chris at seberino dot org  2009-11-14 23:38 
-------
Subject: Re:  Bug in objdump when disassembling raw
        armv4t binaries

On Wed, Nov 11, 2009 at 09:54:45AM -0000, nickc at redhat dot com wrote:
> I have checked the patch in, but I will leave this issue open for reports of
> other UNPREDICTABLE bit patterns.

Nick

OK I tried to find all bugs I could in one pass to make your job easier.

Regarding me helping with writing patches, I'll do it if I need to but it is
enough work just to inspect all this output to find the bugs in the first
place.  I'd be afraid of making a mistake.  Is there a specific file you could
point me to where all this parsing takes place?  I'll have a look.

I assume have unit tests you run your patches through so we know we aren't 
adding
new bugs as we fix existing ones?  And, I assume you are testing what I say
against the ARM manual so that *I* don't introduce a bug?

...

Here is what I found recently.  BTW, when I give you an example of a bug, it is 
most
likely found in other instructions.  I'm hoping that your fix ends up
eliminating the whole *class* of bugs.  For example, that last undefined bug
regarding P=0 and W=1 was reported for a store.  It also shows up in ldrsb and 
ldrh.
I hope you patch nailed those too?

Without further ado....

0x004000b0 strheq r0, [r0], #-0  <--- objdump is missing the "#-0" (see ARM-ARM 
top of A5-45)

0x004f00b1 strheq r0, [pc], #-1  <--- objdump has r0, [pc, #-1]

0x005fffff ldrsheq pc, [pc], #-255 <--- objdump has pc, [pc, #-255]

0x00500090 <-- should be undefined not ldrbeq

0x006fffbf <-- P=0 so can't be right

0x00700090 bit 26 is zero so can't be ldrbeq...I think it is undefined

0x007fffff ldrsheq pc, [pc, #-255]! <-- objdump is missing the "!" since bit 
21=1

0x00cf00b0 strheq r0, [pc], #0 <--- objdump has r0, [pc, #0]  (bit24=0)
  (likewise for 0x00df00b0 and 0x00dfffff)

0x00ffffff ldrsheq pc, [pc, #255] <-- can't be right since P=0

0x0100f000 <-- obdjump say this is a tstpeq....What is tstp? No such thing!

0x01100090 <-- Can't be ldrbeq since bit26 is zero.  I think is undefined

0x0120f096 <-- objdump has "<illegal shifter operand>".  That should be fixed.

0x01300090 <--Can't be ldrbeq since bit26 =0.  I think is undefined.

0x01400000 <-- Should be mrseq not cmpeq since bit 20=0

0x016000b0 strheq r0, [r0, #-0]! <-- objdump has r0, [r0]! which is wrong

cs


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=10924

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