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Re: gdb won't single-step over ARM integer divide opcode


On 05/08/15 19:02, John Breitenbach wrote:
I did some debugging and have found that the function,
arm_get_next_pc_raw, inappropriately decodes this opcode as a load into
the PC register.  (bits 24..27 are 7, bit 20 is set, and the dest
register appears to be the PC.

Binutils's logic to disassemble the sdiv/udiv opcodes has opcode &
0x0ff0f0f0 = 0x0710f010 (with bit 21 distinguishing between udiv and sdiv)

I've come up with the following patch which makes my situation work. But
I don't know how complete it is, as there may be other newer opcodes
which fall into the formerly undefined instruction space.

Hi John,
Thanks for your patch, however, I think I've fixed this problem in
patch https://sourceware.org/ml/gdb-patches/2015-06/msg00610.html
Does it work for you?  This commit will be in 7.10 release.


Also, the comment "byte write to PC" around line 4930 seems wrong, as
the check for bit 22 a few lines earlier catches that situation, and
what's left is word writes to the PC."


Yeah, it is possible.  Patch is welcome :)

--
Yao (éå)


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