[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [RFC 0/2] Fix Coverity and other errors in ppc440_uc DMA

From: Cédric Le Goater
Subject: Re: [RFC 0/2] Fix Coverity and other errors in ppc440_uc DMA
Date: Wed, 27 Jul 2022 10:28:38 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0

On 7/26/22 20:23, Peter Maydell wrote:
This patchset is mainly trying to fix a problem that Coverity spotted
in the dcr_write_dma() function in hw/ppc/ppc440_uc.c, where the code
is not correctly using the cpu_physical_memory_map() function.
While I was fixing that I noticed a second problem in this code,
where it doesn't have a fallback for when cpu_physical_memory_map()
says "I couldn't map that for you".

I've marked these patches as RFC, partly because I don't have any
guest that would exercise the code changes[*],

I build these :


but none of the DCR DMA registers are used.

There are images for the sam460ex images here :


But AFAICT, it does not go beyond the bootloader.

and partly because
I don't have any documentation of the hardware to tell me how it
should behave, so patch 2 in particular has some FIXMEs. I also
notice that the code doesn't update any of the registers like the
count or source/base addresses when the DMA transfer happens, which
seems odd, but perhaps the real hardware does work like that.

I think we should probably take patch 1 (which is a fairly minimal
fix of the use-of-uninitialized-data problem),




but patch 2 is a bit more unfinished.

[*] The commit 3c409c1927efde2fc that added this code says it's used
by AmigaOS.)

-- PMM

Peter Maydell (2):
   hw/ppc/ppc440_uc: Initialize length passed to
   hw/ppc/ppc440_uc: Handle mapping failure in DMA engine

  hw/ppc/ppc440_uc.c | 34 +++++++++++++++++++++++++++++++++-
  1 file changed, 33 insertions(+), 1 deletion(-)

reply via email to

[Prev in Thread] Current Thread [Next in Thread]