[Valgrind-developers] preliminary PPC patch against CVS valgrind

[Paul M. <pa...@sa...>]

I have recently found some time to work on getting my PPC port of
Valgrind adapted to the current CVS version.  I have put my current
patch at:

http://ozlabs.org/~paulus/valgrind-cvs-040423.patch.gz

for people to look at if they are interested to see what I have
changed.

It is basically functioning but there are still some bugs left to be
found, and there are parts of the code that are just a quick hack to
get it working rather than the way I would like to see things done in
the long run.  Also, I haven't implemented core dumps for PPC, and
vg_libpthread.c is going to need a lot more work.

Areas where I have needed to modify things (apart from things I
modified in the older patch against 2.1.0) include:

* Stack management in the UME stuff.  In particular the code relating
  to finding and modifying the aux vector needed some changes.

* Code that deals with memory ranges.  I have changed this to cope
  with ranges that end at 0xffffffff, since I have been working on
  this under a ppc64 kernel.

* I had to change VG_(map_file_segment) so that it doesn't try to read
  symbols twice if it finds two mappings of a library which both have
  offset 0.  Because vg_inject.so is relatively small, and ELF
  mappings on PPC use a 64kB alignment, both the text and the data
  mapping end up having offset 0.

* Similarly I had to change the code which clears the BSS so that it
  clears the correct amount when the alignment specified in the ELF
  file (64kB on PPC) is different from the kernel page size.

I'd like to continue the discussion about how Valgrind should be
structured so as to support multiple architectures cleanly.  I could
make up some patches that would abstract a few things that are
different between architectures - things like defining FIRST_ARCH_REG,
LAST_ARCH_REG, etc. and using them instead of R_EAX, R_EDI, etc.

Paul.