[x64] inject into different-architecture child: x64 to WOW64, WOW64 to x64

From bruen...@google.com on June 12, 2012 09:52:13

this was PR 254193

xref issue #20 (closed) : handle execve of different-architecture child: 32 to 64, 64 to 32 xref issue #147 (closed) /PR 408318: client interactions with cross-arch execve

xref PR 240257: support 32-bit clients on WOW64? how mix 32 and 64 bit code? xref issue #49 /PR 253431 xref issue #381 /PR 215423 (xref PR 249112: [x64] inject into child process) (xref issue #142 (closed) /PR 251677: [x64] early inject into child process)

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old notes which may not all apply:

For deciding which DR to inject, probably should just have 64-bit config take precedence: if 32-bit config is also present, too bad, it gets ignored.

For the child-doesn't-equal parent cases we'll have to have the other architecture's bootstrap code to inject into the child (or for 64-to-32 fool the loader into loading the 32-bit lib if go early and run 64-bit bootstrap code): will require a cross-compiled asm routine, or gencode, for inject-into-thread.

Perhaps worth reconsidering what we really want to bother to support here (PR 240257).

One plan is to never support 32-bit DR following into 64-bit child. Long-term we'll only support 64-bit-DR in WOW64 following children (PR 253431). Only when a client hasn't been ported will we support 32-bit DR in a WOW64 process, So if dr64 is in a process that launches a wow64 child foo.exe where foo.exe has only a wow64 config, our stance is that we won't inject into the child (since we don't bother to support cross-arch child injection) and you'll have to rely on AppInit.

Original issue: http://code.google.com/p/dynamorio/issues/detail?id=803