Add experimental helpers for calling kernel functions and writing to memory #430
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In all of our current code, we want to document a class separately from its "constructor"; see commit c801e5e ("drgndoc: format __init__() signature separately from class"). But for some trivial classes, like one that will be added in an upcoming change, it makes sense to collapse them. So, for classes with no docstring and one __init__() signature with a docstring, document the class with the __init__() signature and docstring. Signed-off-by: Omar Sandoval <osandov@osandov.com>
An upcoming helper will need these. We also need them from vmtest when _drgn may not be built yet, though, so they can't go in drgn.internal. Create a new package, _drgn_util, and move them there. Signed-off-by: Omar Sandoval <osandov@osandov.com>
An upcoming helper will need some ELF constant definitions. Signed-off-by: Omar Sandoval <osandov@osandov.com>
This will be used by an upcoming helper. Signed-off-by: Omar Sandoval <osandov@osandov.com>
…memory These are highly-requested features that I didn't implement for awhile because I thought they would be too difficult or hacky. The approach that I finally came up with is slightly deranged but solid: we manually generate a kernel module ELF file and machine code to do a function call. An alternative approach that I tried was generating C source code for a kernel module and building it, but that relies on having kernel-devel and a compatible toolchain installed, and it's slow. (Kudos to Matthew Wilcox for suggesting the kernel module approach last year: https://lwn.net/Articles/953256/.) For now, this is under a new drgn.helpers.experimental package, in the drgn.helpers.experimental.kmodify module, with no stability guarantees, but we still have tests for it. Signed-off-by: Omar Sandoval <osandov@osandov.com>
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There are a few preparatory commits moving code around. The top commit has the details.