tree 2f9dbc73e9f4ed58aa7e1c51334f5680913e62ed
parent f6f2625faebf784b9d335a58a7b71c8f33686d2c
author Luis Hector Chavez <lhchavez@google.com> 1576257153 -0800
committer Luis Hector Chavez <lhchavez@google.com> 1576521755 -0800

Add a way to compile .policy files at build-time

This change adds enough Android.bp rules and tools to make it possible
to compile .policy files at build-time, using the new optimizing
compiler.

This is achieved by compiling the libconstants.gen.c and
libsyscalls.gen.c into LLVM IR files (which are roughly
architecture-neutral for our purposes). These IR files are then parsed
by the `tools/generate_constants_json.py` script and produces an
architecture-specific `constants.json` file, which can be fed into
`tools/compile_seccomp_policy.py` to compile .policy files.

The last piece of the puzzle is to actually invoke the script. This
needs to be done from a cc_genrule due to the way that soong handles
target variations, and will produce artifacts that are
architecture-specific. One example to invoke the script is as follows:

    cc_genrule {
        name: "bpf_compilation",
        host_supported: true,
        vendor_available: true,
        recovery_available: true,
        tools: ["minijail_compile_seccomp_policy"],
        cmd: "$(location minijail_compile_seccomp_policy) --arch-json $(in) $(out)",
        srcs: [":minijail_constants_json", "my_seccomp.policy"],
        out: ["my_seccomp.bpf"],
    }

Bug: None
Test: mmma -j external/minijail
Test: make all
Change-Id: I835ee18c3ff515a6f3203ed86d20ad41d4f5d066