Merge branch 'Add skb + xdp dynptrs'

Joanne Koong says:

====================

This patchset is the 2nd in the dynptr series. The 1st can be found here [0].

This patchset adds skb and xdp type dynptrs, which have two main benefits for
packet parsing:
    * allowing operations on sizes that are not statically known at
      compile-time (eg variable-sized accesses).
    * more ergonomic and less brittle iteration through data (eg does not need
      manual if checking for being within bounds of data_end)

When comparing the differences in runtime for packet parsing without dynptrs
vs. with dynptrs, there is no noticeable difference. Patch 9 contains more
details as well as examples of how to use skb and xdp dynptrs.

[0] https://lore.kernel.org/bpf/20220523210712.3641569-1-joannelkoong@gmail.com/
---
Changelog:

v12 = https://lore.kernel.org/bpf/20230226085120.3907863-1-joannelkoong@gmail.com/
v12 -> v13:
    * Fix missing { } for case statement

v11 = https://lore.kernel.org/bpf/20230222060747.2562549-1-joannelkoong@gmail.com/
v11 -> v12:
    * Change constant mem size checking to use "__szk" kfunc annotation
      for slices
    * Use autoloading for success selftests

v10 = https://lore.kernel.org/bpf/20230216225524.1192789-1-joannelkoong@gmail.com/
v10 -> v11:
    * Reject bpf_dynptr_slice_rdwr() for non-writable progs at load time
      instead of runtime
    * Add additional patch (__uninit kfunc annotation)
    * Expand on documentation
    * Add bpf_dynptr_write() calls for persisting writes in tests

v9 = https://lore.kernel.org/bpf/20230127191703.3864860-1-joannelkoong@gmail.com/
v9 -> v10:
    * Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr interface
    * Add some more tests
    * Split up patchset into more parts to make it easier to review

v8 = https://lore.kernel.org/bpf/20230126233439.3739120-1-joannelkoong@gmail.com/
v8 -> v9:
    * Fix dynptr_get_type() to check non-stack dynptrs

v7 = https://lore.kernel.org/bpf/20221021011510.1890852-1-joannelkoong@gmail.com/
v7 -> v8:
    * Change helpers to kfuncs
    * Add 2 new patches (1/5 and 2/5)

v6 = https://lore.kernel.org/bpf/20220907183129.745846-1-joannelkoong@gmail.com/
v6 -> v7
    * Change bpf_dynptr_data() to return read-only data slices if the skb prog
      is read-only (Martin)
    * Add test "skb_invalid_write" to test that writes to rd-only data slices
      are rejected

v5 = https://lore.kernel.org/bpf/20220831183224.3754305-1-joannelkoong@gmail.com/
v5 -> v6
    * Address kernel test robot errors by static inlining

v4 = https://lore.kernel.org/bpf/20220822235649.2218031-1-joannelkoong@gmail.com/
v4 -> v5
    * Address kernel test robot errors for configs w/out CONFIG_NET set
    * For data slices, return PTR_TO_MEM instead of PTR_TO_PACKET (Kumar)
    * Split selftests into subtests (Andrii)
    * Remove insn patching. Use rdonly and rdwr protos for dynptr skb
      construction (Andrii)
    * bpf_dynptr_data() returns NULL for rd-only dynptrs. There will be a
      separate bpf_dynptr_data_rdonly() added later (Andrii and Kumar)

v3 = https://lore.kernel.org/bpf/20220822193442.657638-1-joannelkoong@gmail.com/
v3 -> v4
    * Forgot to commit --amend the kernel test robot error fixups

v2 = https://lore.kernel.org/bpf/20220811230501.2632393-1-joannelkoong@gmail.com/
v2 -> v3
    * Fix kernel test robot build test errors

v1 = https://lore.kernel.org/bpf/20220726184706.954822-1-joannelkoong@gmail.com/
v1 -> v2
  * Return data slices to rd-only skb dynptrs (Martin)
  * bpf_dynptr_write allows writes to frags for skb dynptrs, but always
    invalidates associated data slices (Martin)
  * Use switch casing instead of ifs (Andrii)
  * Use 0xFD for experimental kind number in the selftest (Zvi)
  * Put selftest conversions w/ dynptrs into new files (Alexei)
  * Add new selftest "test_cls_redirect_dynptr.c"
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>