bpf trampoline for arm64

Add bpf trampoline support for arm64. Most of the logic is the same as
x86.

Tested on raspberry pi 4b and qemu with KASLR disabled (avoid long jump),
result:
 #9  /1     bpf_cookie/kprobe:OK
 #9  /2     bpf_cookie/multi_kprobe_link_api:FAIL
 #9  /3     bpf_cookie/multi_kprobe_attach_api:FAIL
 #9  /4     bpf_cookie/uprobe:OK
 #9  /5     bpf_cookie/tracepoint:OK
 #9  /6     bpf_cookie/perf_event:OK
 #9  /7     bpf_cookie/trampoline:OK
 #9  /8     bpf_cookie/lsm:OK
 #9         bpf_cookie:FAIL
 #18 /1     bpf_tcp_ca/dctcp:OK
 #18 /2     bpf_tcp_ca/cubic:OK
 #18 /3     bpf_tcp_ca/invalid_license:OK
 #18 /4     bpf_tcp_ca/dctcp_fallback:OK
 #18 /5     bpf_tcp_ca/rel_setsockopt:OK
 #18        bpf_tcp_ca:OK
 #51 /1     dummy_st_ops/dummy_st_ops_attach:OK
 #51 /2     dummy_st_ops/dummy_init_ret_value:OK
 #51 /3     dummy_st_ops/dummy_init_ptr_arg:OK
 #51 /4     dummy_st_ops/dummy_multiple_args:OK
 #51        dummy_st_ops:OK
 #55        fentry_fexit:OK
 #56        fentry_test:OK
 #57 /1     fexit_bpf2bpf/target_no_callees:OK
 #57 /2     fexit_bpf2bpf/target_yes_callees:OK
 #57 /3     fexit_bpf2bpf/func_replace:OK
 #57 /4     fexit_bpf2bpf/func_replace_verify:OK
 #57 /5     fexit_bpf2bpf/func_sockmap_update:OK
 #57 /6     fexit_bpf2bpf/func_replace_return_code:OK
 #57 /7     fexit_bpf2bpf/func_map_prog_compatibility:OK
 #57 /8     fexit_bpf2bpf/func_replace_multi:OK
 #57 /9     fexit_bpf2bpf/fmod_ret_freplace:OK
 #57        fexit_bpf2bpf:OK
 #58        fexit_sleep:OK
 #59        fexit_stress:OK
 #60        fexit_test:OK
 #67        get_func_args_test:OK
 #68        get_func_ip_test:OK
 #104       modify_return:OK
 #237       xdp_bpf2bpf:OK

bpf_cookie/multi_kprobe_link_api and bpf_cookie/multi_kprobe_attach_api
failed due to lack of multi_kprobe on arm64.

v4:
- Run the test cases on raspberry pi 4b
- Rebase and add cookie to trampoline
- As Steve suggested, move trace_direct_tramp() back to entry-ftrace.S to
  avoid messing up generic code with architecture specific code
- As Jakub suggested, merge patch 4 and patch 5 of v3 to provide full function
  in one patch
- As Mark suggested, add a comment for the use of aarch64_insn_patch_text_nosync()
- Do not generate trampoline for long jump to avoid triggering ftrace_bug
- Round stack size to multiples of 16B to avoid SPAlignmentFault
- Use callee saved register x20 to reduce the use of mov_i64
- Add missing BTI J instructions
- Trivial spelling and code sytle fixes

v3: https://lore.kernel.org/bpf/20220424154028.1698685-1-xuku...
- Append test results for bpf_tcp_ca, dummy_st_ops, fexit_bpf2bpf,
  xdp_bpf2bpf
- Support to poke bpf progs
- Fix return value of arch_prepare_bpf_trampoline() to the total number
  of bytes instead of number of instructions 
- Do not check whether CONFIG_DYNAMIC_FTRACE_WITH_REGS is enabled in
  arch_prepare_bpf_trampoline, since the trampoline may be hooked to a bpf
  prog
- Restrict bpf_arch_text_poke() to poke bpf text only, as kernel functions
  are poked by ftrace
- Rewrite trace_direct_tramp() in inline assembly in trace_selftest.c
  to avoid messing entry-ftrace.S
- isolate arch_ftrace_set_direct_caller() with macro
  CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS to avoid compile error
  when this macro is disabled
- Some trivial code sytle fixes

v2: https://lore.kernel.org/bpf/20220414162220.1985095-1-xuku...
- Add Song's ACK
- Change the multi-line comment in is_valid_bpf_tramp_flags() into net
  style (patch 3)
- Fix a deadloop issue in ftrace selftest (patch 2)
- Replace pt_regs->x0 with pt_regs->orig_x0 in patch 1 commit message 
- Replace "bpf trampoline" with "custom trampoline" in patch 1, as
  ftrace direct call is not only used by bpf trampoline.

v1: https://lore.kernel.org/bpf/20220413054959.1053668-1-xuku...

Xu Kuohai (6):
  arm64: ftrace: Add ftrace direct call support
  ftrace: Fix deadloop caused by direct call in ftrace selftest
  bpf: Move is_valid_bpf_tramp_flags() to the public trampoline code
  bpf, arm64: Impelment bpf_arch_text_poke() for arm64
  bpf, arm64: bpf trampoline for arm64
  selftests/bpf: Fix trivial typo in fentry_fexit.c

 arch/arm64/Kconfig                            |   2 +
 arch/arm64/include/asm/ftrace.h               |  22 +
 arch/arm64/kernel/asm-offsets.c               |   1 +
 arch/arm64/kernel/entry-ftrace.S              |  28 +-
 arch/arm64/net/bpf_jit.h                      |   1 +
 arch/arm64/net/bpf_jit_comp.c                 | 523 +++++++++++++++++-
 arch/x86/net/bpf_jit_comp.c                   |  20 -
 include/linux/bpf.h                           |   6 +
 kernel/bpf/bpf_struct_ops.c                   |   4 +-
 kernel/bpf/trampoline.c                       |  34 +-
 kernel/trace/trace_selftest.c                 |   2 +
 .../selftests/bpf/prog_tests/fentry_fexit.c   |   4 +-
 12 files changed, 603 insertions(+), 44 deletions(-)

-- 
2.30.2