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bpf trampoline for arm64 #470

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wants to merge 7 commits into from
Closed

bpf trampoline for arm64 #470

wants to merge 7 commits into from

Commits on May 23, 2022

  1. adding ci files

    Kernel Patches Daemon committed May 23, 2022
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  2. arm64: ftrace: Add ftrace direct call support 

    Add ftrace direct support for arm64.

1. When there is custom trampoline only, replace the fentry nop to a
   jump instruction that jumps directly to the custom trampoline.

2. When ftrace trampoline and custom trampoline coexist, jump from
   fentry to ftrace trampoline first, then jump to custom trampoline
   when ftrace trampoline exits. The current unused register
   pt_regs->orig_x0 is used as an intermediary for jumping from ftrace
   trampoline to custom trampoline.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: KP Singh <kpsingh@kernel.org>
    Xu Kuohai authored and Kernel Patches Daemon committed May 23, 2022
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  3. ftrace: Fix deadloop caused by direct call in ftrace selftest 

    After direct call is enabled for arm64, ftrace selftest enters a
dead loop:

<trace_selftest_dynamic_test_func>:
00  bti     c
01  mov     x9, x30                            <trace_direct_tramp>:
02  bl      <trace_direct_tramp>    ---------->     ret
                                                     |
                                         lr/x30 is 03, return to 03
                                                     |
03  mov     w0, #0x0   <-----------------------------|
     |                                               |
     |                   dead loop!                  |
     |                                               |
04  ret   ---- lr/x30 is still 03, go back to 03 ----|

The reason is that when the direct caller trace_direct_tramp() returns
to the patched function trace_selftest_dynamic_test_func(), lr is still
the address after the instrumented instruction in the patched function,
so when the patched function exits, it returns to itself!

To fix this issue, we need to restore lr before trace_direct_tramp()
exits, so rewrite a dedicated trace_direct_tramp() for arm64.

Reported-by: Li Huafei <lihuafei1@huawei.com>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
    Xu Kuohai authored and Kernel Patches Daemon committed May 23, 2022
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  4. bpf: Remove is_valid_bpf_tramp_flags() 

    BPF_TRAM_F_XXX flags are not used by user code and are almost constant
at compile time, so run time validation is a bit overkill. Remove
is_valid_bpf_tramp_flags() and add some usage comments.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
    Xu Kuohai authored and Kernel Patches Daemon committed May 23, 2022
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  5. bpf, arm64: Impelment bpf_arch_text_poke() for arm64 

    Impelment bpf_arch_text_poke() for arm64, so bpf trampoline code can use
it to replace nop with jump, or replace jump with nop.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
    Xu Kuohai authored and Kernel Patches Daemon committed May 23, 2022
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  6. bpf, arm64: 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.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: KP Singh <kpsingh@kernel.org>
    Xu Kuohai authored and Kernel Patches Daemon committed May 23, 2022
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  7. selftests/bpf: Fix trivial typo in fentry_fexit.c 

    The "ipv6" word in assertion message should be "fentry_fexit".

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
    Xu Kuohai authored and Kernel Patches Daemon committed May 23, 2022
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