On Fri, Sep 10, 2021 at 11:19:00AM +0200, Daniel Borkmann wrote: > The tailcall_3 test program uses bpf_tail_call_static() where the JIT > would patch a direct jump. Add a new tailcall_6 test program replicating > exactly the same test just ensuring that bpf_tail_call() uses a map > index where the verifier cannot make assumptions this time. > > In other words, this will now cover both on x86-64 JIT, meaning, JIT > images with emit_bpf_tail_call_direct() emission as well as JIT images > with emit_bpf_tail_call_indirect() emission. > > # echo 1 > /proc/sys/net/core/bpf_jit_enable > # ./test_progs -t tailcalls > #136/1 tailcalls/tailcall_1:OK > #136/2 tailcalls/tailcall_2:OK > #136/3 tailcalls/tailcall_3:OK > #136/4 tailcalls/tailcall_4:OK > #136/5 tailcalls/tailcall_5:OK > #136/6 tailcalls/tailcall_6:OK > #136/7 tailcalls/tailcall_bpf2bpf_1:OK > #136/8 tailcalls/tailcall_bpf2bpf_2:OK > #136/9 tailcalls/tailcall_bpf2bpf_3:OK > #136/10 tailcalls/tailcall_bpf2bpf_4:OK > #136/11 tailcalls/tailcall_bpf2bpf_5:OK > #136 tailcalls:OK > Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED > > # echo 0 > /proc/sys/net/core/bpf_jit_enable > # ./test_progs -t tailcalls > #136/1 tailcalls/tailcall_1:OK > #136/2 tailcalls/tailcall_2:OK > #136/3 tailcalls/tailcall_3:OK > #136/4 tailcalls/tailcall_4:OK > #136/5 tailcalls/tailcall_5:OK > #136/6 tailcalls/tailcall_6:OK > [...] > > For interpreter, the tailcall_1-6 tests are passing as well. The later > tailcall_bpf2bpf_* are failing due lack of bpf2bpf + tailcall support > in interpreter, so this is expected. > > Also, manual inspection shows that both loaded programs from tailcall_3 > and tailcall_6 test case emit the expected opcodes: > > * tailcall_3 disasm, emit_bpf_tail_call_direct(): > > [...] > b: push %rax > c: push %rbx > d: push %r13 > f: mov %rdi,%rbx > 12: movabs $0xffff8d3f5afb0200,%r13 > 1c: mov %rbx,%rdi > 1f: mov %r13,%rsi > 22: xor %edx,%edx _ > 24: mov -0x4(%rbp),%eax | limit check > 2a: cmp $0x20,%eax | > 2d: ja 0x0000000000000046 | > 2f: add $0x1,%eax | > 32: mov %eax,-0x4(%rbp) |_ > 38: nopl 0x0(%rax,%rax,1) > 3d: pop %r13 > 3f: pop %rbx > 40: pop %rax > 41: jmpq 0xffffffffffffe377 > [...] > > * tailcall_6 disasm, emit_bpf_tail_call_indirect(): > > [...] > 47: movabs $0xffff8d3f59143a00,%rsi > 51: mov %edx,%edx > 53: cmp %edx,0x24(%rsi) > 56: jbe 0x0000000000000093 _ > 58: mov -0x4(%rbp),%eax | limit check > 5e: cmp $0x20,%eax | > 61: ja 0x0000000000000093 | > 63: add $0x1,%eax | > 66: mov %eax,-0x4(%rbp) |_ > 6c: mov 0x110(%rsi,%rdx,8),%rcx > 74: test %rcx,%rcx > 77: je 0x0000000000000093 > 79: pop %rax > 7a: mov 0x30(%rcx),%rcx > 7e: add $0xb,%rcx > 82: callq 0x000000000000008e > 87: pause > 89: lfence > 8c: jmp 0x0000000000000087 > 8e: mov %rcx,(%rsp) > 92: retq > [...] > > Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> > Cc: Johan Almbladh <johan.almbladh@xxxxxxxxxxxxxxxxx> > Cc: Paul Chaignon <paul@xxxxxxxxx> > Cc: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> > Link: https://lore.kernel.org/bpf/CAM1=_QRyRVCODcXo_Y6qOm1iT163HoiSj8U2pZ8Rj3hzMTT=HQ@xxxxxxxxxxxxxx Acked-by: Paul Chaignon <paul@xxxxxxxxx>
