From: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
With bpf_jit_binary_pack_finalize invoked, we copy
rw_header to header and then image/insn is valid.
Write a test BPF prog which include subprog:
$ llvm-objdump -d subprog.o
Disassembly of section .text:
0000000000000000 <subprog>:
0: 18 01 00 00 73 75 62 70 00 00 00 00 72 6f 67 00 r1 = 29114459903653235 ll
2: 7b 1a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r1
3: bf a1 00 00 00 00 00 00 r1 = r10
4: 07 01 00 00 f8 ff ff ff r1 += -8
5: b7 02 00 00 08 00 00 00 r2 = 8
6: 85 00 00 00 06 00 00 00 call 6
7: 95 00 00 00 00 00 00 00 exit
Disassembly of section raw_tp/sys_enter:
0000000000000000 <entry>:
0: 85 10 00 00 ff ff ff ff call -1
1: b7 00 00 00 00 00 00 00 r0 = 0
2: 95 00 00 00 00 00 00 00 exit
Without this patch, kernel print message:
[ 580.775387] flen=8 proglen=51 pass=3 image=ffffffffa000c20c from=kprobe-load pid=1643
[ 580.777236] JIT code: 00000000: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
[ 580.779037] JIT code: 00000010: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
[ 580.780767] JIT code: 00000020: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
[ 580.782568] JIT code: 00000030: cc cc cc
$ bpf_jit_disasm
51 bytes emitted from JIT compiler (pass:3, flen:8)
ffffffffa000c20c + <x>:
0: int3
1: int3
2: int3
3: int3
4: int3
5: int3
...
To fix this issue:
[ 260.016071] flen=3 proglen=20 pass=1 image=ffffffffa000c11c from=kprobe-load pid=1568
[ 260.018094] JIT code: 00000000: 0f 1f 44 00 00 66 90 55 48 89 e5 e8 38 00 00 00
[ 260.020124] JIT code: 00000010: 31 c0 c9 c3
[ 260.021229] flen=8 proglen=51 pass=1 image=ffffffffa000c164 from=kprobe-load pid=1568
[ 260.023132] JIT code: 00000000: 0f 1f 44 00 00 66 90 55 48 89 e5 48 81 ec 08 00
[ 260.025129] JIT code: 00000010: 00 00 48 bf 73 75 62 70 72 6f 67 00 48 89 7d f8
[ 260.027199] JIT code: 00000020: 48 89 ef 48 83 c7 f8 be 08 00 00 00 e8 9e 19 1d
[ 260.029226] JIT code: 00000030: e1 c9 c3
$ bpf_jit_disasm
51 bytes emitted from JIT compiler (pass:1, flen:8)
ffffffffa000c164 + <x>:
0: nopl 0x0(%rax,%rax,1)
5: xchg %ax,%ax
7: push %rbp
8: mov %rsp,%rbp
b: sub $0x8,%rsp
12: movabs $0x676f7270627573,%rdi
1c: mov %rdi,-0x8(%rbp)
20: mov %rbp,%rdi
23: add $0xfffffffffffffff8,%rdi
27: mov $0x8,%esi
2c: callq 0xffffffffe11d19cf
31: leaveq
32: retq
$ bpf_jit_disasm
20 bytes emitted from JIT compiler (pass:1, flen:3)
ffffffffa000c11c + <x>:
0: nopl 0x0(%rax,%rax,1)
5: xchg %ax,%ax
7: push %rbp
8: mov %rsp,%rbp
b: callq 0x0000000000000048
10: xor %eax,%eax
12: leaveq
13: retq
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Yonghong Song <yhs@xxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxx>
Cc: Stanislav Fomichev <sdf@xxxxxxxxxx>
Cc: Hao Luo <haoluo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Hou Tao <houtao1@xxxxxxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 36ffe67ad6e5..4e017102cc16 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2543,9 +2543,6 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
cond_resched();
}
- if (bpf_jit_enable > 1)
- bpf_jit_dump(prog->len, proglen, pass + 1, image);
-
if (image) {
if (!prog->is_func || extra_pass) {
/*
@@ -2561,6 +2558,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
goto out_image;
}
+ if (bpf_jit_enable > 1)
+ bpf_jit_dump(prog->len, proglen, pass + 1, image);
+
bpf_tail_call_direct_fixup(prog);
} else {
jit_data->addrs = addrs;
--
2.27.0
