Re: linux-next: Tree for Apr 22 (objtool warnings)

Josh Poimboeuf
2020-04-22T16:44:17Z

On Wed, Apr 22, 2020 at 08:35:29AM -0700, Randy Dunlap wrote:
> On 4/22/20 12:10 AM, Stephen Rothwell wrote:
> > Hi all,
> >
> > Changes since 20200421:
> >
>
> on x86_64:

In both cases the unreachable instruction happens immediately after a
call to a function which is truncated with a UD2 (because of
UBSAN_TRAP).

When I remove UBSAN_TRAP, the UD2s are replaced with calls to
__ubsan_handle_type_mismatch_v1().

Kees, any idea?

> arch/x86/net/bpf_jit_comp.o: warning: objtool: bpf_int_jit_compile()+0x246: unreachable instruction

00000000000010a1 <do_jit>:
10a1: 55 push %rbp
10a2: 53 push %rbx
10a3: 48 81 ec d0 00 00 00 sub $0xd0,%rsp
10aa: 48 89 fb mov %rdi,%rbx
10ad: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax
10b4: 00 00
10b6: 48 89 84 24 c8 00 00 mov %rax,0xc8(%rsp)
10bd: 00
10be: 31 c0 xor %eax,%eax
10c0: 48 8b bc 24 e0 00 00 mov 0xe0(%rsp),%rdi
10c7: 00
10c8: e8 00 00 00 00 callq 10cd <do_jit+0x2c>
10c9: R_X86_64_PLT32 __tsan_func_entry-0x4
10cd: f6 c3 07 test $0x7,%bl
10d0: 75 7f jne 1151 <do_jit+0xb0>
10d2: 48 8d 7b 0c lea 0xc(%rbx),%rdi
10d6: e8 00 00 00 00 callq 10db <do_jit+0x3a>
10d7: R_X86_64_PLT32 __tsan_read4-0x4
10db: 48 89 e7 mov %rsp,%rdi
10de: e8 00 00 00 00 callq 10e3 <do_jit+0x42>
10df: R_X86_64_PLT32 __tsan_write8-0x4
10e3: 48 8d 6c 24 08 lea 0x8(%rsp),%rbp
10e8: 48 89 2c 24 mov %rbp,(%rsp)
10ec: 48 8d 7b 04 lea 0x4(%rbx),%rdi
10f0: e8 00 00 00 00 callq 10f5 <do_jit+0x54>
10f1: R_X86_64_PLT32 __tsan_read4-0x4
10f5: 48 8d 7b 20 lea 0x20(%rbx),%rdi
10f9: e8 00 00 00 00 callq 10fe <do_jit+0x5d>
10fa: R_X86_64_PLT32 __tsan_read8-0x4
10fe: 48 8b 7b 20 mov 0x20(%rbx),%rdi
1102: 40 f6 c7 07 test $0x7,%dil
1106: 75 49 jne 1151 <do_jit+0xb0>
1108: 48 83 c7 18 add $0x18,%rdi
110c: e8 00 00 00 00 callq 1111 <do_jit+0x70>
110d: R_X86_64_PLT32 __tsan_read4-0x4
1111: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
1114: R_X86_64_32S ideal_nops
1118: e8 00 00 00 00 callq 111d <do_jit+0x7c>
1119: R_X86_64_PLT32 __tsan_read8-0x4
111d: 48 8b 1d 00 00 00 00 mov 0x0(%rip),%rbx # 1124 <do_jit+0x83>
1120: R_X86_64_PC32 ideal_nops-0x4
1124: 48 8d 7b 48 lea 0x48(%rbx),%rdi
1128: f6 c3 07 test $0x7,%bl
112b: 75 24 jne 1151 <do_jit+0xb0>
112d: e8 00 00 00 00 callq 1132 <do_jit+0x91>
112e: R_X86_64_PLT32 __tsan_read8-0x4
1132: 48 8b 43 48 mov 0x48(%rbx),%rax
1136: 8b 10 mov (%rax),%edx
1138: 89 55 00 mov %edx,0x0(%rbp)
113b: 0f b6 40 04 movzbl 0x4(%rax),%eax
113f: 88 45 04 mov %al,0x4(%rbp)
1142: 48 8d 7c 24 0d lea 0xd(%rsp),%rdi
1147: e8 00 00 00 00 callq 114c <do_jit+0xab>
1148: R_X86_64_PLT32 __tsan_write1-0x4
114c: c6 44 24 0d 55 movb $0x55,0xd(%rsp)
1151: 0f 0b ud2

> drivers/media/i2c/ir-kbd-i2c.o: warning: objtool: ir_probe()+0x745: unreachable instruction

000000000000091e <zilog_init>:
91e: 55 push %rbp
91f: 48 83 ec 70 sub $0x70,%rsp
923: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax
92a: 00 00
92c: 48 89 44 24 68 mov %rax,0x68(%rsp)
931: 31 c0 xor %eax,%eax
933: 48 8b 7c 24 78 mov 0x78(%rsp),%rdi
938: e8 00 00 00 00 callq 93d <zilog_init+0x1f>
939: R_X86_64_PLT32 __tsan_func_entry-0x4
93d: 48 8d 6c 24 08 lea 0x8(%rsp),%rbp
942: be 60 00 00 00 mov $0x60,%esi
947: 48 89 ef mov %rbp,%rdi
94a: e8 00 00 00 00 callq 94f <zilog_init+0x31>
94b: R_X86_64_PLT32 __tsan_write_range-0x4
94f: b9 0c 00 00 00 mov $0xc,%ecx
954: 31 c0 xor %eax,%eax
956: 48 89 ef mov %rbp,%rdi
959: f3 48 ab rep stos %rax,%es:(%rdi)
95c: 48 89 ef mov %rbp,%rdi
95f: e8 00 00 00 00 callq 964 <zilog_init+0x46>
960: R_X86_64_PLT32 __tsan_write1-0x4
964: c6 44 24 08 60 movb $0x60,0x8(%rsp)
969: 0f 0b ud2

--
Josh