From: 赵佳炜 <phoenix500526@163.com>
To: "Yonghong Song" <yonghong.song@linux.dev>
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re:Re: [PATCH v7 2/2] selftests/bpf: Force -O2 for USDT selftests to cover SIB handling logic
Date: Tue, 12 Aug 2025 15:02:12 +0800 (CST) [thread overview]
Message-ID: <65e51538.57aa.1989d162bb8.Coremail.phoenix500526@163.com> (raw)
In-Reply-To: <0f6d16c1-0e85-4709-9846-3a993a9f041b@linux.dev>
Yes, I've tried that but it didn't help. FYI:
$ readelf -nsr usdt_rip
Relocation section '.rela.dyn' at offset 0x530 contains 9 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000003df0 000000000008 R_X86_64_RELATIVE 1150
000000003df8 000000000008 R_X86_64_RELATIVE 1110
000000004008 000000000008 R_X86_64_RELATIVE 4008
000000004018 000000000008 R_X86_64_RELATIVE 1160
000000003fd8 000100000006 R_X86_64_GLOB_DAT 0000000000000000 __libc_start_main@GLIBC_2.34 + 0
000000003fe0 000200000006 R_X86_64_GLOB_DAT 0000000000000000 _ITM_deregisterTM[...] + 0
000000003fe8 000300000006 R_X86_64_GLOB_DAT 0000000000000000 __gmon_start__ + 0
000000003ff0 000400000006 R_X86_64_GLOB_DAT 0000000000000000 _ITM_registerTMCl[...] + 0
000000003ff8 000500000006 R_X86_64_GLOB_DAT 0000000000000000 __cxa_finalize@GLIBC_2.2.5 + 0
Symbol table '.dynsym' contains 6 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 FUNC GLOBAL DEFAULT UND _[...]@GLIBC_2.34 (2)
2: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterT[...]
3: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
4: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMC[...]
5: 0000000000000000 0 FUNC WEAK DEFAULT UND [...]@GLIBC_2.2.5 (3)
Symbol table '.symtab' contains 42 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 FILE LOCAL DEFAULT ABS Scrt1.o
2: 000000000000038c 32 OBJECT LOCAL DEFAULT 4 __abi_tag
3: 0000000000000000 0 FILE LOCAL DEFAULT ABS usdt_rip.c
4: 0000000000004021 1 OBJECT LOCAL DEFAULT 25 ti
5: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
6: 00000000000010a0 0 FUNC LOCAL DEFAULT 14 deregister_tm_clones
7: 00000000000010d0 0 FUNC LOCAL DEFAULT 14 register_tm_clones
8: 0000000000001110 0 FUNC LOCAL DEFAULT 14 __do_global_dtors_aux
9: 0000000000004020 1 OBJECT LOCAL DEFAULT 25 completed.0
10: 0000000000003df8 0 OBJECT LOCAL DEFAULT 21 __do_global_dtor[...]
11: 0000000000001150 0 FUNC LOCAL DEFAULT 14 frame_dummy
12: 0000000000003df0 0 OBJECT LOCAL DEFAULT 20 __frame_dummy_in[...]
13: 0000000000000000 0 FILE LOCAL DEFAULT ABS damo.c
14: 0000000000004022 1 OBJECT LOCAL DEFAULT 25 ti
15: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
16: 00000000000020d8 0 OBJECT LOCAL DEFAULT 19 __FRAME_END__
17: 0000000000000000 0 FILE LOCAL DEFAULT ABS
18: 0000000000003e00 0 OBJECT LOCAL DEFAULT 22 _DYNAMIC
19: 0000000000002008 0 NOTYPE LOCAL DEFAULT 18 __GNU_EH_FRAME_HDR
20: 0000000000003fc0 0 OBJECT LOCAL DEFAULT 23 _GLOBAL_OFFSET_TABLE_
21: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __libc_start_mai[...]
22: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterT[...]
23: 0000000000004000 0 NOTYPE WEAK DEFAULT 24 data_start
24: 0000000000001160 8 FUNC GLOBAL DEFAULT 14 add
25: 0000000000004020 0 NOTYPE GLOBAL DEFAULT 24 _edata
26: 0000000000002004 1 NOTYPE WEAK HIDDEN 17 _.stapsdt.base
27: 0000000000004010 8 OBJECT GLOBAL DEFAULT 24 t1
28: 0000000000001168 0 FUNC GLOBAL HIDDEN 15 _fini
29: 0000000000004000 0 NOTYPE GLOBAL DEFAULT 24 __data_start
30: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
31: 0000000000004008 0 OBJECT GLOBAL HIDDEN 24 __dso_handle
32: 0000000000002000 4 OBJECT GLOBAL DEFAULT 16 _IO_stdin_used
33: 0000000000004028 0 NOTYPE GLOBAL DEFAULT 25 _end
34: 0000000000001070 38 FUNC GLOBAL DEFAULT 14 _start
35: 0000000000004020 0 NOTYPE GLOBAL DEFAULT 25 __bss_start
36: 0000000000001040 48 FUNC GLOBAL DEFAULT 14 main
37: 0000000000004018 8 OBJECT GLOBAL DEFAULT 24 add_ptr
38: 0000000000004020 0 OBJECT GLOBAL HIDDEN 24 __TMC_END__
39: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMC[...]
40: 0000000000000000 0 FUNC WEAK DEFAULT UND __cxa_finalize@G[...]
41: 0000000000001000 0 FUNC GLOBAL HIDDEN 11 _init
Displaying notes found in: .note.gnu.property
Owner Data size Description
GNU 0x00000020 NT_GNU_PROPERTY_TYPE_0
Properties: x86 feature: IBT, SHSTK
x86 ISA needed: x86-64-baseline
Displaying notes found in: .note.gnu.build-id
Owner Data size Description
GNU 0x00000014 NT_GNU_BUILD_ID (unique build ID bitstring)
Build ID: eb615daa575687cc44edc1d339b27890c12c27f1
Displaying notes found in: .note.ABI-tag
Owner Data size Description
GNU 0x00000010 NT_GNU_ABI_TAG (ABI version tag)
OS: Linux, ABI: 3.2.0
Displaying notes found in: .note.stapsdt
Owner Data size Description
stapsdt 0x00000066 NT_STAPSDT (SystemTap probe descriptors)
Provider: usdt_rip
Name: rip_global_var
Location: 0x0000000000001058, Base: 0x0000000000002004, Semaphore: 0x0000000000000000
Arguments: -1@ti(%rip) 8@add_ptr(%rip) -1@4+t1(%rip) -1@ti(%rip)
At 2025-08-12 13:06:40, "Yonghong Song" <yonghong.song@linux.dev> wrote:
>
>
>On 8/10/25 1:55 AM, 赵佳炜 wrote:
>>
>>
>> Hi Yonghong,
>>
>> I found another issue where symbols can be duplicated, and I’m not sure how to tell them apart.
>>
>> For example, I created two C files named usdt_rip.c and hello.c. Both define their own static ti variables, like:`static volatile char ti = 0;`.
>>
>> After compiling, I obtained an ELF file usdt_rip whose .symtab contains the following entries:
>>
>> $ readelf -s usdt_rip
>>
>> Symbol table '.symtab' contains 42 entries:
>> Num: Value Size Type Bind Vis Ndx Name
>> 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
>> 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS Scrt1.o
>> 2: 000000000000038c 32 OBJECT LOCAL DEFAULT 4 __abi_tag
>> 3: 0000000000000000 0 FILE LOCAL DEFAULT ABS usdt_rip.c
>> 4: 0000000000004021 1 OBJECT LOCAL DEFAULT 25 ti
>> 5: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
>> 6: 00000000000010a0 0 FUNC LOCAL DEFAULT 14 deregister_tm_clones
>> 7: 00000000000010d0 0 FUNC LOCAL DEFAULT 14 register_tm_clones
>> 8: 0000000000001110 0 FUNC LOCAL DEFAULT 14 __do_global_dtors_aux
>> 9: 0000000000004020 1 OBJECT LOCAL DEFAULT 25 completed.0
>> 10: 0000000000003df8 0 OBJECT LOCAL DEFAULT 21 __do_global_dtor[...]
>> 11: 0000000000001150 0 FUNC LOCAL DEFAULT 14 frame_dummy
>> 12: 0000000000003df0 0 OBJECT LOCAL DEFAULT 20 __frame_dummy_in[...]
>> 13: 0000000000000000 0 FILE LOCAL DEFAULT ABS damo.c
>> 14: 0000000000004022 1 OBJECT LOCAL DEFAULT 25 ti
>> 15: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
>> 16: 00000000000020d8 0 OBJECT LOCAL DEFAULT 19 __FRAME_END__
>>
>>
>> As you can see, there are two ti variables in the .symtab section. Their values are very close, making them hard to distinguish.
>>
>> I’m unsure how to handle this situation. Do you have any suggestions?
>
>Did you check relocations? Relocaitons should be able to point exact which symbol.
>
>>
>> Thanks,
>> Jiawei Zhao
>[...]
next prev parent reply other threads:[~2025-08-12 7:02 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-06 9:24 [PATCH v7 0/2] libbpf: fix USDT SIB argument handling causing unrecognized register error Jiawei Zhao
2025-08-06 9:24 ` [PATCH v7 1/2] " Jiawei Zhao
2025-08-06 9:24 ` [PATCH v7 2/2] selftests/bpf: Force -O2 for USDT selftests to cover SIB handling logic Jiawei Zhao
2025-08-06 18:17 ` Yonghong Song
2025-08-07 2:57 ` 赵佳炜
2025-08-07 18:01 ` Yonghong Song
2025-08-10 8:55 ` 赵佳炜
2025-08-10 9:39 ` 赵佳炜
2025-08-12 5:06 ` Yonghong Song
2025-08-12 7:02 ` 赵佳炜 [this message]
2025-08-12 16:11 ` Yonghong Song
2025-08-13 2:27 ` 赵佳炜
2025-08-13 5:24 ` Yonghong Song
2025-08-13 6:23 ` 赵佳炜
2025-08-17 13:43 ` 赵佳炜
2025-08-18 17:35 ` Yonghong Song
2025-08-19 9:50 ` 赵佳炜
2025-08-20 20:57 ` Yonghong Song
2025-08-20 23:00 ` Andrii Nakryiko
2025-08-21 15:38 ` 赵佳炜
2025-08-21 18:28 ` Andrii Nakryiko
2025-08-22 15:39 ` 赵佳炜
2025-08-07 9:28 ` Jiri Olsa
2025-08-06 18:07 ` [PATCH v7 0/2] libbpf: fix USDT SIB argument handling causing unrecognized register error Yonghong Song
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