Comments (18)
namhyung
commented on August 29, 2024
1
Forgot to fix the warnings, pushed review/xray-support-v3 again. Thanks!
from uftrace.
Taeung
commented on August 29, 2024
Hi @namhyung 😄
I tested this new feature with uftrace built by gcc-5.4.0.
This feature works fine when testing Clang X-ray dynamic tracing as you tested.
(excluding the warning messages "warning: ignoring return value .." I told you on recent code review)
However,
I found segmentation fault with uftrace built by gcc-7.0.1.
Isn't it needed to care gcc-7.0.1 just yet ?
I tested on the below environment.
$ cd git/uftrace
$ git status | head -1
On branch review/xray-support-v1
$ gcc -dumpversion
7.0.1
$ sudo make clean && sudo make install
$ clang --version
clang version 4.0.0-svn297204-1~exp1 (branches/release_40)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
And I tested Clang X-ray dynamic tracing like below.
$ clang -fxray-instrument -fxray-instruction-threshold=1 -o abc-xray tests/s-abc.c
$ objdump -d abc-xray
...
0000000000423100 <main>:
423100: eb 09 jmp 42310b <main+0xb>
423102: 66 0f 1f 84 00 00 02 nopw 0x200(%rax,%rax,1)
423109: 00 00
42310b: 55 push %rbp
42310c: 48 89 e5 mov %rsp,%rbp
42310f: 48 83 ec 20 sub $0x20,%rsp
423113: c7 45 fc 00 00 00 00 movl $0x0,-0x4(%rbp)
42311a: 89 7d f8 mov %edi,-0x8(%rbp)
42311d: 48 89 75 f0 mov %rsi,-0x10(%rbp)
423121: c7 45 ec 00 00 00 00 movl $0x0,-0x14(%rbp)
423128: 83 7d f8 01 cmpl $0x1,-0x8(%rbp)
42312c: 0f 8e 10 00 00 00 jle 423142 <main+0x42>
423132: 48 8b 45 f0 mov -0x10(%rbp),%rax
423136: 48 8b 78 08 mov 0x8(%rax),%rdi
42313a: e8 71 e9 fd ff callq 401ab0 <atoi@plt>
42313f: 89 45 ec mov %eax,-0x14(%rbp)
423142: e8 39 00 00 00 callq 423180 <a>
423147: b9 01 00 00 00 mov $0x1,%ecx
42314c: 31 d2 xor %edx,%edx
42314e: 03 45 ec add -0x14(%rbp),%eax
423151: 89 45 ec mov %eax,-0x14(%rbp)
423154: 83 7d ec 00 cmpl $0x0,-0x14(%rbp)
423158: 0f 45 ca cmovne %edx,%ecx
42315b: 89 c8 mov %ecx,%eax
42315d: 48 83 c4 20 add $0x20,%rsp
423161: 5d pop %rbp
423162: c3 retq
423163: 2e 66 0f 1f 84 00 00 nopw %cs:0x200(%rax,%rax,1)
42316a: 02 00 00
42316d: 0f 1f 00 nopl (%rax)
423170: df a0 42 00 00 00 fbld 0x42(%rax)
423176: 00 00 add %al,(%rax)
423178: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
42317f: 00
...
$ uftrace -P main abc-xray
WARN: invalid task file
child terminated by signal: 11: Segmentation fault
# DURATION TID FUNCTION
So I checked it by gdb with core file like below.
gdb tell me that seg fault occurs at libmcount/plthook.c:429
$ gdb abc-xray core
...
Reading symbols from abc-xray...(no debugging symbols found)...done.
[New LWP 14972]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `abc-xray'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007f8b01a57022 in plthook_entry (ret_addr=0x7ffc712b17f8, child_idx=53,
module_id=140235009253736, regs=0x7ffc712b17b8)
at /home/taeung/git/uftrace/libmcount/plthook.c:429
429 struct ftrace_trigger tr = {
(gdb) bt
#0 0x00007f8b01a57022 in plthook_entry (ret_addr=0x7ffc712b17f8, child_idx=53,
module_id=140235009253736, regs=0x7ffc712b17b8)
at /home/taeung/git/uftrace/libmcount/plthook.c:429
#1 0x00007f8b01a61cfa in plt_hooker () from /usr/local/lib/libmcount.so
#2 0x0000000000401e89 in _start ()
The same problem occurs when testing just dynamic tracing with uftrace built by gcc-7.0.1.
The result from core file is same.
$ gcc -o t-abc -pg -mfentry -mnop-mcount tests/s-abc.c
$ uftrace -P main t-abc
WARN: invalid task file
child terminated by signal: 11: Segmentation fault
# DURATION TID FUNCTION
from uftrace.
namhyung
commented on August 29, 2024
Thank you very much for testing this. I have two questions:
- Does it crash dynamic tracing only? Or normal tracing is also broken?
- Is it a problem of PLT hook code? IOW,
--no-libcallis ok?
from uftrace.
Taeung
commented on August 29, 2024
It seems about just gcc 7..
I tested with uftrace built by gcc 7 like below.
- Yes, normal tracing is also broken.
$ uftrace abc
WARN: invalid task file
child terminated by signal: 11: Segmentation fault
# DURATION TID FUNCTION
- Okey but dynamic tracing is not ok.
case A) normal tracing [OK]
uftrace --no-libcall abc
# DURATION TID FUNCTION
[ 4037] | main() {
[ 4037] | a() {
[ 4037] | b() {
0.633 us [ 4037] | c();
1.960 us [ 4037] | } /* b */
2.197 us [ 4037] | } /* a */
2.582 us [ 4037] | } /* main */
case B) dynamic tracing [NG]
$ uftrace --no-libcall -P main abc.dyn
WARN: invalid task file
child terminated by signal: 11: Segmentation fault
# DURATION TID FUNCTION
Sorry, it seems better to make this problem new issue about gcc 7.
Because this problem is about not only xray / dynamic tracing but also normal tracing..
from uftrace.
Taeung
commented on August 29, 2024
And @namhyung I found the warning message about warning: ignoring return value
, when building uftrace by gcc 5.4.1.
So I commented here 😄
from uftrace.
namhyung
commented on August 29, 2024
Pushed review/xray-support-v2.
from uftrace.
Taeung
commented on August 29, 2024
Hi @namhyung ,
uftrace built by gcc 5 or gcc 6 work fine on xray-test you mentioned.
However, I found the similar segfault (at libmcount/mcount.c:714) on xray-test, again.
(The code is contained in e87574b)
gcc : 7.0.1
clang : 4.2.1
git-branch : review/xray-support-v3
xray-testenvironment
$ git pull upstream review/xray-support-v3
From https://github.com/namhyung/uftrace
* branch review/xray-support-v3 -> FETCH_HEAD
Already up-to-date.
$ git status | head -1
On branch review/xray-support-v3
$ gcc -dumpversion
7.0.1
$ sudo make clean && sudo make install
$ date && ll uftrace /usr/local/lib/libmcount*
Wed Apr 26 13:54:54 KST 2017
-rwxr-xr-x 1 root root 489048 2017-04-26 13:55:41 /usr/local/lib/libmcount-fast-single.so*
-rwxr-xr-x 1 root root 490424 2017-04-26 13:55:41 /usr/local/lib/libmcount-fast.so*
-rwxr-xr-x 1 root root 8192 2017-04-26 13:55:41 /usr/local/lib/libmcount-nop.so*
-rwxr-xr-x 1 root root 500416 2017-04-26 13:55:41 /usr/local/lib/libmcount-single.so*
-rwxr-xr-x 1 root root 501448 2017-04-26 13:55:41 /usr/local/lib/libmcount.so*
-rwxr-xr-x 1 root root 1314744 2017-04-26 13:55:33 uftrace*
- Build target program
abc-xraybuilt byclang 4
$ clang -dumpversion
4.2.1
$ clang -fxray-instrument -fxray-instruction-threshold=1 -o abc-xray tests/s-abc.c
- Segmentation fault on
xray-test
$ uftrace -P main abc-xray
child terminated by signal: 11: Segmentation fault
# DURATION TID FUNCTION
- If checking it with
gdband core file, you can see the segfault at libmcount/mcount.c:714
$ gdb abc-xray core
...
Reading symbols from abc-xray...(no debugging symbols found)...done.
[New LWP 4986]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `abc-xray'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007fdf15b48802 in xray_entry (parent=140721932945512, child=4337925,
regs=0x7ffc60d34830) at /home/taeung/git/uftrace/libmcount/mcount.c:714
714 struct ftrace_trigger tr = {
from uftrace.
namhyung
commented on August 29, 2024
Thanks a lot for testing! Could you please test below again?
diff --git a/arch/x86_64/xray.S b/arch/x86_64/xray.S
index de58da3..261e54b 100644
--- a/arch/x86_64/xray.S
+++ b/arch/x86_64/xray.S
@@ -7,44 +7,41 @@
.type __xray_entry, @function
__xray_entry:
.cfi_startproc
- sub $56, %rsp
- .cfi_adjust_cfa_offset 56
+ sub $48, %rsp
+ .cfi_adjust_cfa_offset 48
- movq %rdi, 48(%rsp)
+ movq %rdi, 40(%rsp)
.cfi_offset rdi, -24
- movq %rsi, 40(%rsp)
+ movq %rsi, 32(%rsp)
.cfi_offset rsi, -32
- movq %rdx, 32(%rsp)
+ movq %rdx, 24(%rsp)
.cfi_offset rdx, -40
- movq %rcx, 24(%rsp)
+ movq %rcx, 16(%rsp)
.cfi_offset rcx, -48
- movq %r8, 16(%rsp)
+ movq %r8, 8(%rsp)
.cfi_offset r8, -56
- movq %r9, 8(%rsp)
+ movq %r9, 0(%rsp)
.cfi_offset r9, -64
- movq %rax, 0(%rsp)
- .cfi_offset rax, -72
/* child ip */
- movq 56(%rsp), %rsi
+ movq 48(%rsp), %rsi
/* parent ip */
- lea 64(%rsp), %rdi
+ lea 56(%rsp), %rdi
/* mcount_args */
- lea 8(%rsp), %rdx
+ movq %rsp, %rdx
call xray_entry
- movq 0(%rsp), %rax
- movq 8(%rsp), %r9
- movq 16(%rsp), %r8
- movq 24(%rsp), %rcx
- movq 32(%rsp), %rdx
- movq 40(%rsp), %rsi
- movq 48(%rsp), %rdi
-
- add $56, %rsp
- .cfi_adjust_cfa_offset -56
+ movq 0(%rsp), %r9
+ movq 8(%rsp), %r8
+ movq 16(%rsp), %rcx
+ movq 24(%rsp), %rdx
+ movq 32(%rsp), %rsi
+ movq 40(%rsp), %rdi
+
+ add $48, %rsp
+ .cfi_adjust_cfa_offset -48
retq
.cfi_endproc
from uftrace.
Taeung
commented on August 29, 2024
Okey, I'll tell you the result of your patch ! 😄
from uftrace.
Taeung
commented on August 29, 2024
Fine ! the segfault is gone, @namhyung
from uftrace.
Taeung
commented on August 29, 2024
But I found the similar segfault on original dynamic tracing.
So I added new issue !
from uftrace.
namhyung
commented on August 29, 2024
Yep, I think there's a problem too. Even -mfentry (not dynamic) option will crash due to the same problem IMHO.
from uftrace.
namhyung
commented on August 29, 2024
Pushed review/xray-support-v4 with the fix and a testcase.
from uftrace.
Taeung
commented on August 29, 2024
@namhyung I checked new test case of 90f95a16
I thought the case that testers use old clang (e.g. clang 3.8 that can't support xray).
Sure, this test script can show BI (Build failed).
But how about using sys.stderr or Popen() to tell tester correct build error messages such as:
Case 1) Using sys.stderr when building test cases:
diff --git a/tests/runtest.py b/tests/runtest.py
index f8e0522..13a3d85 100755
--- a/tests/runtest.py
+++ b/tests/runtest.py
@@ -59,7 +59,7 @@ class TestBase:
self.pr_debug("build command: %s" % build_cmd)
try:
- if sp.call(build_cmd.split(), stdout=sp.PIPE, stderr=sp.PIPE) != 0:
+ if sp.call(build_cmd.split(), stdout=sp.PIPE, stderr=sys.stderr) != 0:
return TestBase.TEST_BUILD_FAIL
return TestBase.TEST_SUCCESS
except:
Then, we can see build error like below without -v option:
$ ./runtest.py xray
Test case pg finstrument-fu
------------------------: O0 O1 O2 O3 Os O0 O1 O2 O3 Os
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
140 dynamic_xray : BI BI BI BI BI BI BI BI BI BI
Or,
Case 2) Using Popen() instead of subprocess.call() to show build error message:
diff --git a/tests/runtest.py b/tests/runtest.py
index f8e0522..e1645ac 100755
--- a/tests/runtest.py
+++ b/tests/runtest.py
@@ -59,7 +59,10 @@ class TestBase:
self.pr_debug("build command: %s" % build_cmd)
try:
- if sp.call(build_cmd.split(), stdout=sp.PIPE, stderr=sp.PIPE) != 0:
+ p = sp.Popen(build_cmd.split(), stdout=sp.PIPE, stderr=sp.PIPE)
+ sp.stdout, sp.stderr = p.communicate()
+ if p.returncode != 0:
+ self.pr_debug(sp.stderr)
return TestBase.TEST_BUILD_FAIL
return TestBase.TEST_SUCCESS
except:
Then, we can see the error message only with -v option
./runtest.py -v xray
Test case pg finstrument-fu
------------------------: O0 O1 O2 O3 Os O0 O1 O2 O3 Os
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
build command: clang -o t-abc -fno-inline -fno-builtin -fno-omit-frame-pointer -fxray-instrument -fxray-instruction-threshold=1 s-abc.c
clang: error: unknown argument: '-fxray-instrument'
clang: error: unknown argument: '-fxray-instruction-threshold=1'
140 dynamic_xray : BI BI BI BI BI BI BI BI BI BI
What do you think about this change ?
from uftrace.
namhyung
commented on August 29, 2024
I like the option 2. Can I add it as a separate commit with your sign-off?
from uftrace.
Taeung
commented on August 29, 2024
Sure, you can do that 😄
from uftrace.
namhyung
commented on August 29, 2024
Merged: 04991ed
from uftrace.
honggyukim
commented on August 29, 2024
I didn't catch up x-ray support for a while but thanks very much for this work!
from uftrace.
Related Issues (20)
- test: Run test suite on multiple environments HOT 1
- kernel tests failures HOT 1
- cmds: static `tmp_dirname` used stack after return HOT 1
- Give monotonic time offset from real time. HOT 4
- Various runtime issues running numerical simulation HOT 26
- Fix close file descriptor in setup_dwarf_info function to release acquired resource
- Generate uftrace.data in rotation HOT 1
- Add new `hist` command HOT 2
- how to trace a dynamic lib HOT 7
- Build failures with LTO HOT 2
- Segmentation fault with uftrace dump --flame-graph HOT 8
- Typo in README: Redundant 'the' in documentation
- Improve Documentation about Flame Graph (with --sample-time examples) HOT 1
- Compile warning on `‘sizeof’ in the earlier argument and not in the later argument` HOT 2
- Compile warning caused by Python3.12 header from `-Wdeclaration-after-statement` HOT 2
- what should i do when i want to trace a member function? HOT 1
- demangling failure with __device_stub_ prefix HOT 5
- "./misc/demangler --unknown" triggers segfault
- How to get uftrace data before the process terminates? HOT 3
- Segmentation fault HOT 8
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from uftrace.