libbpf-tools/offcputime, futexctn: Fix incorrect DSO information in s… #4902
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
…tacktrace
offcputime may display inaccurate DSO information in the stacktrace.
Here's an example of the issue:
It shows the same DSO offset for different addresses, which is incorrect.
$ ./offcputime -v
..
iovisor#14 0x00007f8b912a8c (/usr/lib/libcbe.so_0x22afa8c)
iovisor#15 0x000044000a3ee0 (/usr/lib/libcbe.so_0x22afa8c)
iovisor#16 0x000044001fc56c (/usr/lib/libcbe.so_0x22afa8c)
This is why syms__map_addr_dso simply returns NULL when syms__find_dso also
returns NULL. In that case, the values of dso_name and dso_offset are not
changed. If the dso_name and dso_offset variables have a garbage value before
calling syms__map_addr_dso, those garbage values are maintained after calling
syms__map_addr_dso.
This patch fixes the issue by reinitializing dso_name and dso_offset variables
before calling syms__map_addr_dso.
ekyooo
requested review from
drzaeus77,
goldshtn,
yonghong-song,
4ast,
brendangregg and
davemarchevsky
as code owners
dkruces
pushed a commit
to dkruces/bcc
that referenced
this pull request
Nov 28, 2024
…tacktrace (iovisor#4902) offcputime may display inaccurate DSO information in the stacktrace. Here's an example of the issue: It shows the same DSO offset for different addresses, which is incorrect. $ ./offcputime -v .. iovisor#14 0x00007f8b912a8c (/usr/lib/libcbe.so_0x22afa8c) iovisor#15 0x000044000a3ee0 (/usr/lib/libcbe.so_0x22afa8c) iovisor#16 0x000044001fc56c (/usr/lib/libcbe.so_0x22afa8c) This is why syms__map_addr_dso simply returns NULL when syms__find_dso also returns NULL. In that case, the values of dso_name and dso_offset are not changed. If the dso_name and dso_offset variables have a garbage value before calling syms__map_addr_dso, those garbage values are maintained after calling syms__map_addr_dso. This patch fixes the issue by reinitializing dso_name and dso_offset variables before calling syms__map_addr_dso. Co-authored-by: Eunseon Lee <[email protected]>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
…tacktrace
offcputime may display inaccurate DSO information in the stacktrace. Here's an example of the issue:
It shows the same DSO offset for different addresses, which is incorrect.
This is why syms__map_addr_dso simply returns NULL when syms__find_dso also returns NULL. In that case, the values of dso_name and dso_offset are not changed. If the dso_name and dso_offset variables have a garbage value before calling syms__map_addr_dso, those garbage values are maintained after calling syms__map_addr_dso.
This patch fixes the issue by reinitializing dso_name and dso_offset variables before calling syms__map_addr_dso.
FYI, there is another PR(#4862) to fix the issue by changing syms__map_addr_dso API.
This PR is to fix the issue in a simple way as the above PR is pending now.