** Changed in: linux (Ubuntu Jammy)
Status: In Progress => Fix Committed
** Changed in: ubuntu-z-systems
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1977962
Title:
[UBUNTU 21.10] s390/perf: obtain sie_block from the right address
Status in Ubuntu on IBM z Systems:
Fix Committed
Status in linux package in Ubuntu:
Invalid
Status in linux source package in Jammy:
Fix Committed
Bug description:
Description: s390/perf: obtain sie_block from the right address
Symptom: Read from unitialized stack memory, incorrect guest
perf data reported, possibly system crash.
Problem: When perf is instructed to record a software-based event and
to trace the guest, i.e. using the following command:
perf kvm --guest --guestvmlinux=endless.elf top -e cpu-clock
The reported guest instruction pointer is inaccurate or
the system may crash.
This is caused by the sie_block being taken from empty1[0]
in sie_block() in arch/s390/kernel/perf_event.c, but since
1179f170b6f0 ("s390: fix fpu restore in entry.S")
it resides at empty1[1].
Solution: Obtain sie_block from the right address in sie_block().
Reproduction: 1. Start a KVM guest executing an endless loop.
2. Determine the instruction address of the loop.
3. Start perf recording for any software event and trace
the guest, for example using this command:
perf kvm --guest --guestvmlinux=endless.elf top -e
cpu-clock
4. The reported guest instruction addresses don't match
the loop's instruction address or the system crashes.
Upstream-ID: c9bfb460c3e4da2462e16b0f0b200990b36b1dd2
BBPF Probl.ID: 198450
Preventive: yes
Reported: -
SupportTicket: -
Reference: -
Date: 2022-06-02
Author: n...@linux.ibm.com
Component: kernel
Link:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c9bfb460c3e4da2462e16b0f0b200990b36b1dd2
Problem occurs / affects impish and jammy
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