As you probably know, when using ftrace, Linux kernel tracing can be performed by the function name. However, we still need to know the address of the original function in order to call it.You can use kallsyms— a list of all kernel symbols — to get the address of the needed function...
The rest of the ftrace tool framework is much more involved. There are ways to trace latency. The ftrace infrastructure created the static trace events which even perf utilizes, in which there are over a 1,000 in the current Linux kernel and more being added every day. The static trace ev...
Is it possible to display or retrieve ftrace data from the kernel crash dump? What is the use of the crash extensiontrace? Resolution Ifftracefunctionality was enabled on the system while collecting the kernel crash dump then thecrashextensiontracecan be used to display or retrieve ftrace data f...
In order to understand what happens internally in the kernel when ssh is being frozen, we can use ftrace and trigger freezing of processes using a power management debug feature.(Note that we could also have used the Freezer cgroup to freeze only one process here) We first configure the powe...
tasks(E) memory-full-oom-kill(F) kill-all-tasks(I) thaw-filesystems(J) saK show-backtrace-all-active-cpus(L) show-memory-usage(M) nice-all-RT-tasks(N) powerOff show-registers(P) show-all-timers(Q) unRaw Sync show-task-states(T) Unmount show-blocked-tasks(W) dump-ftrace-buffer(...
For more information in general on stap, please refer to the knowledge-base article What is SystemTap and how to use it? Stap is available for Red Hat Enterprise Linux 5 and above. Perf Perf is a userspace tool which interacts with the ftrace subsystem of the kernel to perform tracing wi...
This new method allows for a function to be immediately redirected through aftracehandler, so instead of calling an older, vulnerable function, it is redirected to a patched version of the function. Your patching cadence might involve running something like an Ansible playbook or manually patching ...
During guest launch, we can use theftrace utilityto display the inhibit reasons using thekvm_apicv_inhibit_changedtracepoint: Copy code snippet Copied to Clipboard Error: Could not Copy Copied to Clipboard Error: Could not Copy qemu-kvm-1661305 [141] ... 429704.679440: kvm_apicv_inhibit_chang...
开启需要我们写一个内核model,call register_wide_hw_breakpoint API,当然,Linux的sample中也有例子是可以直接用的。 地址如下:https://code.woboq.org/linux/linux/samples/hw_breakpoint/data_breakpoint.c.html code如下: /** data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address ...
As an extreme example, I wrote cachestat(8) while on vacation in 2014 for use on the Netflix cloud, which was a mix of Linux 3.2 and 3.13 at the time. BPF didn't exist on those versions, so I used basic Ftrace capabilities that were available on Linux 3.2. I described this approac...