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Pull ftrace updates from Steven Rostedt: - Restructure the function graph shadow stack to prepare it for use with kretprobes With the goal of merging the shadow stack logic of function graph and kretprobes, some more restructuring of the function shadow stack is required. Move out function graph specific fields from the fgraph infrastructure and store it on the new stack variables that can pass data from the entry callback to the exit callback. Hopefully, with this change, the merge of kretprobes to use fgraph shadow stacks will be ready by the next merge window. - Make shadow stack 4k instead of using PAGE_SIZE. Some architectures have very large PAGE_SIZE values which make its use for shadow stacks waste a lot of memory. - Give shadow stacks its own kmem cache. When function graph is started, every task on the system gets a shadow stack. In the future, shadow stacks may not be 4K in size. Have it have its own kmem cache so that whatever size it becomes will still be efficient in allocations. - Initialize profiler graph ops as it will be needed for new updates to fgraph - Convert to use guard(mutex) for several ftrace and fgraph functions - Add more comments and documentation - Show function return address in function graph tracer Add an option to show the caller of a function at each entry of the function graph tracer, similar to what the function tracer does. - Abstract out ftrace_regs from being used directly like pt_regs ftrace_regs was created to store a partial pt_regs. It holds only the registers and stack information to get to the function arguments and return values. On several archs, it is simply a wrapper around pt_regs. But some users would access ftrace_regs directly to get the pt_regs which will not work on all archs. Make ftrace_regs an abstract structure that requires all access to its fields be through accessor functions. - Show how long it takes to do function code modifications When code modification for function hooks happen, it always had the time recorded in how long it took to do the conversion. But this value was never exported. Recently the code was touched due to new ROX modification handling that caused a large slow down in doing the modifications and had a significant impact on boot times. Expose the timings in the dyn_ftrace_total_info file. This file was created a while ago to show information about memory usage and such to implement dynamic function tracing. It's also an appropriate file to store the timings of this modification as well. This will make it easier to see the impact of changes to code modification on boot up timings. - Other clean ups and small fixes * tag 'ftrace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (22 commits) ftrace: Show timings of how long nop patching took ftrace: Use guard to take ftrace_lock in ftrace_graph_set_hash() ftrace: Use guard to take the ftrace_lock in release_probe() ftrace: Use guard to lock ftrace_lock in cache_mod() ftrace: Use guard for match_records() fgraph: Use guard(mutex)(&ftrace_lock) for unregister_ftrace_graph() fgraph: Give ret_stack its own kmem cache fgraph: Separate size of ret_stack from PAGE_SIZE ftrace: Rename ftrace_regs_return_value to ftrace_regs_get_return_value selftests/ftrace: Fix check of return value in fgraph-retval.tc test ftrace: Use arch_ftrace_regs() for ftrace_regs_*() macros ftrace: Consolidate ftrace_regs accessor functions for archs using pt_regs ftrace: Make ftrace_regs abstract from direct use fgragh: No need to invoke the function call_filter_check_discard() fgraph: Simplify return address printing in function graph tracer function_graph: Remove unnecessary initialization in ftrace_graph_ret_addr() function_graph: Support recording and printing the function return address ftrace: Have calltime be saved in the fgraph storage ftrace: Use a running sleeptime instead of saving on shadow stack fgraph: Use fgraph data to store subtime for profiler ...
Linux Ftrace Testcases
This is a collection of testcases for ftrace tracing feature in the Linux
kernel. Since ftrace exports interfaces via the debugfs, we just need
shell scripts for testing. Feel free to add new test cases.
Running the ftrace testcases
============================
At first, you need to be the root user to run this script.
To run all testcases:
$ sudo ./ftracetest
To run specific testcases:
# ./ftracetest test.d/basic3.tc
Or you can also run testcases under given directory:
# ./ftracetest test.d/kprobe/
Contributing new testcases
==========================
Copy test.d/template to your testcase (whose filename must have *.tc
extension) and rewrite the test description line.
* The working directory of the script is <debugfs>/tracing/.
* Take care with side effects as the tests are run with root privilege.
* The tests should not run for a long period of time (more than 1 min.)
These are to be unit tests.
* You can add a directory for your testcases under test.d/ if needed.
* The test cases should run on dash (busybox shell) for testing on
minimal cross-build environments.
* Note that the tests are run with "set -e" (errexit) option. If any
command fails, the test will be terminated immediately.
* The tests can return some result codes instead of pass or fail by
using exit_unresolved, exit_untested, exit_unsupported and exit_xfail.
Result code
===========
Ftracetest supports following result codes.
* PASS: The test succeeded as expected. The test which exits with 0 is
counted as passed test.
* FAIL: The test failed, but was expected to succeed. The test which exits
with !0 is counted as failed test.
* UNRESOLVED: The test produced unclear or intermidiate results.
for example, the test was interrupted
or the test depends on a previous test, which failed.
or the test was set up incorrectly
The test which is in above situation, must call exit_unresolved.
* UNTESTED: The test was not run, currently just a placeholder.
In this case, the test must call exit_untested.
* UNSUPPORTED: The test failed because of lack of feature.
In this case, the test must call exit_unsupported.
* XFAIL: The test failed, and was expected to fail.
To return XFAIL, call exit_xfail from the test.
There are some sample test scripts for result code under samples/.
You can also run samples as below:
# ./ftracetest samples/
TODO
====
* Fancy colored output :)