Adushistova at 09:57, 27 October 2011

2011-10-27T09:57:44Z

RBot: Bot (Edward's framework)

2007-03-06T03:34:03Z

Bot (Edward's framework)

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This is documentation for using KFI.

See <code>README.kfi</code> inside the kfi user-space tarfile for a quick overview.

Rough outline:
== Introduction ==
- Description
- Theory of operation
- callout instrumentation
- gcc option
- -finstrument_functions
- static run vs. dynamic run
- initiating and terminating a trace run
- reading the data from the trace buffer
- trace buffer size issues
- tracing overhead issues

== Using KFI ==
- Apply patch found at [[Kernel Function Instrumentation]]
- configure kernel
- decide whether to do a static or dynamic run
- edit kfistatic.conf
- compile kfi for target
- Makefile uses $CROSS_COMPILE to indicate toolchain prefix (same as Linux kernel)
- set this in environment variable, and run make
- make device node on target
- execute the command <code>mknod /dev/kfi c 10 51</code> on the target
static run:
- run kernel
- run <code>kfi</code> to collect trace buffer
- run post-trace tools to examine data
dynamic run:
- run kernel
- run <code>kfi</code> to set up a trace
- run <code>kfi</code> to read a trace
- run post-trace tools to examine data

== Using the post-trace analysis tools ==
- kfiresolve.py
- resolves numeric addresses to function names, in a kfiboot log
- requires System.map for kernel from which dump was made
- kd - kfiboot dump
- filters and formats a kfiboot log
- finds time spent locally and in sub-functions, to isolate where time is being spent
- kt - kfi tree (not finished yet)
- generates call tree from kfiboot log, and reports time spent in branches

== Configuring a kfi trace ==
- kfistatic.conf
- filters:
- start
- stop
- time threshold (duration)
- interrupt
- user id (not implemented yet)

Filter types:
- DEV/NONE - system call???
- TIME - time since boot or start of trace
- FUNC_ENTRY - function entry
- FUNC_EXIT - function exit
- LOG_FULL - trace buffer full
- multiple trace buffers??

== Tasks: ==
- creating a static run
- creating a dynamic run

== Miscelaneous Info ==
- trace structures:
- trigger structure:
- type (one of: DEV, NONE, TIME, ENTRY, EXIT, FULL)
- time or func_addr
- mark - time at which this trigger occurred
- filter structure
- min_delta
- max_delta
- no_ints
- only_ints
- func_list - list of functions
- trace entry structure
- va - VA of instrumented function
- call_site - where this func was called from
- time - function entry time since trigger start time, in usec
- delta - delta time from entry to exit, in usec
- pid - process ID at time of call
- run structure
- int triggered;
- int complete;
- struct kfi_trigger start_trigger;
- struct kfi_trigger stop_trigger;
- struct kfi_filters filters;
- struct kfi_entry* log;
- int num_entries;
- int next_entry;
- int id;
- struct kfi_run * next;

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KFI Docs - Revision history

Adushistova at 09:57, 27 October 2011

RBot: Bot (Edward's framework)