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authorCong Wang <xiyou.wangcong@gmail.com>2019-11-29 20:52:18 -0800
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-12-02 11:07:00 -0500
commit6c3edaf9fd6a3be7fb5bc6931897c24cd3848f84 (patch)
treef450c75fabff3fe5bc612e15bcd97c4fbaec00c1 /kernel/trace/Kconfig
parent02a65a0bfbef5c644f520885a0a85b45b9703cf3 (diff)
downloadlwn-6c3edaf9fd6a3be7fb5bc6931897c24cd3848f84.tar.gz
lwn-6c3edaf9fd6a3be7fb5bc6931897c24cd3848f84.zip
tracing: Introduce trace event injection
We have been trying to use rasdaemon to monitor hardware errors like correctable memory errors. rasdaemon uses trace events to monitor various hardware errors. In order to test it, we have to inject some hardware errors, unfortunately not all of them provide error injections. MCE does provide a way to inject MCE errors, but errors like PCI error and devlink error don't, it is not easy to add error injection to each of them. Instead, it is relatively easier to just allow users to inject trace events in a generic way so that all trace events can be injected. This patch introduces trace event injection, where a new 'inject' is added to each tracepoint directory. Users could write into this file with key=value pairs to specify the value of each fields of the trace event, all unspecified fields are set to zero values by default. For example, for the net/net_dev_queue tracepoint, we can inject: INJECT=/sys/kernel/debug/tracing/events/net/net_dev_queue/inject echo "" > $INJECT echo "name='test'" > $INJECT echo "name='test' len=1024" > $INJECT cat /sys/kernel/debug/tracing/trace ... <...>-614 [000] .... 36.571483: net_dev_queue: dev= skbaddr=00000000fbf338c2 len=0 <...>-614 [001] .... 136.588252: net_dev_queue: dev=test skbaddr=00000000fbf338c2 len=0 <...>-614 [001] .N.. 208.431878: net_dev_queue: dev=test skbaddr=00000000fbf338c2 len=1024 Triggers could be triggered as usual too: echo "stacktrace if len == 1025" > /sys/kernel/debug/tracing/events/net/net_dev_queue/trigger echo "len=1025" > $INJECT cat /sys/kernel/debug/tracing/trace ... bash-614 [000] .... 36.571483: net_dev_queue: dev= skbaddr=00000000fbf338c2 len=0 bash-614 [001] .... 136.588252: net_dev_queue: dev=test skbaddr=00000000fbf338c2 len=0 bash-614 [001] .N.. 208.431878: net_dev_queue: dev=test skbaddr=00000000fbf338c2 len=1024 bash-614 [001] .N.1 284.236349: <stack trace> => event_inject_write => vfs_write => ksys_write => do_syscall_64 => entry_SYSCALL_64_after_hwframe The only thing that can't be injected is string pointers as they require constant string pointers, this can't be done at run time. Link: http://lkml.kernel.org/r/20191130045218.18979-1-xiyou.wangcong@gmail.com Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/Kconfig')
-rw-r--r--kernel/trace/Kconfig9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index f67620499faa..29a9c5058b62 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -672,6 +672,15 @@ config HIST_TRIGGERS
See Documentation/trace/histogram.rst.
If in doubt, say N.
+config TRACE_EVENT_INJECT
+ bool "Trace event injection"
+ depends on TRACING
+ help
+ Allow user-space to inject a specific trace event into the ring
+ buffer. This is mainly used for testing purpose.
+
+ If unsure, say N.
+
config MMIOTRACE_TEST
tristate "Test module for mmiotrace"
depends on MMIOTRACE && m