ubuntu_ftrace_smoke_test failed on T-4.4 ARM64

[Po-Hsu Lin]

This test has failed on T-4.4 ARM64 (moonshot).

 Running '/home/ubuntu/autotest/client/tests/ubuntu_ftrace_smoke_test/ubuntu_ftrace_smoke_test.sh'
 PASSED (CONFIG_FUNCTION_TRACER=y in /boot/config-4.4.0-144-generic)
 PASSED (CONFIG_FUNCTION_GRAPH_TRACER=y in /boot/config-4.4.0-144-generic)
 PASSED (CONFIG_STACK_TRACER=y in /boot/config-4.4.0-144-generic)
 PASSED (CONFIG_DYNAMIC_FTRACE=y in /boot/config-4.4.0-144-generic)
 FAILED /sys/kernel/debug/tracing/kprobe_events does not exist
 FAILED /sys/kernel/debug/tracing/kprobe_profile does not exist
 FAILED /sys/kernel/debug/tracing/uprobe_events does not exist
 FAILED /sys/kernel/debug/tracing/uprobe_profile does not exist
 PASSED (function_graph in /sys/kernel/debug/tracing/available_tracers)
 PASSED (function in /sys/kernel/debug/tracing/available_tracers)
 PASSED (nop in /sys/kernel/debug/tracing/available_tracers)
 PASSED (function can be enabled)
 PASSED (SyS_write or ksys_write traces found must be > 32, got 4341)
 PASSED (function_graph can be enabled)
 PASSED (vfs_write traces found must be > 32, got 1830545)
 PASSED (tracer blk can be enabled (got 2 lines of tracing output))
 PASSED (tracer function_graph can be enabled (got 112212 lines of tracing output))
 PASSED (tracer wakeup_dl can be enabled (got 2 lines of tracing output))
 PASSED (tracer wakeup_rt can be enabled (got 47 lines of tracing output))
 PASSED (tracer wakeup can be enabled (got 47 lines of tracing output))
 PASSED (tracer function can be enabled (got 102306 lines of tracing output))
 Summary: 17 passed, 4 failed

[Po-Hsu Lin (cypressyew)]

Tested with the kernel in -updates (4.4.0-143-generic #169~14.04.2-Ubuntu), this issue still exist

[Colin Ian King (colin-king)]

CONFIG_KPROBE_EVENTS is required for this to work. I'll sort this out.

[Colin Ian King (colin-king)]

So in fact CONFIG_KPROBES and CONFIG_KPROBES_ON_FTRACE are required, however thet are not defined in the /boot/config-4.4.0-143-generic. Strange, since the common ubuntu config has it defined:

debian.master/config/config.common.ubuntu:CONFIG_KPROBES=y
debian.master/config/config.common.ubuntu:CONFIG_KPROBES_ON_FTRACE=y

[Colin Ian King (colin-king)]

Turns out that KPROBES was not added to arm64 until Jul 2016 so it's not supported in Xenial ARM64

commit 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Author: Sandeepa Prabhu <email address hidden>
Date: Fri Jul 8 12:35:48 2016 -0400

    arm64: Kprobes with single stepping support

[Colin Ian King (colin-king)]

@Sam, do you mind re-testing this; I've pushed the fix to the autotest repo

[Po-Hsu Lin (cypressyew)]

This issue will be gone with the fix.
Thank you!