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Date:   Mon, 6 May 2019 13:06:43 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
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Subject: Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call
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On Mon, 6 May 2019 09:17:19 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> So what is it that doesn't actually work? I've looked at the patch
> even more, and I can't for the life of me see how it wouldn't work.
> 
> Of course, I didn't test any of the actual ftrace parts, since I
> short-circuited them intentionally with the above test function hack.
> I have no idea what the semantics for those
> ftrace_location(ip)/is_ftrace_caller(ip) cases are supposed to be, I
> only tested that yes, the infrastructure clearly emulates a call
> instruction.

Can you try booting with:

CONFIG_KPROBE_EVENTS=y
CONFIG_UPROBE_EVENTS=y
CONFIG_DYNAMIC_EVENTS=y
CONFIG_PROBE_EVENTS=y
CONFIG_DYNAMIC_FTRACE=y
CONFIG_DYNAMIC_FTRACE_WITH_REGS=y
CONFIG_FUNCTION_PROFILER=y
CONFIG_FTRACE_MCOUNT_RECORD=y
CONFIG_FTRACE_SELFTEST=y
CONFIG_FTRACE_STARTUP_TEST=y
CONFIG_TRACEPOINT_BENCHMARK=y
CONFIG_RING_BUFFER_BENCHMARK=y
CONFIG_RING_BUFFER_STARTUP_TEST=y


And see if it boots?

-- Steve