linux-kernel - [PATCH 0/3] ftrace: Introduce PERMANENT ftrace

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Message-Id: <20191007081714.20259-1-mbenes@suse.cz>
Date:   Mon,  7 Oct 2019 10:17:11 +0200
From:   Miroslav Benes <mbenes@...e.cz>
To:     rostedt@...dmis.org, mingo@...hat.com, jpoimboe@...hat.com,
        jikos@...nel.org, pmladek@...e.com, joe.lawrence@...hat.com
Cc:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
        Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH 0/3] ftrace: Introduce PERMANENT ftrace_ops flag

Livepatch uses ftrace for redirection to new patched functions. It is
thus directly affected by ftrace sysctl knobs such as ftrace_enabled.
Setting ftrace_enabled to 0 also disables all live patched functions. It
is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.

Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set, the tracing of the function is not
disabled. Such ftrace_ops can still be unregistered in a standard way.

The patch set passes ftrace and livepatch kselftests.

Miroslav Benes (3):
  ftrace: Make test_rec_ops_needs_regs() generic
  ftrace: Introduce PERMANENT ftrace_ops flag
  livepatch: Use FTRACE_OPS_FL_PERMANENT

 Documentation/trace/ftrace-uses.rst |  6 ++++
 Documentation/trace/ftrace.rst      |  2 ++
 include/linux/ftrace.h              |  8 +++--
 kernel/livepatch/patch.c            |  3 +-
 kernel/trace/ftrace.c               | 47 ++++++++++++++++++++++++-----
 5 files changed, 55 insertions(+), 11 deletions(-)

-- 
2.23.0