tree 58002261f3b7335b9dc9f17bdf095997c91da10e
parent 4868402d9582bfb00a5f0157ae5d7ffd2d539fb0
author Steven Rostedt <srostedt@redhat.com> 1256663711 -0400
committer Steven Rostedt <rostedt@goodmis.org> 1256663711 -0400

tracing: allow to change permissions for text with dynamic ftrace enabled

The commit 74e081797bd9d2a7d8005fe519e719df343a2ba8
x86-64: align RODATA kernel section to 2MB with CONFIG_DEBUG_RODATA
prevents text sections from becoming read/write using set_memory_rw.

The dynamic ftrace changes all text pages to read/write just before
converting the calls to tracing to nops, and vice versa.

I orginally just added a flag to allow this transaction when ftrace
did the change, but I also found that when the CPA testing was running
it would remove the read/write as well, and ftrace does not do the text
conversion on boot up, and the CPA changes caused the dynamic tracer
to fail on self tests.

The current solution I have is to simply not to prevent
change_page_attr from setting the RW bit for kernel text pages.

Reported-by: Ingo Molnar <mingo@elte.hu>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>