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Subject[PATCH] [GIT PULL] tracing: allow to change permissions for text with dynamic ftrace enabled
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Ingo,

The cause of the ftrace bug you saw in tip/master was caused by a change
in tip's x86/mm branch.

Please pull the latest tip/x86/mm tree, which can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/x86/mm


Steven Rostedt (1):
tracing: allow to change permissions for text with dynamic ftrace enabled

----
arch/x86/mm/pageattr.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
---------------------------
commit 883242dd0e5faaba041528a9a99f483f2a656c83
Author: Steven Rostedt <srostedt@redhat.com>
Date: Tue Oct 27 13:15:11 2009 -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>

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index b494fc4..78d3168 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -279,7 +279,8 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
__pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_RW;

-#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
+#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA) && \
+ !defined(CONFIG_DYNAMIC_FTRACE)
/*
* Kernel text mappings for the large page aligned .rodata section
* will be read-only. For the kernel identity mappings covering



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