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 @@
__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