lkml.org 
[lkml]   [2009]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] [GIT PULL] tracing: allow to change permissions for text with dynamic ftrace enabled

    * Steven Rostedt <rostedt@goodmis.org> wrote:

    >
    > 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

    Pulled, thanks Steve!

    Ingo


    \
     
     \ /
      Last update: 2009-10-27 19:15    [W:0.025 / U:30.152 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site