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    Subject[PATCH] Text Edit Lock - x86_64 Use kernel_tex_is_ro
    Text Edit Lock - x86_64 Use kernel_tex_is_ro

    It makes more sense to use the kernel_text_is_ro variable instead of
    duplicating it.

    And since we do not plan to call kernel_text_mark_rw()/kernel_text_unmark()
    in the middle of mark_rodata_ro (we are still at boot time), there is no
    need to wait until after global_flush_tlb() mark the rodata.

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    CC: Andi Kleen <andi@firstfloor.org>
    CC: Christoph Hellwig <hch@infradead.org>
    ---
    arch/x86_64/mm/init.c | 12 +++---------
    1 file changed, 3 insertions(+), 9 deletions(-)

    Index: linux-2.6-lttng/arch/x86_64/mm/init.c
    ===================================================================
    --- linux-2.6-lttng.orig/arch/x86_64/mm/init.c 2007-07-14 16:10:21.000000000 -0400
    +++ linux-2.6-lttng/arch/x86_64/mm/init.c 2007-07-14 16:11:47.000000000 -0400
    @@ -56,10 +56,6 @@ static unsigned long dma_reserve __initd

    DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

    -#ifdef CONFIG_DEBUG_RODATA
    -static int rodata_marked;
    -#endif
    -
    /*
    * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
    * physical space so we can cache the place of the first one and move
    @@ -605,13 +601,12 @@ void mark_rodata_ro(void)
    unsigned long start = PFN_ALIGN(_stext);
    unsigned long end = PFN_ALIGN(__end_rodata);

    - kernel_text_is_ro = 1;
    -
    change_page_attr_addr(start, (end - start) >> PAGE_SHIFT,
    PAGE_KERNEL_RO);

    printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
    (end - start) >> 10);
    + kernel_text_is_ro = 1;

    /*
    * change_page_attr_addr() requires a global_flush_tlb() call after it.
    @@ -620,7 +615,6 @@ void mark_rodata_ro(void)
    * of who is the culprit.
    */
    global_flush_tlb();
    - rodata_marked = 1;
    }

    /*
    @@ -628,7 +622,7 @@ void mark_rodata_ro(void)
    */
    void kernel_text_mark_rw(unsigned long address, size_t len)
    {
    - if (rodata_marked && address >= PFN_ALIGN(_text)
    + if (kernel_text_is_ro && address >= PFN_ALIGN(_text)
    && (address + len) <= PFN_ALIGN(_etext)) {
    unsigned long nr_pages;
    nr_pages = ((address + len) >> PAGE_SHIFT)
    @@ -644,7 +638,7 @@ EXPORT_SYMBOL_GPL(kernel_text_mark_rw);

    void kernel_text_unmark(unsigned long address, size_t len)
    {
    - if (rodata_marked && address >= PFN_ALIGN(_text)
    + if (kernel_text_is_ro && address >= PFN_ALIGN(_text)
    && (address + len) <= PFN_ALIGN(_etext)) {
    unsigned long nr_pages;
    nr_pages = ((address + len) >> PAGE_SHIFT)
    --
    Mathieu Desnoyers
    Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
    -
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