Re: [PATCH] [2/31] CPA: Do a simple self test at boot

Harvey Harrison
2008-01-15T08:47:48Z

On Mon, 2008-01-14 at 23:16 +0100, Andi Kleen wrote:
> When CONFIG_DEBUG_RODATA is enabled undo the ro mapping and redo it again.
> This gives some simple testing for change_page_attr()
>
> Optional patch, but I find it useful.
>
> Signed-off-by: Andi Kleen <ak@suse.de>
>
> ---
> arch/x86/Kconfig.debug | 5 +++++
> arch/x86/mm/init_32.c | 26 ++++++++++++++++++++++++++
> arch/x86/mm/init_64.c | 10 ++++++++++
> 3 files changed, 41 insertions(+)
>
> Index: linux/arch/x86/mm/init_64.c
> ===================================================================
> --- linux.orig/arch/x86/mm/init_64.c
> +++ linux/arch/x86/mm/init_64.c
> @@ -603,6 +603,16 @@ void mark_rodata_ro(void)
> * of who is the culprit.
> */
> global_flush_tlb();

global_flush_tlb outside CONFIG_CPA_DEBUG here.

> +
> +#ifdef CONFIG_CPA_DEBUG
> + printk("Testing CPA: undo %lx-%lx\n", start, end);
> + change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, PAGE_KERNEL);
> + global_flush_tlb();
> +
> + printk("Testing CPA: again\n");
> + change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, PAGE_KERNEL_RO);
> + global_flush_tlb();
> +#endif
> }
> #endif
>
> Index: linux/arch/x86/mm/init_32.c
> ===================================================================
> --- linux.orig/arch/x86/mm/init_32.c
> +++ linux/arch/x86/mm/init_32.c
> @@ -793,6 +793,20 @@ void mark_rodata_ro(void)
> change_page_attr(virt_to_page(start),
> size >> PAGE_SHIFT, PAGE_KERNEL_RX);
> printk("Write protecting the kernel text: %luk\n", size >> 10);
> +
> +#ifdef CONFIG_CPA_DEBUG
> + global_flush_tlb();
> +

global_flush_tlb inside CONFIG_CPA_DEBUG here.

> + printk("Testing CPA: Reverting %lx-%lx\n", start, start+size);
> + change_page_attr(virt_to_page(start), size>>PAGE_SHIFT,
> + PAGE_KERNEL_EXEC);
> + global_flush_tlb();
> +
> + printk("Testing CPA: write protecting again\n");
> + change_page_attr(virt_to_page(start), size>>PAGE_SHIFT,
> + PAGE_KERNEL_RX);
> + global_flush_tlb();
> +#endif
> }
> #endif
> start += size;
> @@ -809,6 +823,18 @@ void mark_rodata_ro(void)
> * of who is the culprit.
> */
> global_flush_tlb();

global_flush_tlb outside CONFIG_CPA_DEBUG here. Intentional?

> +
> +#ifdef CONFIG_CPA_DEBUG
> + printk("Testing CPA: undo %lx-%lx\n", start, start + size);
> + change_page_attr(virt_to_page(start), size >> PAGE_SHIFT,
> + PAGE_KERNEL);
> + global_flush_tlb();
> +
> + printk("Testing CPA: write protecting again\n");
> + change_page_attr(virt_to_page(start), size >> PAGE_SHIFT,
> + PAGE_KERNEL_RO);
> + global_flush_tlb();
> +#endif

Cheers,

Harvey