Re: [PATCH v3] ARM: mm: fix reporting of read-only PMD bits

From: Rob Herring
Date: Sat Mar 22 2014 - 12:45:55 EST


On Sat, Mar 22, 2014 at 10:16 AM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> On non-LPAE ARMv6+, read-only PMD bits are defined with the combination
> "PMD_SECT_APX | PMD_SECT_AP_WRITE". Adjusted the bit masks to correctly
> report this.
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> v3:
> - check for pre-v6 CPUs on the page table report.
> v2:
> - reorder bits, suggested by Olof.
> ---
> arch/arm/mm/dump.c | 31 +++++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
> index ef69152f9b52..c1122d266c45 100644
> --- a/arch/arm/mm/dump.c
> +++ b/arch/arm/mm/dump.c
> @@ -121,23 +121,42 @@ static const struct prot_bits pte_bits[] = {
>
> static const struct prot_bits section_bits[] = {
> #ifndef CONFIG_ARM_LPAE
> - /* These are approximate */
> +# if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_V6K) || defined(CONFIG_CPU_V7)

You can simplify the ifdef logic like this:

#ifdef CONFIG_ARM_LPAE /* Implies v7 */

#elif __LINUX_ARM_ARCH__ >= 6

#else
/* v4/v5 */
#endif
--
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