Re: [PATCH v11 02/12] scs: add accounting

[Will Deacon]

On Thu, Apr 16, 2020 at 09:12:35AM -0700, Sami Tolvanen wrote:
> This change adds accounting for the memory allocated for shadow stacks.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  drivers/base/node.c    |  6 ++++++
>  fs/proc/meminfo.c      |  4 ++++
>  include/linux/mmzone.h |  3 +++
>  kernel/scs.c           | 20 ++++++++++++++++++++
>  mm/page_alloc.c        |  6 ++++++
>  mm/vmstat.c            |  3 +++
>  6 files changed, 42 insertions(+)
> 
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 10d7e818e118..502ab5447c8d 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -415,6 +415,9 @@ static ssize_t node_read_meminfo(struct device *dev,
>  		       "Node %d AnonPages:      %8lu kB\n"
>  		       "Node %d Shmem:          %8lu kB\n"
>  		       "Node %d KernelStack:    %8lu kB\n"
> +#ifdef CONFIG_SHADOW_CALL_STACK
> +		       "Node %d ShadowCallStack:%8lu kB\n"
> +#endif
>  		       "Node %d PageTables:     %8lu kB\n"
>  		       "Node %d NFS_Unstable:   %8lu kB\n"
>  		       "Node %d Bounce:         %8lu kB\n"
> @@ -438,6 +441,9 @@ static ssize_t node_read_meminfo(struct device *dev,
>  		       nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
>  		       nid, K(i.sharedram),
>  		       nid, sum_zone_node_page_state(nid, NR_KERNEL_STACK_KB),
> +#ifdef CONFIG_SHADOW_CALL_STACK
> +		       nid, sum_zone_node_page_state(nid, NR_KERNEL_SCS_BYTES) / 1024,
> +#endif

Why not just use KB everywhere instead of repeated division by 1024?

Will