Messages in this thread | | | From | Kees Cook <> | Date | Fri, 12 Aug 2016 11:06:14 -0700 | Subject | Re: [PATCH v3] ARM: VDSO: put RO and RO after init objects into proper sections |
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On Fri, Aug 12, 2016 at 1:12 AM, Jisheng Zhang <jszhang@marvell.com> wrote: > vdso_data_mapping is never modified, so mark it as const. > > vdso_total_pages, vdso_data_page, vdso_text_mapping and cntvct_ok are > initialized by vdso_init(), thereafter are read only. > > The fact that they are read only after init makes them candidates for > __ro_after_init declarations. > > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Looks great; thanks for keeping __ro_after_init in mind. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> --- > > Since v2: > - include <linux/cache.h> explicitly for __ro_after_init > > Since v1: > - use __ro_after_init instead of __read_mostly > - apply __ro_after_init for vdso_total_pages and cntvct_ok as well > > arch/arm/kernel/vdso.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c > index 994e971..bbbffe94 100644 > --- a/arch/arm/kernel/vdso.c > +++ b/arch/arm/kernel/vdso.c > @@ -17,6 +17,7 @@ > * along with this program. If not, see <http://www.gnu.org/licenses/>. > */ > > +#include <linux/cache.h> > #include <linux/elf.h> > #include <linux/err.h> > #include <linux/kernel.h> > @@ -39,7 +40,7 @@ > static struct page **vdso_text_pagelist; > > /* Total number of pages needed for the data and text portions of the VDSO. */ > -unsigned int vdso_total_pages __read_mostly; > +unsigned int vdso_total_pages __ro_after_init; > > /* > * The VDSO data page. > @@ -47,13 +48,13 @@ unsigned int vdso_total_pages __read_mostly; > static union vdso_data_store vdso_data_store __page_aligned_data; > static struct vdso_data *vdso_data = &vdso_data_store.data; > > -static struct page *vdso_data_page; > -static struct vm_special_mapping vdso_data_mapping = { > +static struct page *vdso_data_page __ro_after_init; > +static const struct vm_special_mapping vdso_data_mapping = { > .name = "[vvar]", > .pages = &vdso_data_page, > }; > > -static struct vm_special_mapping vdso_text_mapping = { > +static struct vm_special_mapping vdso_text_mapping __ro_after_init = { > .name = "[vdso]", > }; > > @@ -67,7 +68,7 @@ struct elfinfo { > /* Cached result of boot-time check for whether the arch timer exists, > * and if so, whether the virtual counter is useable. > */ > -static bool cntvct_ok __read_mostly; > +static bool cntvct_ok __ro_after_init; > > static bool __init cntvct_functional(void) > { > -- > 2.8.1 >
-- Kees Cook Nexus Security
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