| Message ID | 1470989538-2953-1-git-send-email-jszhang@marvell.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 >
On 08/12/2016 01:06 PM, Kees Cook wrote: > 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> Looks fine and nothing goes wrong with my vdso tests. Please send it through Russell. Acked-by: Nathan Lynch <nathan_lynch@mentor.com>
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) {
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> --- 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(-)