| Message ID | 20200324203231.64324-3-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Optionally randomize kernel stack offset each syscall | expand |
On Tue, Mar 24, 2020 at 9:32 PM Kees Cook <keescook@chromium.org> wrote: > > Right now, the state of CONFIG_INIT_ON_ALLOC_DEFAULT_ON (and > ...ON_FREE...) did not change the assembly ordering of the static branch > tests. Use the new jump_label macro to check CONFIG settings to default > to the "expected" state, unpessimizes the resulting assembly code. > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > include/linux/mm.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 059658604dd6..64e911159ffa 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2665,7 +2665,8 @@ static inline void kernel_poison_pages(struct page *page, int numpages, > DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc); > static inline bool want_init_on_alloc(gfp_t flags) > { > - if (static_branch_unlikely(&init_on_alloc) && > + if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, > + &init_on_alloc) && > !page_poisoning_enabled()) > return true; > return flags & __GFP_ZERO; > @@ -2674,7 +2675,8 @@ static inline bool want_init_on_alloc(gfp_t flags) > DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free); > static inline bool want_init_on_free(void) > { > - return static_branch_unlikely(&init_on_free) && > + return static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON, > + &init_on_free) && > !page_poisoning_enabled(); > } > > -- > 2.20.1 > Reviewed-by: Alexander Potapenko <glider@google.com>
diff --git a/include/linux/mm.h b/include/linux/mm.h index 059658604dd6..64e911159ffa 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2665,7 +2665,8 @@ static inline void kernel_poison_pages(struct page *page, int numpages, DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc); static inline bool want_init_on_alloc(gfp_t flags) { - if (static_branch_unlikely(&init_on_alloc) && + if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, + &init_on_alloc) && !page_poisoning_enabled()) return true; return flags & __GFP_ZERO; @@ -2674,7 +2675,8 @@ static inline bool want_init_on_alloc(gfp_t flags) DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free); static inline bool want_init_on_free(void) { - return static_branch_unlikely(&init_on_free) && + return static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON, + &init_on_free) && !page_poisoning_enabled(); }
Right now, the state of CONFIG_INIT_ON_ALLOC_DEFAULT_ON (and ...ON_FREE...) did not change the assembly ordering of the static branch tests. Use the new jump_label macro to check CONFIG settings to default to the "expected" state, unpessimizes the resulting assembly code. Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/mm.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)