| Message ID | 1518083420-11108-4-git-send-email-wei.w.wang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Feb 08, 2018 at 05:50:19PM +0800, Wei Wang wrote: > Move the PAGE_POISON value to page_poison.c and add a function to enable > callers from a kernel module to get the poison value if the page poisoning > feature is in use. This also avoids callers directly checking PAGE_POISON > regardless of whether the feature is enabled. > > Signed-off-by: Wei Wang <wei.w.wang@intel.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Michael S. Tsirkin <mst@redhat.com> > --- > include/linux/mm.h | 2 ++ > include/linux/poison.h | 7 ------- > mm/page_poison.c | 24 ++++++++++++++++++++++++ > 3 files changed, 26 insertions(+), 7 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 1c77d88..d95e5d3 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2469,11 +2469,13 @@ extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, > extern bool page_poisoning_enabled(void); > extern void kernel_poison_pages(struct page *page, int numpages, int enable); > extern bool page_is_poisoned(struct page *page); > +extern bool page_poison_val_get(u8 *val); > #else > static inline bool page_poisoning_enabled(void) { return false; } > static inline void kernel_poison_pages(struct page *page, int numpages, > int enable) { } > static inline bool page_is_poisoned(struct page *page) { return false; } > +static inline bool page_poison_val_get(u8 *val) { return false; }; > #endif > > #ifdef CONFIG_DEBUG_PAGEALLOC Thinking more about it, page_poisoning_enabled already exists. I would just add "u8 page_poison_val_get(void)" and don't add a stub since compiler will drop the call with poisoning off. > diff --git a/include/linux/poison.h b/include/linux/poison.h > index 15927eb..348bf67 100644 > --- a/include/linux/poison.h > +++ b/include/linux/poison.h > @@ -30,13 +30,6 @@ > */ > #define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA) > > -/********** mm/debug-pagealloc.c **********/ > -#ifdef CONFIG_PAGE_POISONING_ZERO > -#define PAGE_POISON 0x00 > -#else > -#define PAGE_POISON 0xaa > -#endif > - > /********** mm/page_alloc.c ************/ > I'd split this chunk out, this patchset is at v28 as it is. > #define TAIL_MAPPING ((void *) 0x400 + POISON_POINTER_DELTA) > diff --git a/mm/page_poison.c b/mm/page_poison.c > index e83fd44..9a07973 100644 > --- a/mm/page_poison.c > +++ b/mm/page_poison.c > @@ -7,6 +7,13 @@ > #include <linux/poison.h> > #include <linux/ratelimit.h> > > +/********** mm/debug-pagealloc.c **********/ This file no longer exists. > +#ifdef CONFIG_PAGE_POISONING_ZERO > +#define PAGE_POISON 0x00 > +#else > +#define PAGE_POISON 0xaa > +#endif > + > static bool want_page_poisoning __read_mostly; > > static int early_page_poison_param(char *buf) > @@ -30,6 +37,23 @@ bool page_poisoning_enabled(void) > debug_pagealloc_enabled())); > } > > +/** > + * page_poison_val_get - get the page poison value if page poisoning is enabled > + * @val: the caller's memory to get the page poison value > + * > + * Return true with @val stores the poison value if page poisoning is enabled. > + * Otherwise, return false with @val unchanged. > + */ > +bool page_poison_val_get(u8 *val) > +{ > + if (!page_poisoning_enabled()) > + return false; > + > + *val = PAGE_POISON; > + return true; > +} > +EXPORT_SYMBOL_GPL(page_poison_val_get); > + > static void poison_page(struct page *page) > { > void *addr = kmap_atomic(page); > -- > 2.7.4
diff --git a/include/linux/mm.h b/include/linux/mm.h index 1c77d88..d95e5d3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2469,11 +2469,13 @@ extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, extern bool page_poisoning_enabled(void); extern void kernel_poison_pages(struct page *page, int numpages, int enable); extern bool page_is_poisoned(struct page *page); +extern bool page_poison_val_get(u8 *val); #else static inline bool page_poisoning_enabled(void) { return false; } static inline void kernel_poison_pages(struct page *page, int numpages, int enable) { } static inline bool page_is_poisoned(struct page *page) { return false; } +static inline bool page_poison_val_get(u8 *val) { return false; }; #endif #ifdef CONFIG_DEBUG_PAGEALLOC diff --git a/include/linux/poison.h b/include/linux/poison.h index 15927eb..348bf67 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -30,13 +30,6 @@ */ #define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA) -/********** mm/debug-pagealloc.c **********/ -#ifdef CONFIG_PAGE_POISONING_ZERO -#define PAGE_POISON 0x00 -#else -#define PAGE_POISON 0xaa -#endif - /********** mm/page_alloc.c ************/ #define TAIL_MAPPING ((void *) 0x400 + POISON_POINTER_DELTA) diff --git a/mm/page_poison.c b/mm/page_poison.c index e83fd44..9a07973 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -7,6 +7,13 @@ #include <linux/poison.h> #include <linux/ratelimit.h> +/********** mm/debug-pagealloc.c **********/ +#ifdef CONFIG_PAGE_POISONING_ZERO +#define PAGE_POISON 0x00 +#else +#define PAGE_POISON 0xaa +#endif + static bool want_page_poisoning __read_mostly; static int early_page_poison_param(char *buf) @@ -30,6 +37,23 @@ bool page_poisoning_enabled(void) debug_pagealloc_enabled())); } +/** + * page_poison_val_get - get the page poison value if page poisoning is enabled + * @val: the caller's memory to get the page poison value + * + * Return true with @val stores the poison value if page poisoning is enabled. + * Otherwise, return false with @val unchanged. + */ +bool page_poison_val_get(u8 *val) +{ + if (!page_poisoning_enabled()) + return false; + + *val = PAGE_POISON; + return true; +} +EXPORT_SYMBOL_GPL(page_poison_val_get); + static void poison_page(struct page *page) { void *addr = kmap_atomic(page);
Move the PAGE_POISON value to page_poison.c and add a function to enable callers from a kernel module to get the poison value if the page poisoning feature is in use. This also avoids callers directly checking PAGE_POISON regardless of whether the feature is enabled. Signed-off-by: Wei Wang <wei.w.wang@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> --- include/linux/mm.h | 2 ++ include/linux/poison.h | 7 ------- mm/page_poison.c | 24 ++++++++++++++++++++++++ 3 files changed, 26 insertions(+), 7 deletions(-)