Prepare to reduce dependencies on linux/mm.h. page_kasan_tag() is used by the page_to_virt() macro in ARM64 (but asm/memory.h does not include linux/mm.h). Thus, in order to be able to use anything that calls page_to_virt(), linux/mm.h needs to be included. This would prevent us from moving page_address() to a separate header, because it calls lowmem_page_address() which in turn calls page_to_virt(). To prepare for this move, we move page_kasan_tag() out of linux/mm.h into a separate lean header. A side effect of this patch is that the <linux/kasan.h> include line is moved inside the "#ifdef CONFIG_KASAN..." block, i.e. it is not included at all if KASAN is disabled. Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx> --- MAINTAINERS | 1 + include/linux/mm.h | 56 +------------------------- include/linux/mm/page_kasan_tag.h | 66 +++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+), 55 deletions(-) create mode 100644 include/linux/mm/page_kasan_tag.h diff --git a/MAINTAINERS b/MAINTAINERS index 9e5bb60c55fe..dbfe08329154 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -14210,6 +14210,7 @@ F: include/linux/mempolicy.h F: include/linux/mempool.h F: include/linux/memremap.h F: include/linux/mm.h +F: include/linux/mm/*.h F: include/linux/mm_*.h F: include/linux/mmzone.h F: include/linux/mmu_notifier.h diff --git a/include/linux/mm.h b/include/linux/mm.h index 0436b919f1c7..e140ee45f49c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2,6 +2,7 @@ #ifndef _LINUX_MM_H #define _LINUX_MM_H +#include <linux/mm/page_kasan_tag.h> #include <linux/errno.h> #include <linux/mmdebug.h> #include <linux/gfp.h> @@ -27,7 +28,6 @@ #include <linux/sizes.h> #include <linux/sched.h> #include <linux/pgtable.h> -#include <linux/kasan.h> #include <linux/memremap.h> #include <linux/slab.h> @@ -1818,60 +1818,6 @@ static inline void vma_set_access_pid_bit(struct vm_area_struct *vma) } #endif /* CONFIG_NUMA_BALANCING */ -#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) - -/* - * KASAN per-page tags are stored xor'ed with 0xff. This allows to avoid - * setting tags for all pages to native kernel tag value 0xff, as the default - * value 0x00 maps to 0xff. - */ - -static inline u8 page_kasan_tag(const struct page *page) -{ - u8 tag = KASAN_TAG_KERNEL; - - if (kasan_enabled()) { - tag = (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK; - tag ^= 0xff; - } - - return tag; -} - -static inline void page_kasan_tag_set(struct page *page, u8 tag) -{ - unsigned long old_flags, flags; - - if (!kasan_enabled()) - return; - - tag ^= 0xff; - old_flags = READ_ONCE(page->flags); - do { - flags = old_flags; - flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT); - flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT; - } while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags))); -} - -static inline void page_kasan_tag_reset(struct page *page) -{ - if (kasan_enabled()) - page_kasan_tag_set(page, KASAN_TAG_KERNEL); -} - -#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */ - -static inline u8 page_kasan_tag(const struct page *page) -{ - return 0xff; -} - -static inline void page_kasan_tag_set(struct page *page, u8 tag) { } -static inline void page_kasan_tag_reset(struct page *page) { } - -#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */ - static inline struct zone *page_zone(const struct page *page) { return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]; diff --git a/include/linux/mm/page_kasan_tag.h b/include/linux/mm/page_kasan_tag.h new file mode 100644 index 000000000000..1210c62170a3 --- /dev/null +++ b/include/linux/mm/page_kasan_tag.h @@ -0,0 +1,66 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_MM_PAGE_KASAN_TAG_H +#define _LINUX_MM_PAGE_KASAN_TAG_H + +#include <linux/types.h> + +struct page; + +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) + +#include <linux/kasan.h> +#include <linux/mm_types.h> // for struct page + +/* + * KASAN per-page tags are stored xor'ed with 0xff. This allows to avoid + * setting tags for all pages to native kernel tag value 0xff, as the default + * value 0x00 maps to 0xff. + */ + +static inline u8 page_kasan_tag(const struct page *page) +{ + u8 tag = KASAN_TAG_KERNEL; + + if (kasan_enabled()) { + tag = (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK; + tag ^= 0xff; + } + + return tag; +} + +static inline void page_kasan_tag_set(struct page *page, u8 tag) +{ + unsigned long old_flags, flags; + + if (!kasan_enabled()) + return; + + tag ^= 0xff; + old_flags = READ_ONCE(page->flags); + do { + flags = old_flags; + flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT); + flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT; + } while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags))); +} + +static inline void page_kasan_tag_reset(struct page *page) +{ + if (kasan_enabled()) + page_kasan_tag_set(page, KASAN_TAG_KERNEL); +} + +#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */ + +static inline u8 page_kasan_tag(const struct page *page) +{ + return 0xff; +} + +static inline void page_kasan_tag_set(struct page *page, u8 tag) { } +static inline void page_kasan_tag_reset(struct page *page) { } + +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */ + +#endif /* _LINUX_MM_PAGE_KASAN_TAG_H */ -- 2.39.2