Commit 2abf962a authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

PM: hibernate: make direct map manipulations more explicit 

When DEBUG_PAGEALLOC or ARCH_HAS_SET_DIRECT_MAP is enabled a page may be
not present in the direct map and has to be explicitly mapped before it
could be copied.

Introduce hibernate_map_page() and hibernation_unmap_page() that will
explicitly use set_direct_map_{default,invalid}_noflush() for
ARCH_HAS_SET_DIRECT_MAP case and debug_pagealloc_{map,unmap}_pages() for
DEBUG_PAGEALLOC case.

The remapping of the pages in safe_copy_page() presumes that it only
changes protection bits in an existing PTE and so it is safe to ignore
return value of set_direct_map_{default,invalid}_noflush().

Still, add a pr_warn() so that future changes in set_memory APIs will not
silently break hibernation.

Link: https://lkml.kernel.org/r/20201109192128.960-3-rppt@kernel.org


Signed-off-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 77bc7fd6

include/linux/mm.h

+0 −12
Original line number Diff line number Diff line
@@ -2934,16 +2934,6 @@ static inline bool debug_pagealloc_enabled_static(void) 
#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP)

extern void __kernel_map_pages(struct page *page, int numpages, int enable);



/*

 * When called in DEBUG_PAGEALLOC context, the call should most likely be

 * guarded by debug_pagealloc_enabled() or debug_pagealloc_enabled_static()

 */

static inline void

kernel_map_pages(struct page *page, int numpages, int enable)

{

	__kernel_map_pages(page, numpages, enable);

}



static inline void debug_pagealloc_map_pages(struct page *page, int numpages)

{

	if (debug_pagealloc_enabled_static())
@@ -2960,8 +2950,6 @@ static inline void debug_pagealloc_unmap_pages(struct page *page, int numpages) 
extern bool kernel_page_present(struct page *page);

#endif	/* CONFIG_HIBERNATION */

#else	/* CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */

static inline void

kernel_map_pages(struct page *page, int numpages, int enable) {}

static inline void debug_pagealloc_map_pages(struct page *page, int numpages) {}

static inline void debug_pagealloc_unmap_pages(struct page *page, int numpages) {}

#ifdef CONFIG_HIBERNATION

kernel/power/snapshot.c

+36 −2
Original line number Diff line number Diff line
@@ -76,6 +76,40 @@ static inline void hibernate_restore_protect_page(void *page_address) {} 
static inline void hibernate_restore_unprotect_page(void *page_address) {}

#endif /* CONFIG_STRICT_KERNEL_RWX  && CONFIG_ARCH_HAS_SET_MEMORY */





/*

 * The calls to set_direct_map_*() should not fail because remapping a page

 * here means that we only update protection bits in an existing PTE.

 * It is still worth to have a warning here if something changes and this

 * will no longer be the case.

 */

static inline void hibernate_map_page(struct page *page)

{

	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {

		int ret = set_direct_map_default_noflush(page);



		if (ret)

			pr_warn_once("Failed to remap page\n");

	} else {

		debug_pagealloc_map_pages(page, 1);

	}

}



static inline void hibernate_unmap_page(struct page *page)

{

	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {

		unsigned long addr = (unsigned long)page_address(page);

		int ret  = set_direct_map_invalid_noflush(page);



		if (ret)

			pr_warn_once("Failed to remap page\n");



		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);

	} else {

		debug_pagealloc_unmap_pages(page, 1);

	}

}



static int swsusp_page_is_free(struct page *);

static void swsusp_set_page_forbidden(struct page *);

static void swsusp_unset_page_forbidden(struct page *);
@@ -1355,9 +1389,9 @@ static void safe_copy_page(void *dst, struct page *s_page) 
	if (kernel_page_present(s_page)) {

		do_copy_page(dst, page_address(s_page));

	} else {

		kernel_map_pages(s_page, 1, 1);

		hibernate_map_page(s_page);

		do_copy_page(dst, page_address(s_page));

		kernel_map_pages(s_page, 1, 0);

		hibernate_unmap_page(s_page);

	}

}

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