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From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
	Andy Lutomirski <luto@kernel.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Borislav Petkov <bp@alien8.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Christoph Lameter <cl@linux.com>,
	"David S. Miller" <davem@davemloft.net>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	David Hildenbrand <david@redhat.com>,
	David Rientjes <rientjes@google.com>,
	"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Len Brown <len.brown@intel.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Mike Rapoport <rppt@kernel.org>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Pavel Machek <pavel@ucw.cz>, Pekka Enberg <penberg@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vasily Gorbik <gor@linux.ibm.com>, Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-pm@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	sparclinux@vger.kernel.org, x86@kernel.org
Subject: [PATCH v2 2/4] PM: hibernate: make direct map manipulations more explicit
Date: Thu, 29 Oct 2020 18:19:00 +0200	[thread overview]
Message-ID: <20201029161902.19272-3-rppt@kernel.org> (raw)
In-Reply-To: <20201029161902.19272-1-rppt@kernel.org>

From: Mike Rapoport <rppt@linux.ibm.com>

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.

On arm64 it is possible that a page would be removed from the direct map
using set_direct_map_invalid_noflush() but __kernel_map_pages() will refuse
to map this page back if DEBUG_PAGEALLOC is disabled.

Introduce hibernate_map_page() that will explicitly use
set_direct_map_{default,invalid}_noflush() for ARCH_HAS_SET_DIRECT_MAP case
and debug_pagealloc_map_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 WARN_ON() so that future changes in set_memory APIs will not
silently break hibernation.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 include/linux/mm.h      | 12 ------------
 kernel/power/snapshot.c | 30 ++++++++++++++++++++++++++++--
 2 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1fc0609056dc..14e397f3752c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2927,16 +2927,6 @@ 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, int enable)
 {
@@ -2948,8 +2938,6 @@ static inline void debug_pagealloc_map_pages(struct page *page,
 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, int enable) {}
 #ifdef CONFIG_HIBERNATION
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 46b1804c1ddf..054c8cce4236 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -76,6 +76,32 @@ 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 */
 
+static inline void hibernate_map_page(struct page *page, int enable)
+{
+	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
+		unsigned long addr = (unsigned long)page_address(page);
+		int ret;
+
+		/*
+		 * This 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 WARN_ON() here if something
+		 * changes and this will no longer be the case.
+		 */
+		if (enable)
+			ret = set_direct_map_default_noflush(page);
+		else
+			ret = set_direct_map_invalid_noflush(page);
+
+		if (WARN_ON(ret))
+			return;
+
+		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+	} else {
+		debug_pagealloc_map_pages(page, 1, enable);
+	}
+}
+
 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 +1381,9 @@ 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, 1);
 		do_copy_page(dst, page_address(s_page));
-		kernel_map_pages(s_page, 1, 0);
+		hibernate_map_page(s_page, 0);
 	}
 }
 
-- 
2.28.0


  parent reply	other threads:[~2020-10-29 16:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-29 16:18 [PATCH v2 0/4] arch, mm: improve robustness of direct map manipulation Mike Rapoport
2020-10-29 16:18 ` [PATCH v2 1/4] mm: introduce debug_pagealloc_map_pages() helper Mike Rapoport
2020-10-29 16:19 ` Mike Rapoport [this message]
2020-10-29 16:30   ` [PATCH v2 2/4] PM: hibernate: make direct map manipulations more explicit Rafael J. Wysocki
2020-10-29 16:19 ` [PATCH v2 3/4] arch, mm: restore dependency of __kernel_map_pages() of DEBUG_PAGEALLOC Mike Rapoport
2020-10-29 16:19 ` [PATCH v2 4/4] arch, mm: make kernel_page_present() always available Mike Rapoport

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