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authorTony Luck <tony.luck@intel.com>2017-08-16 20:18:03 +0300
committerIngo Molnar <mingo@kernel.org>2017-08-17 11:30:49 +0300
commitce0fa3e56ad20f04d8252353dcd24e924abdafca (patch)
treedee3cdb69e839f4eb1dc5690deb7e145202124c7 /include/linux/mm_inline.h
parent57bd1905b228f2a14d7506b0302f69f425131e57 (diff)
downloadlinux-ce0fa3e56ad20f04d8252353dcd24e924abdafca.tar.xz
x86/mm, mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages
Speculative processor accesses may reference any memory that has a valid page table entry. While a speculative access won't generate a machine check, it will log the error in a machine check bank. That could cause escalation of a subsequent error since the overflow bit will be then set in the machine check bank status register. Code has to be double-plus-tricky to avoid mentioning the 1:1 virtual address of the page we want to map out otherwise we may trigger the very problem we are trying to avoid. We use a non-canonical address that passes through the usual Linux table walking code to get to the same "pte". Thanks to Dave Hansen for reviewing several iterations of this. Also see: http://marc.info/?l=linux-mm&m=149860136413338&w=2 Signed-off-by: Tony Luck <tony.luck@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Elliott, Robert (Persistent Memory) <elliott@hpe.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20170816171803.28342-1-tony.luck@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/mm_inline.h')
-rw-r--r--include/linux/mm_inline.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index e030a68ead7e..25438b2b6f22 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -126,4 +126,10 @@ static __always_inline enum lru_list page_lru(struct page *page)
#define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
+#ifdef arch_unmap_kpfn
+extern void arch_unmap_kpfn(unsigned long pfn);
+#else
+static __always_inline void arch_unmap_kpfn(unsigned long pfn) { }
+#endif
+
#endif