diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-09-20 05:09:58 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-09-29 17:20:46 -0700 |
| commit | ce60f27bb62dfeb1bf827350520f34abc84e0933 (patch) | |
| tree | ba2bb32d49a6ed1df73a1f1e62392929b12c5e1f | |
| parent | a501a0703044f00180d7697b32cacd7ff46d02d8 (diff) | |
mm: abstract moving to the next PFN
In order to fix the L1TF vulnerability, x86 can invert the PTE bits for
PROT_NONE VMAs, which means we cannot move from one PTE to the next by
adding 1 to the PFN field of the PTE. This results in the BUG reported at
[1].
Abstract advancing the PTE to the next PFN through a pte_next_pfn()
function/macro.
Link: https://lkml.kernel.org/r/20230920040958.866520-1-willy@infradead.org
Fixes: bcc6cc832573 ("mm: add default definition of set_ptes()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: syzbot+55cc72f8cc3a549119df@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/000000000000d099fa0604f03351@google.com [1]
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | arch/x86/include/asm/pgtable.h | 8 | ||||
| -rw-r--r-- | include/linux/pgtable.h | 10 |
2 files changed, 17 insertions, 1 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index d6ad98ca1288..e02b179ec659 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -955,6 +955,14 @@ static inline int pte_same(pte_t a, pte_t b) return a.pte == b.pte; } +static inline pte_t pte_next_pfn(pte_t pte) +{ + if (__pte_needs_invert(pte_val(pte))) + return __pte(pte_val(pte) - (1UL << PFN_PTE_SHIFT)); + return __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT)); +} +#define pte_next_pfn pte_next_pfn + static inline int pte_present(pte_t a) { return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE); diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 1fba072b3dac..af7639c3b0a3 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -206,6 +206,14 @@ static inline int pmd_young(pmd_t pmd) #endif #ifndef set_ptes + +#ifndef pte_next_pfn +static inline pte_t pte_next_pfn(pte_t pte) +{ + return __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT)); +} +#endif + /** * set_ptes - Map consecutive pages to a contiguous range of addresses. * @mm: Address space to map the pages into. @@ -231,7 +239,7 @@ static inline void set_ptes(struct mm_struct *mm, unsigned long addr, if (--nr == 0) break; ptep++; - pte = __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT)); + pte = pte_next_pfn(pte); } arch_leave_lazy_mmu_mode(); } |