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Date: Wed, 7 Jun 2017 15:16:53 -0600
From: Tycho Andersen <tycho@...ker.com>
To: linux-mm@...ck.org
Cc: Juerg Haefliger <juergh@...il.com>,
kernel-hardening@...ts.openwall.com,
Tycho Andersen <tycho@...ker.com>
Subject: [RFC v4 3/3] xpfo: add support for hugepages
Based on an earlier draft by Marco Benatto.
Signed-off-by: Tycho Andersen <tycho@...ker.com>
CC: Juerg Haefliger <juergh@...il.com>
---
arch/x86/include/asm/pgtable.h | 22 +++++++++++++++
arch/x86/mm/pageattr.c | 21 +++------------
arch/x86/mm/xpfo.c | 61 +++++++++++++++++++++++++++++++++++++++++-
include/linux/xpfo.h | 1 +
mm/xpfo.c | 8 ++----
5 files changed, 88 insertions(+), 25 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index f5af95a0c6b8..58bb43d8b9c1 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1185,6 +1185,28 @@ static inline u16 pte_flags_pkey(unsigned long pte_flags)
#endif
}
+/*
+ * The current flushing context - we pass it instead of 5 arguments:
+ */
+struct cpa_data {
+ unsigned long *vaddr;
+ pgd_t *pgd;
+ pgprot_t mask_set;
+ pgprot_t mask_clr;
+ unsigned long numpages;
+ int flags;
+ unsigned long pfn;
+ unsigned force_split : 1;
+ int curpage;
+ struct page **pages;
+};
+
+int
+try_preserve_large_page(pte_t *kpte, unsigned long address,
+ struct cpa_data *cpa);
+int split_large_page(struct cpa_data *cpa, pte_t *kpte,
+ unsigned long address);
+
#include <asm-generic/pgtable.h>
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 1dcd2be4cce4..6d6a78e6e023 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -26,21 +26,6 @@
#include <asm/pat.h>
#include <asm/set_memory.h>
-/*
- * The current flushing context - we pass it instead of 5 arguments:
- */
-struct cpa_data {
- unsigned long *vaddr;
- pgd_t *pgd;
- pgprot_t mask_set;
- pgprot_t mask_clr;
- unsigned long numpages;
- int flags;
- unsigned long pfn;
- unsigned force_split : 1;
- int curpage;
- struct page **pages;
-};
/*
* Serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings)
@@ -506,7 +491,7 @@ static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
#endif
}
-static int
+int
try_preserve_large_page(pte_t *kpte, unsigned long address,
struct cpa_data *cpa)
{
@@ -740,8 +725,8 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
return 0;
}
-static int split_large_page(struct cpa_data *cpa, pte_t *kpte,
- unsigned long address)
+int split_large_page(struct cpa_data *cpa, pte_t *kpte,
+ unsigned long address)
{
struct page *base;
diff --git a/arch/x86/mm/xpfo.c b/arch/x86/mm/xpfo.c
index c24b06c9b4ab..818da3ebc077 100644
--- a/arch/x86/mm/xpfo.c
+++ b/arch/x86/mm/xpfo.c
@@ -13,11 +13,70 @@
#include <linux/mm.h>
+#include <asm/tlbflush.h>
+
/* Update a single kernel page table entry */
inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot)
{
unsigned int level;
pte_t *pte = lookup_address((unsigned long)kaddr, &level);
- set_pte_atomic(pte, pfn_pte(page_to_pfn(page), canon_pgprot(prot)));
+
+ BUG_ON(!pte);
+
+ switch (level) {
+ case PG_LEVEL_4K:
+ set_pte_atomic(pte, pfn_pte(page_to_pfn(page), canon_pgprot(prot)));
+ break;
+ case PG_LEVEL_2M:
+ case PG_LEVEL_1G: {
+ struct cpa_data cpa;
+ int do_split;
+
+ memset(&cpa, 0, sizeof(cpa));
+ cpa.vaddr = kaddr;
+ cpa.pages = &page;
+ cpa.mask_set = prot;
+ pgprot_val(cpa.mask_clr) = ~pgprot_val(prot);
+ cpa.numpages = 1;
+ cpa.flags = 0;
+ cpa.curpage = 0;
+ cpa.force_split = 0;
+
+ do_split = try_preserve_large_page(pte, (unsigned long)kaddr, &cpa);
+ if (do_split < 0)
+ BUG_ON(split_large_page(&cpa, pte, (unsigned long)kaddr));
+
+ break;
+ }
+ default:
+ BUG();
+ }
+
+}
+
+inline void xpfo_flush_kernel_page(struct page *page, int order)
+{
+ int level;
+ unsigned long size, kaddr;
+
+ kaddr = (unsigned long)page_address(page);
+ lookup_address(kaddr, &level);
+
+
+ switch (level) {
+ case PG_LEVEL_4K:
+ size = PAGE_SIZE;
+ break;
+ case PG_LEVEL_2M:
+ size = PMD_SIZE;
+ break;
+ case PG_LEVEL_1G:
+ size = PUD_SIZE;
+ break;
+ default:
+ BUG();
+ }
+
+ flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size);
}
diff --git a/include/linux/xpfo.h b/include/linux/xpfo.h
index 031cbee22a41..a0f0101720f6 100644
--- a/include/linux/xpfo.h
+++ b/include/linux/xpfo.h
@@ -19,6 +19,7 @@
extern struct page_ext_operations page_xpfo_ops;
void set_kpte(void *kaddr, struct page *page, pgprot_t prot);
+void xpfo_flush_kernel_page(struct page *page, int order);
void xpfo_kmap(void *kaddr, struct page *page);
void xpfo_kunmap(void *kaddr, struct page *page);
diff --git a/mm/xpfo.c b/mm/xpfo.c
index 8384058136b1..895de28108da 100644
--- a/mm/xpfo.c
+++ b/mm/xpfo.c
@@ -78,7 +78,6 @@ void xpfo_alloc_pages(struct page *page, int order, gfp_t gfp)
{
int i, flush_tlb = 0;
struct xpfo *xpfo;
- unsigned long kaddr;
if (!static_branch_unlikely(&xpfo_inited))
return;
@@ -109,11 +108,8 @@ void xpfo_alloc_pages(struct page *page, int order, gfp_t gfp)
}
}
- if (flush_tlb) {
- kaddr = (unsigned long)page_address(page);
- flush_tlb_kernel_range(kaddr, kaddr + (1 << order) *
- PAGE_SIZE);
- }
+ if (flush_tlb)
+ xpfo_flush_kernel_page(page, order);
}
void xpfo_free_pages(struct page *page, int order)
--
2.11.0
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