From: Sergey Dyasli <sergey.dyasli@citrix.com>
To: <xen-devel@lists.xen.org>, <kasan-dev@googlegroups.com>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
George Dunlap <george.dunlap@citrix.com>,
Ross Lagerwall <ross.lagerwall@citrix.com>,
Andrew Morton <akpm@linux-foundation.org>,
Sergey Dyasli <sergey.dyasli@citrix.com>
Subject: [PATCH v2 1/4] kasan: introduce set_pmd_early_shadow()
Date: Fri, 17 Jan 2020 12:58:31 +0000 [thread overview]
Message-ID: <20200117125834.14552-2-sergey.dyasli@citrix.com> (raw)
In-Reply-To: <20200117125834.14552-1-sergey.dyasli@citrix.com>
It is incorrect to call pmd_populate_kernel() multiple times for the
same page table from inside Xen PV domains. Xen notices it during
kasan_populate_early_shadow():
(XEN) mm.c:3222:d155v0 mfn 3704b already pinned
This happens for kasan_early_shadow_pte when USE_SPLIT_PTE_PTLOCKS is
enabled. Fix this by introducing set_pmd_early_shadow() which calls
pmd_populate_kernel() only once and uses set_pmd() afterwards.
Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
---
v1 --> v2:
- Fix compilation without CONFIG_XEN_PV
- Slightly updated description
RFC --> v1:
- New patch
---
mm/kasan/init.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)
diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index ce45c491ebcd..7791fe0a7704 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -81,6 +81,26 @@ static inline bool kasan_early_shadow_page_entry(pte_t pte)
return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
}
+#ifdef CONFIG_XEN_PV
+static inline void set_pmd_early_shadow(pmd_t *pmd)
+{
+ static bool pmd_populated = false;
+ pte_t *early_shadow = lm_alias(kasan_early_shadow_pte);
+
+ if (likely(pmd_populated)) {
+ set_pmd(pmd, __pmd(__pa(early_shadow) | _PAGE_TABLE));
+ } else {
+ pmd_populate_kernel(&init_mm, pmd, early_shadow);
+ pmd_populated = true;
+ }
+}
+#else
+static inline void set_pmd_early_shadow(pmd_t *pmd)
+{
+ pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_early_shadow_pte));
+}
+#endif /* ifdef CONFIG_XEN_PV */
+
static __init void *early_alloc(size_t size, int node)
{
void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
@@ -120,8 +140,7 @@ static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
next = pmd_addr_end(addr, end);
if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
- pmd_populate_kernel(&init_mm, pmd,
- lm_alias(kasan_early_shadow_pte));
+ set_pmd_early_shadow(pmd);
continue;
}
@@ -157,8 +176,7 @@ static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
pud_populate(&init_mm, pud,
lm_alias(kasan_early_shadow_pmd));
pmd = pmd_offset(pud, addr);
- pmd_populate_kernel(&init_mm, pmd,
- lm_alias(kasan_early_shadow_pte));
+ set_pmd_early_shadow(pmd);
continue;
}
@@ -198,8 +216,7 @@ static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
pud_populate(&init_mm, pud,
lm_alias(kasan_early_shadow_pmd));
pmd = pmd_offset(pud, addr);
- pmd_populate_kernel(&init_mm, pmd,
- lm_alias(kasan_early_shadow_pte));
+ set_pmd_early_shadow(pmd);
continue;
}
@@ -271,8 +288,7 @@ int __ref kasan_populate_early_shadow(const void *shadow_start,
pud_populate(&init_mm, pud,
lm_alias(kasan_early_shadow_pmd));
pmd = pmd_offset(pud, addr);
- pmd_populate_kernel(&init_mm, pmd,
- lm_alias(kasan_early_shadow_pte));
+ set_pmd_early_shadow(pmd);
continue;
}
--
2.17.1
next prev parent reply other threads:[~2020-01-17 12:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-17 12:58 [PATCH v2 0/4] basic KASAN support for Xen PV domains Sergey Dyasli
2020-01-17 12:58 ` Sergey Dyasli [this message]
2020-01-17 12:58 ` [PATCH v2 2/4] x86/xen: add basic KASAN support for PV kernel Sergey Dyasli
2020-01-17 14:56 ` Boris Ostrovsky
2020-01-22 11:13 ` Sergey Dyasli
2020-01-21 14:54 ` kbuild test robot
2020-01-21 16:25 ` kbuild test robot
2020-01-17 12:58 ` [PATCH v2 3/4] xen: teach KASAN about grant tables Sergey Dyasli
2020-01-17 12:58 ` [PATCH v2 4/4] xen/netback: fix grant copy across page boundary Sergey Dyasli
2020-01-20 8:58 ` Paul Durrant
2020-01-22 10:07 ` Sergey Dyasli
2020-01-22 14:05 ` Wei Liu
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