linux-kernel - [PATCH 2/4] mm/kasan: Move kasan_pXX_table() and kasan_early_shadow_page

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Date:   Wed, 2 Feb 2022 08:44:58 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Christophe Leroy <christophe.leroy@...roup.eu>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
        "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>
Subject: [PATCH 2/4] mm/kasan: Move kasan_pXX_table() and
 kasan_early_shadow_page_entry()

In order to reuse them outside of mm/kasan/init.c, move the
following helpers outside of init.c:

	kasan_p4d_table()
	kasan_pud_table()
	kasan_pmd_table()
	kasan_pte_table()
	kasan_early_shadow_page_entry()

And make them available when KASAN is not selected.

Inclusion of kasan.h in mm.h needs to be moved down a bit
in order to get lm_alias() definition.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 include/linux/kasan.h | 57 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/mm.h    |  3 ++-
 mm/kasan/init.c       | 37 ----------------------------
 3 files changed, 59 insertions(+), 38 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index c29778b25d8a..1629797198ec 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -28,6 +28,7 @@ struct kunit_kasan_expectation {
 #ifdef CONFIG_KASAN_SOFTWARE
 
 #include <linux/pgtable.h>
+#include <linux/mm.h>
 
 /* Software KASAN implementations use shadow memory. */
 
@@ -81,6 +82,62 @@ static inline void kasan_disable_current(void) {}
 
 #endif /* CONFIG_KASAN_SOFTWARE */
 
+#if defined(CONFIG_KASAN_SOFTWARE) && CONFIG_PGTABLE_LEVELS > 4
+static inline bool kasan_p4d_table(pgd_t pgd)
+{
+	return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
+}
+#else
+static inline bool kasan_p4d_table(pgd_t pgd)
+{
+	return false;
+}
+#endif
+#if defined(CONFIG_KASAN_SOFTWARE) && CONFIG_PGTABLE_LEVELS > 3
+static inline bool kasan_pud_table(p4d_t p4d)
+{
+	return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
+}
+#else
+static inline bool kasan_pud_table(p4d_t p4d)
+{
+	return false;
+}
+#endif
+#if defined(CONFIG_KASAN_SOFTWARE) && CONFIG_PGTABLE_LEVELS > 2
+static inline bool kasan_pmd_table(pud_t pud)
+{
+	return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
+}
+#else
+static inline bool kasan_pmd_table(pud_t pud)
+{
+	return false;
+}
+#endif
+
+#ifdef CONFIG_KASAN_SOFTWARE
+static inline bool kasan_pte_table(pmd_t pmd)
+{
+	return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
+}
+
+static inline bool kasan_early_shadow_page_entry(pte_t pte)
+{
+	return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
+}
+#else
+static inline bool kasan_pte_table(pmd_t pmd)
+{
+	return false;
+}
+
+static inline bool kasan_early_shadow_page_entry(pte_t pte)
+{
+	return false;
+}
+#endif
+
 #ifdef CONFIG_KASAN_HW_TAGS
 
 DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e1a84b1e6787..b06ee84b3717 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -31,7 +31,6 @@
 #include <linux/sizes.h>
 #include <linux/sched.h>
 #include <linux/pgtable.h>
-#include <linux/kasan.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -121,6 +120,8 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #define lm_alias(x)	__va(__pa_symbol(x))
 #endif
 
+#include <linux/kasan.h>
+
 /*
  * To prevent common memory management code establishing
  * a zero page mapping on a read fault.
diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index cc64ed6858c6..e863071a49ef 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -30,53 +30,16 @@ unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
 
 #if CONFIG_PGTABLE_LEVELS > 4
 p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
-static inline bool kasan_p4d_table(pgd_t pgd)
-{
-	return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
-}
-#else
-static inline bool kasan_p4d_table(pgd_t pgd)
-{
-	return false;
-}
 #endif
 #if CONFIG_PGTABLE_LEVELS > 3
 pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss;
-static inline bool kasan_pud_table(p4d_t p4d)
-{
-	return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
-}
-#else
-static inline bool kasan_pud_table(p4d_t p4d)
-{
-	return false;
-}
 #endif
 #if CONFIG_PGTABLE_LEVELS > 2
 pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss;
-static inline bool kasan_pmd_table(pud_t pud)
-{
-	return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
-}
-#else
-static inline bool kasan_pmd_table(pud_t pud)
-{
-	return false;
-}
 #endif
 pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
 	__page_aligned_bss;
 
-static inline bool kasan_pte_table(pmd_t pmd)
-{
-	return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
-}
-
-static inline bool kasan_early_shadow_page_entry(pte_t pte)
-{
-	return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
-}
-
 static __init void *early_alloc(size_t size, int node)
 {
 	void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
-- 
2.33.1