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From: Alexandre Ghiti <alexghiti@rivosinc.com>
To: Russell King <linux@armlinux.org.uk>,
	Ryan Roberts <ryan.roberts@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Anup Patel <anup@brainfault.org>,
	Atish Patra <atishp@atishpatra.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	kasan-dev@googlegroups.com, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	kvm-riscv@lists.infradead.org, linux-efi@vger.kernel.org,
	linux-mm@kvack.org
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Subject: [PATCH v2 1/4] riscv: Use WRITE_ONCE() when setting page table entries
Date: Wed, 13 Dec 2023 21:29:58 +0100	[thread overview]
Message-ID: <20231213203001.179237-2-alexghiti@rivosinc.com> (raw)
In-Reply-To: <20231213203001.179237-1-alexghiti@rivosinc.com>

To avoid any compiler "weirdness" when accessing page table entries which
are concurrently modified by the HW, let's use WRITE_ONCE() macro
(commit 20a004e7b017 ("arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing
page tables") gives a great explanation with more details).

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/include/asm/pgtable-64.h | 6 +++---
 arch/riscv/include/asm/pgtable.h    | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 9a2c780a11e9..5d8431a390dd 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -202,7 +202,7 @@ static inline int pud_user(pud_t pud)
 
 static inline void set_pud(pud_t *pudp, pud_t pud)
 {
-	*pudp = pud;
+	WRITE_ONCE(*pudp, pud);
 }
 
 static inline void pud_clear(pud_t *pudp)
@@ -278,7 +278,7 @@ static inline unsigned long _pmd_pfn(pmd_t pmd)
 static inline void set_p4d(p4d_t *p4dp, p4d_t p4d)
 {
 	if (pgtable_l4_enabled)
-		*p4dp = p4d;
+		WRITE_ONCE(*p4dp, p4d);
 	else
 		set_pud((pud_t *)p4dp, (pud_t){ p4d_val(p4d) });
 }
@@ -351,7 +351,7 @@ static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
 static inline void set_pgd(pgd_t *pgdp, pgd_t pgd)
 {
 	if (pgtable_l5_enabled)
-		*pgdp = pgd;
+		WRITE_ONCE(*pgdp, pgd);
 	else
 		set_p4d((p4d_t *)pgdp, (p4d_t){ pgd_val(pgd) });
 }
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 294044429e8e..c9f4b250b4ee 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -248,7 +248,7 @@ static inline int pmd_leaf(pmd_t pmd)
 
 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
-	*pmdp = pmd;
+	WRITE_ONCE(*pmdp, pmd);
 }
 
 static inline void pmd_clear(pmd_t *pmdp)
@@ -510,7 +510,7 @@ static inline int pte_same(pte_t pte_a, pte_t pte_b)
  */
 static inline void set_pte(pte_t *ptep, pte_t pteval)
 {
-	*ptep = pteval;
+	WRITE_ONCE(*ptep, pteval);
 }
 
 void flush_icache_pte(pte_t pte);
-- 
2.39.2


WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Ghiti <alexghiti@rivosinc.com>
To: Russell King <linux@armlinux.org.uk>,
	Ryan Roberts <ryan.roberts@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Anup Patel <anup@brainfault.org>,
	Atish Patra <atishp@atishpatra.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	kasan-dev@googlegroups.com, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	kvm-riscv@lists.infradead.org, linux-efi@vger.kernel.org,
	linux-mm@kvack.org
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Subject: [PATCH v2 1/4] riscv: Use WRITE_ONCE() when setting page table entries
Date: Wed, 13 Dec 2023 21:29:58 +0100	[thread overview]
Message-ID: <20231213203001.179237-2-alexghiti@rivosinc.com> (raw)
In-Reply-To: <20231213203001.179237-1-alexghiti@rivosinc.com>

To avoid any compiler "weirdness" when accessing page table entries which
are concurrently modified by the HW, let's use WRITE_ONCE() macro
(commit 20a004e7b017 ("arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing
page tables") gives a great explanation with more details).

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/include/asm/pgtable-64.h | 6 +++---
 arch/riscv/include/asm/pgtable.h    | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 9a2c780a11e9..5d8431a390dd 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -202,7 +202,7 @@ static inline int pud_user(pud_t pud)
 
 static inline void set_pud(pud_t *pudp, pud_t pud)
 {
-	*pudp = pud;
+	WRITE_ONCE(*pudp, pud);
 }
 
 static inline void pud_clear(pud_t *pudp)
@@ -278,7 +278,7 @@ static inline unsigned long _pmd_pfn(pmd_t pmd)
 static inline void set_p4d(p4d_t *p4dp, p4d_t p4d)
 {
 	if (pgtable_l4_enabled)
-		*p4dp = p4d;
+		WRITE_ONCE(*p4dp, p4d);
 	else
 		set_pud((pud_t *)p4dp, (pud_t){ p4d_val(p4d) });
 }
@@ -351,7 +351,7 @@ static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
 static inline void set_pgd(pgd_t *pgdp, pgd_t pgd)
 {
 	if (pgtable_l5_enabled)
-		*pgdp = pgd;
+		WRITE_ONCE(*pgdp, pgd);
 	else
 		set_p4d((p4d_t *)pgdp, (p4d_t){ pgd_val(pgd) });
 }
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 294044429e8e..c9f4b250b4ee 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -248,7 +248,7 @@ static inline int pmd_leaf(pmd_t pmd)
 
 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
-	*pmdp = pmd;
+	WRITE_ONCE(*pmdp, pmd);
 }
 
 static inline void pmd_clear(pmd_t *pmdp)
@@ -510,7 +510,7 @@ static inline int pte_same(pte_t pte_a, pte_t pte_b)
  */
 static inline void set_pte(pte_t *ptep, pte_t pteval)
 {
-	*ptep = pteval;
+	WRITE_ONCE(*ptep, pteval);
 }
 
 void flush_icache_pte(pte_t pte);
-- 
2.39.2


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  reply	other threads:[~2023-12-13 20:31 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-13 20:29 [PATCH v2 0/4] riscv: Use READ_ONCE()/WRITE_ONCE() for pte accesses Alexandre Ghiti
2023-12-13 20:29 ` Alexandre Ghiti
2023-12-13 20:29 ` Alexandre Ghiti [this message]
2023-12-13 20:29   ` [PATCH v2 1/4] riscv: Use WRITE_ONCE() when setting page table entries Alexandre Ghiti
2023-12-13 20:29 ` [PATCH v2 2/4] mm: Introduce pudp/p4dp/pgdp_get() functions Alexandre Ghiti
2023-12-13 20:29   ` Alexandre Ghiti
2023-12-13 20:30 ` [PATCH v2 3/4] riscv: mm: Only compile pgtable.c if MMU Alexandre Ghiti
2023-12-13 20:30   ` Alexandre Ghiti
2023-12-13 20:30 ` [PATCH v2 4/4] riscv: Use accessors to page table entries instead of direct dereference Alexandre Ghiti
2023-12-13 20:30   ` Alexandre Ghiti
2023-12-14  5:34   ` Anup Patel
2023-12-14  5:34     ` Anup Patel
2024-01-05 21:50 ` [PATCH v2 0/4] riscv: Use READ_ONCE()/WRITE_ONCE() for pte accesses patchwork-bot+linux-riscv
2024-01-05 21:50   ` patchwork-bot+linux-riscv

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