[PATCH v7 36/50] arm64: mm: Wire up TCR.DS bit to PTE shareability fields

From: Ard Biesheuvel <ardb+git@google.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Ryan Roberts <ryan.roberts@arm.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	 Kees Cook <keescook@chromium.org>
Subject: [PATCH v7 36/50] arm64: mm: Wire up TCR.DS bit to PTE shareability fields
Date: Tue, 23 Jan 2024 15:53:35 +0100	[thread overview]
Message-ID: <20240123145258.1462979-88-ardb+git@google.com> (raw)
In-Reply-To: <20240123145258.1462979-52-ardb+git@google.com>

From: Ard Biesheuvel <ardb@kernel.org>

When LPA2 is enabled, bits 8 and 9 of page and block descriptors become
part of the output address instead of carrying shareability attributes
for the region in question.

So avoid setting these bits if TCR.DS == 1, which means LPA2 is enabled.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/Kconfig                     |  4 ++++
 arch/arm64/include/asm/pgtable-hwdef.h |  1 +
 arch/arm64/include/asm/pgtable-prot.h  | 16 ++++++++++++++--
 arch/arm64/mm/mmap.c                   |  4 ++++
 arch/arm64/mm/proc.S                   |  2 ++
 5 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index aa7c1d435139..8c2c36fffcf5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1377,6 +1377,10 @@ config ARM64_PA_BITS
 	default 48 if ARM64_PA_BITS_48
 	default 52 if ARM64_PA_BITS_52
 
+config ARM64_LPA2
+	def_bool y
+	depends on ARM64_PA_BITS_52 && !ARM64_64K_PAGES
+
 choice
 	prompt "Endianness"
 	default CPU_LITTLE_ENDIAN
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index e4944d517c99..b770f98fc0b5 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -284,6 +284,7 @@
 #define TCR_E0PD1		(UL(1) << 56)
 #define TCR_TCMA0		(UL(1) << 57)
 #define TCR_TCMA1		(UL(1) << 58)
+#define TCR_DS			(UL(1) << 59)
 
 /*
  * TTBR.
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 63ced9ccec21..dd9ee67d1d87 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -30,8 +30,8 @@
 #define _PROT_DEFAULT		(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
 #define _PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
 
-#define PROT_DEFAULT		(_PROT_DEFAULT | PTE_MAYBE_NG)
-#define PROT_SECT_DEFAULT	(_PROT_SECT_DEFAULT | PMD_MAYBE_NG)
+#define PROT_DEFAULT		(PTE_TYPE_PAGE | PTE_MAYBE_NG | PTE_MAYBE_SHARED | PTE_AF)
+#define PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_MAYBE_NG | PMD_MAYBE_SHARED | PMD_SECT_AF)
 
 #define PROT_DEVICE_nGnRnE	(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRnE))
 #define PROT_DEVICE_nGnRE	(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_WRITE | PTE_ATTRINDX(MT_DEVICE_nGnRE))
@@ -67,7 +67,19 @@ extern bool arm64_use_ng_mappings;
 #define PTE_MAYBE_NG		(arm64_use_ng_mappings ? PTE_NG : 0)
 #define PMD_MAYBE_NG		(arm64_use_ng_mappings ? PMD_SECT_NG : 0)
 
+#ifndef CONFIG_ARM64_LPA2
 #define lpa2_is_enabled()	false
+#define PTE_MAYBE_SHARED	PTE_SHARED
+#define PMD_MAYBE_SHARED	PMD_SECT_S
+#else
+static inline bool __pure lpa2_is_enabled(void)
+{
+	return read_tcr() & TCR_DS;
+}
+
+#define PTE_MAYBE_SHARED	(lpa2_is_enabled() ? 0 : PTE_SHARED)
+#define PMD_MAYBE_SHARED	(lpa2_is_enabled() ? 0 : PMD_SECT_S)
+#endif
 
 /*
  * If we have userspace only BTI we don't want to mark kernel pages
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index 645fe60d000f..642bdf908b22 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -73,6 +73,10 @@ static int __init adjust_protection_map(void)
 		protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY;
 	}
 
+	if (lpa2_is_enabled())
+		for (int i = 0; i < ARRAY_SIZE(protection_map); i++)
+			pgprot_val(protection_map[i]) &= ~PTE_SHARED;
+
 	return 0;
 }
 arch_initcall(adjust_protection_map);
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 6e1b2bc41a9f..7c46f8cfd6ae 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -466,6 +466,7 @@ alternative_else_nop_endif
 	 */
 
 #define PTE_MAYBE_NG		0
+#define PTE_MAYBE_SHARED	0
 
 	mov_q	x0, PIE_E0
 	msr	REG_PIRE0_EL1, x0
@@ -473,6 +474,7 @@ alternative_else_nop_endif
 	msr	REG_PIR_EL1, x0
 
 #undef PTE_MAYBE_NG
+#undef PTE_MAYBE_SHARED
 
 	mov	x0, TCR2_EL1x_PIE
 	msr	REG_TCR2_EL1, x0
-- 
2.43.0.429.g432eaa2c6b-goog


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