From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:43186 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729879AbfLKSlD (ORCPT ); Wed, 11 Dec 2019 13:41:03 -0500 From: Catalin Marinas Subject: [PATCH 15/22] arm64: mte: Add PROT_MTE support to mmap() and mprotect() Date: Wed, 11 Dec 2019 18:40:20 +0000 Message-ID: <20191211184027.20130-16-catalin.marinas@arm.com> In-Reply-To: <20191211184027.20130-1-catalin.marinas@arm.com> References: <20191211184027.20130-1-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-arm-kernel@lists.infradead.org Cc: Will Deacon , Marc Zyngier , Vincenzo Frascino , Szabolcs Nagy , Richard Earnshaw , Kevin Brodsky , Andrey Konovalov , linux-mm@kvack.org, linux-arch@vger.kernel.org Message-ID: <20191211184020.n6UVFg4sGqmDtZYwPziRACh2W1paVBg-kplYnaEVMRY@z> To enable tagging on a memory range, the user must explicitly opt in via a new PROT_MTE flag passed to mmap() or mprotect(). Since this is a new memory type in the AttrIndx field of a pte, simplify the or'ing of these bits over the protection_map[] attributes by making MT_NORMAL index 0. There are two conditions for arch_vm_get_page_prot() to return the MT_NORMAL_TAGGED memory type: (1) the user requested it via PROT_MTE, registered as VM_MTE in the vm_flags, and (2) the vma supports MTE, decided during the mmap() call (only) and registered as VM_MTE_ALLOWED. arch_calc_vm_prot_bits() is responsible for registering the user request as VM_MTE. The newly introduced arch_calc_vm_flag_bits() sets VM_MTE_ALLOWED if the mapping is MAP_ANONYMOUS. An MTE-capable filesystem (RAM-based) may be able to set VM_MTE_ALLOWED during its mmap() file ops call. In addition, update VM_DATA_DEFAULT_FLAGS to allow mprotect(PROT_MTE) on stack or brk area. The Linux mmap() syscall currently ignores unknown PROT_* flags. In the presence of MTE, an mmap(PROT_MTE) on a file which does not support MTE will not report an error and the memory will not be mapped as Normal Tagged. For consistency, mprotect(PROT_MTE) will not report an error either if the memory range does not support MTE. Two subsequent patches in the series will propose tightening of this behaviour. Co-developed-by: Vincenzo Frascino Signed-off-by: Vincenzo Frascino Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/memory.h | 18 +++++---- arch/arm64/include/asm/mman.h | 64 ++++++++++++++++++++++++++++++ arch/arm64/include/asm/page.h | 4 +- arch/arm64/include/asm/pgtable.h | 7 +++- arch/arm64/include/uapi/asm/mman.h | 14 +++++++ fs/proc/task_mmu.c | 3 ++ include/linux/mm.h | 8 ++++ 7 files changed, 109 insertions(+), 9 deletions(-) create mode 100644 arch/arm64/include/asm/mman.h create mode 100644 arch/arm64/include/uapi/asm/mman.h diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 55994ab362ae..f0e535895a78 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -138,14 +138,18 @@ /* * Memory types available. + * + * IMPORTANT: MT_NORMAL must be index 0 since vm_get_page_prot() may 'or' in + * the MT_NORMAL_TAGGED memory type for PROT_MTE mappings. Note + * that protection_map[] only contains MT_NORMAL attributes. */ -#define MT_DEVICE_nGnRnE 0 -#define MT_DEVICE_nGnRE 1 -#define MT_DEVICE_GRE 2 -#define MT_NORMAL_NC 3 -#define MT_NORMAL 4 -#define MT_NORMAL_WT 5 -#define MT_NORMAL_TAGGED 6 +#define MT_NORMAL 0 +#define MT_NORMAL_TAGGED 1 +#define MT_NORMAL_NC 2 +#define MT_NORMAL_WT 3 +#define MT_DEVICE_nGnRnE 4 +#define MT_DEVICE_nGnRE 5 +#define MT_DEVICE_GRE 6 /* * Memory types for Stage-2 translation diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h new file mode 100644 index 000000000000..c77a23869223 --- /dev/null +++ b/arch/arm64/include/asm/mman.h @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_MMAN_H__ +#define __ASM_MMAN_H__ + +#include + +/* + * There are two conditions required for returning a Normal Tagged memory type + * in arch_vm_get_page_prot(): (1) the user requested it via PROT_MTE passed + * to mmap() or mprotect() and (2) the corresponding vma supports MTE. We + * register (1) as VM_MTE in the vma->vm_flags and (2) as VM_MTE_ALLOWED. Note + * that the latter can only be set during the mmap() call since mprotect() + * does not accept MAP_* flags. + */ +static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, + unsigned long pkey) +{ + if (!system_supports_mte()) + return 0; + + if (prot & PROT_MTE) + return VM_MTE; + + return 0; +} +#define arch_calc_vm_prot_bits arch_calc_vm_prot_bits + +static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags) +{ + if (!system_supports_mte()) + return 0; + + /* + * Only allow MTE on anonymous mappings as these are guaranteed to be + * backed by tags-capable memory. The vm_flags may be overridden by a + * filesystem supporting MTE (RAM-based). + */ + if (flags & MAP_ANONYMOUS) + return VM_MTE_ALLOWED; + + return 0; +} +#define arch_calc_vm_flag_bits arch_calc_vm_flag_bits + +static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags) +{ + return (vm_flags & VM_MTE) && (vm_flags & VM_MTE_ALLOWED) ? + __pgprot(PTE_ATTRINDX(MT_NORMAL_TAGGED)) : + __pgprot(0); +} +#define arch_vm_get_page_prot arch_vm_get_page_prot + +static inline bool arch_validate_prot(unsigned long prot, unsigned long addr) +{ + unsigned long supported = PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM; + + if (system_supports_mte()) + supported |= PROT_MTE; + + return (prot & ~supported) == 0; +} +#define arch_validate_prot arch_validate_prot + +#endif /* !__ASM_MMAN_H__ */ diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index d39ddb258a04..10d71f927b70 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -32,9 +32,11 @@ extern int pfn_valid(unsigned long); #endif /* !__ASSEMBLY__ */ +/* Used for stack and brk memory ranges */ #define VM_DATA_DEFAULT_FLAGS \ (((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0) | \ - VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC) + VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | \ + VM_MTE_ALLOWED) #include diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 5d15b4735a0e..e5e2cb6f2f3c 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -661,8 +661,13 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd) static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { + /* + * Normal and Normal-Tagged are two different memory types and indices + * in MAIR_EL1. The mask below has to include PTE_ATTRINDX_MASK. + */ const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY | - PTE_PROT_NONE | PTE_VALID | PTE_WRITE; + PTE_PROT_NONE | PTE_VALID | PTE_WRITE | + PTE_ATTRINDX_MASK; /* preserve the hardware dirty information */ if (pte_hw_dirty(pte)) pte = pte_mkdirty(pte); diff --git a/arch/arm64/include/uapi/asm/mman.h b/arch/arm64/include/uapi/asm/mman.h new file mode 100644 index 000000000000..d7677ee84878 --- /dev/null +++ b/arch/arm64/include/uapi/asm/mman.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI__ASM_MMAN_H +#define _UAPI__ASM_MMAN_H + +#include + +/* + * The generic mman.h file reserves 0x10 and 0x20 for arch-specific PROT_* + * flags. + */ +/* 0x10 reserved for PROT_BTI */ +#define PROT_MTE 0x20 /* Normal Tagged mapping */ + +#endif /* !_UAPI__ASM_MMAN_H */ diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 9442631fd4af..34bc9e0b4896 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -677,6 +677,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) [ilog2(VM_MERGEABLE)] = "mg", [ilog2(VM_UFFD_MISSING)]= "um", [ilog2(VM_UFFD_WP)] = "uw", +#ifdef CONFIG_ARM64_MTE + [ilog2(VM_MTE)] = "mt", +#endif #ifdef CONFIG_ARCH_HAS_PKEYS /* These come out via ProtectionKey: */ [ilog2(VM_PKEY_BIT0)] = "", diff --git a/include/linux/mm.h b/include/linux/mm.h index c97ea3b694e6..cf59b4558bbe 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -340,6 +340,14 @@ extern unsigned int kobjsize(const void *objp); # define VM_MPX VM_NONE #endif +#if defined(CONFIG_ARM64_MTE) +# define VM_MTE VM_HIGH_ARCH_0 /* Use Tagged memory for access control */ +# define VM_MTE_ALLOWED VM_HIGH_ARCH_1 /* Tagged memory permitted */ +#else +# define VM_MTE VM_NONE +# define VM_MTE_ALLOWED VM_NONE +#endif + #ifndef VM_GROWSUP # define VM_GROWSUP VM_NONE #endif