Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754985AbbLDBVr (ORCPT ); Thu, 3 Dec 2015 20:21:47 -0500 Received: from mga01.intel.com ([192.55.52.88]:64911 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754603AbbLDBOj (ORCPT ); Thu, 3 Dec 2015 20:14:39 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,378,1444719600"; d="scan'208";a="853564953" Subject: [PATCH 10/34] x86, pkeys: arch-specific protection bits To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, Dave Hansen , dave.hansen@linux.intel.com From: Dave Hansen Date: Thu, 03 Dec 2015 17:14:38 -0800 References: <20151204011424.8A36E365@viggo.jf.intel.com> In-Reply-To: <20151204011424.8A36E365@viggo.jf.intel.com> Message-Id: <20151204011438.E50D1498@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5714 Lines: 148 From: Dave Hansen Lots of things seem to do: vma->vm_page_prot = vm_get_page_prot(flags); and the ptes get created right from things we pull out of ->vm_page_prot. So it is very convenient if we can store the protection key in flags and vm_page_prot, just like the existing permission bits (_PAGE_RW/PRESENT). It greatly reduces the amount of plumbing and arch-specific hacking we have to do in generic code. This also takes the new PROT_PKEY{0,1,2,3} flags and turns *those* in to VM_ flags for vma->vm_flags. The protection key values are stored in 4 places: 1. "prot" argument to system calls 2. vma->vm_flags, filled from the mmap "prot" 3. vma->vm_page prot, filled from vma->vm_flags 4. the PTE itself. The pseudocode for these for steps are as follows: mmap(PROT_PKEY*) vma->vm_flags = ... | arch_calc_vm_prot_bits(mmap_prot); vma->vm_page_prot = ... | arch_vm_get_page_prot(vma->vm_flags); pte = pfn | vma->vm_page_prot Note that this provides a new definitions for x86: arch_vm_get_page_prot() Signed-off-by: Dave Hansen --- b/arch/x86/include/asm/mmu_context.h | 20 ++++++++++++++++++++ b/arch/x86/include/asm/pgtable_types.h | 12 ++++++++++-- b/arch/x86/include/uapi/asm/mman.h | 16 ++++++++++++++++ b/include/linux/mm.h | 6 ++++++ 4 files changed, 52 insertions(+), 2 deletions(-) diff -puN arch/x86/include/asm/mmu_context.h~pkeys-08-store-pkey-in-vma arch/x86/include/asm/mmu_context.h --- a/arch/x86/include/asm/mmu_context.h~pkeys-08-store-pkey-in-vma 2015-12-03 16:21:22.505529763 -0800 +++ b/arch/x86/include/asm/mmu_context.h 2015-12-03 16:21:22.514530171 -0800 @@ -243,4 +243,24 @@ static inline void arch_unmap(struct mm_ mpx_notify_unmap(mm, vma, start, end); } +static inline int vma_pkey(struct vm_area_struct *vma) +{ + u16 pkey = 0; +#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS + unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 | + VM_PKEY_BIT2 | VM_PKEY_BIT3; + /* + * ffs is one-based, not zero-based, so bias back down by 1. + */ + int vm_pkey_shift = __builtin_ffsl(vma_pkey_mask) - 1; + /* + * gcc generates better code if we do this rather than: + * pkey = (flags & mask) >> shift + */ + pkey = (vma->vm_flags >> vm_pkey_shift) & + (vma_pkey_mask >> vm_pkey_shift); +#endif + return pkey; +} + #endif /* _ASM_X86_MMU_CONTEXT_H */ diff -puN arch/x86/include/asm/pgtable_types.h~pkeys-08-store-pkey-in-vma arch/x86/include/asm/pgtable_types.h --- a/arch/x86/include/asm/pgtable_types.h~pkeys-08-store-pkey-in-vma 2015-12-03 16:21:22.507529853 -0800 +++ b/arch/x86/include/asm/pgtable_types.h 2015-12-03 16:21:22.514530171 -0800 @@ -111,7 +111,12 @@ #define _KERNPG_TABLE (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | \ _PAGE_DIRTY) -/* Set of bits not changed in pte_modify */ +/* + * Set of bits not changed in pte_modify. The pte's + * protection key is treated like _PAGE_RW, for + * instance, and is *not* included in this mask since + * pte_modify() does modify it. + */ #define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \ _PAGE_SOFT_DIRTY) @@ -227,7 +232,10 @@ enum page_cache_mode { /* Extracts the PFN from a (pte|pmd|pud|pgd)val_t of a 4KB page */ #define PTE_PFN_MASK ((pteval_t)PHYSICAL_PAGE_MASK) -/* Extracts the flags from a (pte|pmd|pud|pgd)val_t of a 4KB page */ +/* + * Extracts the flags from a (pte|pmd|pud|pgd)val_t + * This includes the protection key value. + */ #define PTE_FLAGS_MASK (~PTE_PFN_MASK) typedef struct pgprot { pgprotval_t pgprot; } pgprot_t; diff -puN arch/x86/include/uapi/asm/mman.h~pkeys-08-store-pkey-in-vma arch/x86/include/uapi/asm/mman.h --- a/arch/x86/include/uapi/asm/mman.h~pkeys-08-store-pkey-in-vma 2015-12-03 16:21:22.509529944 -0800 +++ b/arch/x86/include/uapi/asm/mman.h 2015-12-03 16:21:22.514530171 -0800 @@ -6,6 +6,22 @@ #define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT) #define MAP_HUGE_1GB (30 << MAP_HUGE_SHIFT) +#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS +/* + * Take the 4 protection key bits out of the vma->vm_flags + * value and turn them in to the bits that we can put in + * to a pte. + * + * Only override these if Protection Keys are available + * (which is only on 64-bit). + */ +#define arch_vm_get_page_prot(vm_flags) __pgprot( \ + ((vm_flags) & VM_PKEY_BIT0 ? _PAGE_PKEY_BIT0 : 0) | \ + ((vm_flags) & VM_PKEY_BIT1 ? _PAGE_PKEY_BIT1 : 0) | \ + ((vm_flags) & VM_PKEY_BIT2 ? _PAGE_PKEY_BIT2 : 0) | \ + ((vm_flags) & VM_PKEY_BIT3 ? _PAGE_PKEY_BIT3 : 0)) +#endif + #include #endif /* _ASM_X86_MMAN_H */ diff -puN include/linux/mm.h~pkeys-08-store-pkey-in-vma include/linux/mm.h --- a/include/linux/mm.h~pkeys-08-store-pkey-in-vma 2015-12-03 16:21:22.510529990 -0800 +++ b/include/linux/mm.h 2015-12-03 16:21:22.515530216 -0800 @@ -167,6 +167,12 @@ extern unsigned int kobjsize(const void #if defined(CONFIG_X86) # define VM_PAT VM_ARCH_1 /* PAT reserves whole VMA at once (x86) */ +#if defined (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) +# define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 4-bit value */ +# define VM_PKEY_BIT1 VM_HIGH_ARCH_1 +# define VM_PKEY_BIT2 VM_HIGH_ARCH_2 +# define VM_PKEY_BIT3 VM_HIGH_ARCH_3 +#endif #elif defined(CONFIG_PPC) # define VM_SAO VM_ARCH_1 /* Strong Access Ordering (powerpc) */ #elif defined(CONFIG_PARISC) _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/