From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id E39EB6B0293 for ; Wed, 11 Jul 2018 07:30:22 -0400 (EDT) Received: by mail-ed1-f70.google.com with SMTP id a22-v6so9880762eds.13 for ; Wed, 11 Jul 2018 04:30:22 -0700 (PDT) Received: from theia.8bytes.org (8bytes.org. [81.169.241.247]) by mx.google.com with ESMTPS id a90-v6si364106ede.124.2018.07.11.04.30.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Jul 2018 04:30:21 -0700 (PDT) From: Joerg Roedel Subject: [PATCH 35/39] x86/ldt: Split out sanity check in map_ldt_struct() Date: Wed, 11 Jul 2018 13:29:42 +0200 Message-Id: <1531308586-29340-36-git-send-email-joro@8bytes.org> In-Reply-To: <1531308586-29340-1-git-send-email-joro@8bytes.org> References: <1531308586-29340-1-git-send-email-joro@8bytes.org> Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , "David H . Gutteridge" , jroedel@suse.de, joro@8bytes.org From: Joerg Roedel This splits out the mapping sanity check and the actual mapping of the LDT to user-space from the map_ldt_struct() function in a way so that it is re-usable for PAE paging. Signed-off-by: Joerg Roedel --- arch/x86/kernel/ldt.c | 82 ++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 58 insertions(+), 24 deletions(-) diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index e921b3d..69af9a0 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -100,6 +100,49 @@ static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries) return new_ldt; } +#ifdef CONFIG_PAGE_TABLE_ISOLATION + +static void do_sanity_check(struct mm_struct *mm, + bool had_kernel_mapping, + bool had_user_mapping) +{ + if (mm->context.ldt) { + /* + * We already had an LDT. The top-level entry should already + * have been allocated and synchronized with the usermode + * tables. + */ + WARN_ON(!had_kernel_mapping); + if (static_cpu_has(X86_FEATURE_PTI)) + WARN_ON(!had_user_mapping); + } else { + /* + * This is the first time we're mapping an LDT for this process. + * Sync the pgd to the usermode tables. + */ + WARN_ON(had_kernel_mapping); + if (static_cpu_has(X86_FEATURE_PTI)) + WARN_ON(had_user_mapping); + } +} + +static void map_ldt_struct_to_user(struct mm_struct *mm) +{ + pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR); + + if (static_cpu_has(X86_FEATURE_PTI) && !mm->context.ldt) + set_pgd(kernel_to_user_pgdp(pgd), *pgd); +} + +static void sanity_check_ldt_mapping(struct mm_struct *mm) +{ + pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR); + bool had_kernel = (pgd->pgd != 0); + bool had_user = (kernel_to_user_pgdp(pgd)->pgd != 0); + + do_sanity_check(mm, had_kernel, had_user); +} + /* * If PTI is enabled, this maps the LDT into the kernelmode and * usermode tables for the given mm. @@ -115,9 +158,8 @@ static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries) static int map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot) { -#ifdef CONFIG_PAGE_TABLE_ISOLATION - bool is_vmalloc, had_top_level_entry; unsigned long va; + bool is_vmalloc; spinlock_t *ptl; pgd_t *pgd; int i; @@ -131,13 +173,15 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot) */ WARN_ON(ldt->slot != -1); + /* Check if the current mappings are sane */ + sanity_check_ldt_mapping(mm); + /* * Did we already have the top level entry allocated? We can't * use pgd_none() for this because it doens't do anything on * 4-level page table kernels. */ pgd = pgd_offset(mm, LDT_BASE_ADDR); - had_top_level_entry = (pgd->pgd != 0); is_vmalloc = is_vmalloc_addr(ldt->entries); @@ -172,35 +216,25 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot) pte_unmap_unlock(ptep, ptl); } - if (mm->context.ldt) { - /* - * We already had an LDT. The top-level entry should already - * have been allocated and synchronized with the usermode - * tables. - */ - WARN_ON(!had_top_level_entry); - if (static_cpu_has(X86_FEATURE_PTI)) - WARN_ON(!kernel_to_user_pgdp(pgd)->pgd); - } else { - /* - * This is the first time we're mapping an LDT for this process. - * Sync the pgd to the usermode tables. - */ - WARN_ON(had_top_level_entry); - if (static_cpu_has(X86_FEATURE_PTI)) { - WARN_ON(kernel_to_user_pgdp(pgd)->pgd); - set_pgd(kernel_to_user_pgdp(pgd), *pgd); - } - } + /* Propagate LDT mapping to the user page-table */ + map_ldt_struct_to_user(mm); va = (unsigned long)ldt_slot_va(slot); flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, 0); ldt->slot = slot; -#endif return 0; } +#else /* !CONFIG_PAGE_TABLE_ISOLATION */ + +static int +map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot) +{ + return 0; +} +#endif /* CONFIG_PAGE_TABLE_ISOLATION */ + static void free_ldt_pgtables(struct mm_struct *mm) { #ifdef CONFIG_PAGE_TABLE_ISOLATION -- 2.7.4