From patchwork Sun Jun 26 21:55:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Lutomirski X-Patchwork-Id: 9199699 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 277B160752 for ; Sun, 26 Jun 2016 21:59:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 18B7428521 for ; Sun, 26 Jun 2016 21:59:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0D1E62855A; Sun, 26 Jun 2016 21:59:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id D521528521 for ; Sun, 26 Jun 2016 21:59:31 +0000 (UTC) Received: (qmail 1619 invoked by uid 550); 26 Jun 2016 21:56:44 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 32753 invoked from network); 26 Jun 2016 21:56:36 -0000 From: Andy Lutomirski To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Borislav Petkov , Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf , Jann Horn , Heiko Carstens , Andy Lutomirski Date: Sun, 26 Jun 2016 14:55:49 -0700 Message-Id: X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: X-Virus-Scanned: ClamAV using ClamSMTP Subject: [kernel-hardening] [PATCH v4 27/29] x86: Move thread_info into task_struct X-Virus-Scanned: ClamAV using ClamSMTP Now that most of the thread_info users have been cleaned up, this is straightforward. Most of this code was written by Linus. Signed-off-by: Andy Lutomirski --- arch/x86/Kconfig | 1 + arch/x86/entry/entry_64.S | 9 +++++--- arch/x86/include/asm/switch_to.h | 6 ++--- arch/x86/include/asm/thread_info.h | 46 -------------------------------------- arch/x86/kernel/asm-offsets.c | 4 +--- arch/x86/kernel/irq_64.c | 3 +-- arch/x86/kernel/process.c | 6 ++--- 7 files changed, 13 insertions(+), 62 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index afdcf96ef109..b3002c8efde2 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -155,6 +155,7 @@ config X86 select SPARSE_IRQ select SRCU select SYSCTL_EXCEPTION_TRACE + select THREAD_INFO_IN_TASK select USER_STACKTRACE_SUPPORT select VIRT_TO_BUS select X86_DEV_DMA_OPS if X86_64 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index b846875aeea6..efeb1c9f64f4 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -179,7 +179,8 @@ GLOBAL(entry_SYSCALL_64_after_swapgs) * If we need to do entry work or if we guess we'll need to do * exit work, go straight to the slow path. */ - testl $_TIF_WORK_SYSCALL_ENTRY|_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) + movq %gs:current_task, %r11 + testl $_TIF_WORK_SYSCALL_ENTRY|_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) jnz entry_SYSCALL64_slow_path entry_SYSCALL_64_fastpath: @@ -217,7 +218,8 @@ entry_SYSCALL_64_fastpath: */ DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF - testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) + movq %gs:current_task, %r11 + testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) jnz 1f LOCKDEP_SYS_EXIT @@ -368,9 +370,10 @@ END(ptregs_\func) * A newly forked process directly context switches into this address. * * rdi: prev task we switched from + * rsi: task we're switching to */ ENTRY(ret_from_fork) - LOCK ; btr $TIF_FORK, TI_flags(%r8) + LOCK ; btr $TIF_FORK, TASK_TI_flags(%rsi) call schedule_tail /* rdi: 'prev' task parameter */ diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h index 14e4b20f0aaf..5194f4a680ab 100644 --- a/arch/x86/include/asm/switch_to.h +++ b/arch/x86/include/asm/switch_to.h @@ -136,18 +136,16 @@ do { \ "call __switch_to\n\t" \ "movq "__percpu_arg([current_task])",%%rsi\n\t" \ __switch_canary \ - "movq %P[thread_info](%%rsi),%%r8\n\t" \ "movq %%rax,%%rdi\n\t" \ - "testl %[_tif_fork],%P[ti_flags](%%r8)\n\t" \ + "testl %[_tif_fork],%P[ti_flags](%%rsi)\n\t" \ "jnz ret_from_fork\n\t" \ RESTORE_CONTEXT \ : "=a" (last) \ __switch_canary_oparam \ : [next] "S" (next), [prev] "D" (prev), \ [threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \ - [ti_flags] "i" (offsetof(struct thread_info, flags)), \ + [ti_flags] "i" (offsetof(struct task_struct, thread_info.flags)), \ [_tif_fork] "i" (_TIF_FORK), \ - [thread_info] "i" (offsetof(struct task_struct, stack)), \ [current_task] "m" (current_task) \ __switch_canary_iparam \ : "memory", "cc" __EXTRA_CLOBBER) diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 7b42c1e462ac..0afc37654ad1 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -52,20 +52,6 @@ struct task_struct; #include #include -struct thread_info { - struct task_struct *task; /* main task structure */ - __u32 flags; /* low level flags */ - __u32 cpu; /* current CPU */ -}; - -#define INIT_THREAD_INFO(tsk) \ -{ \ - .task = &tsk, \ - .flags = 0, \ - .cpu = 0, \ -} - -#define init_thread_info (init_thread_union.thread_info) #define init_stack (init_thread_union.stack) #else /* !__ASSEMBLY__ */ @@ -159,11 +145,6 @@ struct thread_info { */ #ifndef __ASSEMBLY__ -static inline struct thread_info *current_thread_info(void) -{ - return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); -} - static inline unsigned long current_stack_pointer(void) { unsigned long sp; @@ -181,33 +162,6 @@ static inline unsigned long current_stack_pointer(void) # define cpu_current_top_of_stack (cpu_tss + TSS_sp0) #endif -/* - * ASM operand which evaluates to a 'thread_info' address of - * the current task, if it is known that "reg" is exactly "off" - * bytes below the top of the stack currently. - * - * ( The kernel stack's size is known at build time, it is usually - * 2 or 4 pages, and the bottom of the kernel stack contains - * the thread_info structure. So to access the thread_info very - * quickly from assembly code we can calculate down from the - * top of the kernel stack to the bottom, using constant, - * build-time calculations only. ) - * - * For example, to fetch the current thread_info->flags value into %eax - * on x86-64 defconfig kernels, in syscall entry code where RSP is - * currently at exactly SIZEOF_PTREGS bytes away from the top of the - * stack: - * - * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax - * - * will translate to: - * - * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax - * - * which is below the current RSP by almost 16K. - */ -#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg) - #endif #ifndef __ASSEMBLY__ diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index a91a6ead24a2..e900f5e13f22 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -29,9 +29,7 @@ void common(void) { BLANK(); - OFFSET(TI_flags, thread_info, flags); - - BLANK(); + OFFSET(TASK_TI_flags, task_struct, thread_info.flags); OFFSET(TASK_addr_limit, task_struct, thread.addr_limit); BLANK(); diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index 206d0b90a3ab..38f9f5678dc8 100644 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -41,8 +41,7 @@ static inline void stack_overflow_check(struct pt_regs *regs) if (user_mode(regs)) return; - if (regs->sp >= curbase + sizeof(struct thread_info) + - sizeof(struct pt_regs) + STACK_TOP_MARGIN && + if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_TOP_MARGIN && regs->sp <= curbase + THREAD_SIZE) return; diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 96becbbb52e0..8f60f810a9e7 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -536,9 +536,7 @@ unsigned long get_wchan(struct task_struct *p) * PADDING * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING * stack - * ----------- bottom = start + sizeof(thread_info) - * thread_info - * ----------- start + * ----------- bottom = start * * The tasks stack pointer points at the location where the * framepointer is stored. The data on the stack is: @@ -549,7 +547,7 @@ unsigned long get_wchan(struct task_struct *p) */ top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; top -= 2 * sizeof(unsigned long); - bottom = start + sizeof(struct thread_info); + bottom = start; sp = READ_ONCE(p->thread.sp); if (sp < bottom || sp > top)