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2018-09-02x86/pti: Fix section mismatch warning/errorRandy Dunlap
Fix the section mismatch warning in arch/x86/mm/pti.c: WARNING: vmlinux.o(.text+0x6972a): Section mismatch in reference from the function pti_clone_pgtable() to the function .init.text:pti_user_pagetable_walk_pte() The function pti_clone_pgtable() references the function __init pti_user_pagetable_walk_pte(). This is often because pti_clone_pgtable lacks a __init annotation or the annotation of pti_user_pagetable_walk_pte is wrong. FATAL: modpost: Section mismatches detected. Fixes: 85900ea51577 ("x86/pti: Map the vsyscall page if needed") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/43a6d6a3-d69d-5eda-da09-0b1c88215a2a@infradead.org
2018-08-14Merge branch 'l1tf-final' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Merge L1 Terminal Fault fixes from Thomas Gleixner: "L1TF, aka L1 Terminal Fault, is yet another speculative hardware engineering trainwreck. It's a hardware vulnerability which allows unprivileged speculative access to data which is available in the Level 1 Data Cache when the page table entry controlling the virtual address, which is used for the access, has the Present bit cleared or other reserved bits set. If an instruction accesses a virtual address for which the relevant page table entry (PTE) has the Present bit cleared or other reserved bits set, then speculative execution ignores the invalid PTE and loads the referenced data if it is present in the Level 1 Data Cache, as if the page referenced by the address bits in the PTE was still present and accessible. While this is a purely speculative mechanism and the instruction will raise a page fault when it is retired eventually, the pure act of loading the data and making it available to other speculative instructions opens up the opportunity for side channel attacks to unprivileged malicious code, similar to the Meltdown attack. While Meltdown breaks the user space to kernel space protection, L1TF allows to attack any physical memory address in the system and the attack works across all protection domains. It allows an attack of SGX and also works from inside virtual machines because the speculation bypasses the extended page table (EPT) protection mechanism. The assoicated CVEs are: CVE-2018-3615, CVE-2018-3620, CVE-2018-3646 The mitigations provided by this pull request include: - Host side protection by inverting the upper address bits of a non present page table entry so the entry points to uncacheable memory. - Hypervisor protection by flushing L1 Data Cache on VMENTER. - SMT (HyperThreading) control knobs, which allow to 'turn off' SMT by offlining the sibling CPU threads. The knobs are available on the kernel command line and at runtime via sysfs - Control knobs for the hypervisor mitigation, related to L1D flush and SMT control. The knobs are available on the kernel command line and at runtime via sysfs - Extensive documentation about L1TF including various degrees of mitigations. Thanks to all people who have contributed to this in various ways - patches, review, testing, backporting - and the fruitful, sometimes heated, but at the end constructive discussions. There is work in progress to provide other forms of mitigations, which might be less horrible performance wise for a particular kind of workloads, but this is not yet ready for consumption due to their complexity and limitations" * 'l1tf-final' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits) x86/microcode: Allow late microcode loading with SMT disabled tools headers: Synchronise x86 cpufeatures.h for L1TF additions x86/mm/kmmio: Make the tracer robust against L1TF x86/mm/pat: Make set_memory_np() L1TF safe x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert x86/speculation/l1tf: Invert all not present mappings cpu/hotplug: Fix SMT supported evaluation KVM: VMX: Tell the nested hypervisor to skip L1D flush on vmentry x86/speculation: Use ARCH_CAPABILITIES to skip L1D flush on vmentry x86/speculation: Simplify sysfs report of VMX L1TF vulnerability Documentation/l1tf: Remove Yonah processors from not vulnerable list x86/KVM/VMX: Don't set l1tf_flush_l1d from vmx_handle_external_intr() x86/irq: Let interrupt handlers set kvm_cpu_l1tf_flush_l1d x86: Don't include linux/irq.h from asm/hardirq.h x86/KVM/VMX: Introduce per-host-cpu analogue of l1tf_flush_l1d x86/irq: Demote irq_cpustat_t::__softirq_pending to u16 x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush() x86/KVM/VMX: Replace 'vmx_l1d_flush_always' with 'vmx_l1d_flush_cond' x86/KVM/VMX: Don't set l1tf_flush_l1d to true from vmx_l1d_flush() cpu/hotplug: detect SMT disabled by BIOS ...
2018-08-10x86/mm/pti: Move user W+X check into pti_finalize()Joerg Roedel
The user page-table gets the updated kernel mappings in pti_finalize(), which runs after the RO+X permissions got applied to the kernel page-table in mark_readonly(). But with CONFIG_DEBUG_WX enabled, the user page-table is already checked in mark_readonly() for insecure mappings. This causes false-positive warnings, because the user page-table did not get the updated mappings yet. Move the W+X check for the user page-table into pti_finalize() after it updated all required mappings. [ tglx: Folded !NX supported fix ] Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1533727000-9172-1-git-send-email-joro@8bytes.org
2018-08-07x86/mm/pti: Clone kernel-image on PTE level for 32 bitJoerg Roedel
On 32 bit the kernel sections are not huge-page aligned. When we clone them on PMD-level we unevitably map some areas that are normal kernel memory and may contain secrets to user-space. To prevent that we need to clone the kernel-image on PTE-level for 32 bit. Also make the page-table cloning code more general so that it can handle PMD and PTE level cloning. This can be generalized further in the future to also handle clones on the P4D-level. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1533637471-30953-4-git-send-email-joro@8bytes.org
2018-08-07x86/mm/pti: Don't clear permissions in pti_clone_pmd()Joerg Roedel
The function sets the global-bit on cloned PMD entries, which only makes sense when the permissions are identical between the user and the kernel page-table. Further, only write-permissions are cleared for entry-text and kernel-text sections, which are not writeable at the end of the boot process. The reason why this RW clearing exists is that in the early PTI implementations the cloned kernel areas were set up during early boot before the kernel text is set to read only and not touched afterwards. This is not longer true. The cloned areas are still set up early to get the entry code working for interrupts and other things, but after the kernel text has been set RO the clone is repeated which copies the RO PMD/PTEs over to the user visible clone. That means the initial clearing of the writable bit can be avoided. [ tglx: Amended changelog ] Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Dave Hansen <dave.hansen@intel.com> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1533637471-30953-3-git-send-email-joro@8bytes.org
2018-08-07x86/mm/pti: Fix 32 bit PCID checkJoerg Roedel
The check uses the wrong operator and causes false positive warnings in the kernel log on some systems. Fixes: 5e8105950a8b3 ('x86/mm/pti: Add Warning when booting on a PCID capable CPU') Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1533637471-30953-2-git-send-email-joro@8bytes.org
2018-08-06Merge branch 'x86/pti-urgent' into x86/ptiThomas Gleixner
Integrate the PTI Global bit fixes which conflict with the 32bit PTI support. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-08-05x86/mm/pti: Clear Global bit more aggressivelyDave Hansen
The kernel image starts out with the Global bit set across the entire kernel image. The bit is cleared with set_memory_nonglobal() in the configurations with PCIDs where the performance benefits of the Global bit are not needed. However, this is fragile. It means that we are stuck opting *out* of the less-secure (Global bit set) configuration, which seems backwards. Let's start more secure (Global bit clear) and then let things opt back in if they want performance, or are truly mapping common data between kernel and userspace. This fixes a bug. Before this patch, there are areas that are unmapped from the user page tables (like like everything above 0xffffffff82600000 in the example below). These have the hallmark of being a wrong Global area: they are not identical in the 'current_kernel' and 'current_user' page table dumps. They are also read-write, which means they're much more likely to contain secrets. Before this patch: current_kernel:---[ High Kernel Mapping ]--- current_kernel-0xffffffff80000000-0xffffffff81000000 16M pmd current_kernel-0xffffffff81000000-0xffffffff81e00000 14M ro PSE GLB x pmd current_kernel-0xffffffff81e00000-0xffffffff81e11000 68K ro GLB x pte current_kernel-0xffffffff81e11000-0xffffffff82000000 1980K RW GLB NX pte current_kernel-0xffffffff82000000-0xffffffff82600000 6M ro PSE GLB NX pmd current_kernel-0xffffffff82600000-0xffffffff82c00000 6M RW PSE GLB NX pmd current_kernel-0xffffffff82c00000-0xffffffff82e00000 2M RW GLB NX pte current_kernel-0xffffffff82e00000-0xffffffff83200000 4M RW PSE GLB NX pmd current_kernel-0xffffffff83200000-0xffffffffa0000000 462M pmd current_user:---[ High Kernel Mapping ]--- current_user-0xffffffff80000000-0xffffffff81000000 16M pmd current_user-0xffffffff81000000-0xffffffff81e00000 14M ro PSE GLB x pmd current_user-0xffffffff81e00000-0xffffffff81e11000 68K ro GLB x pte current_user-0xffffffff81e11000-0xffffffff82000000 1980K RW GLB NX pte current_user-0xffffffff82000000-0xffffffff82600000 6M ro PSE GLB NX pmd current_user-0xffffffff82600000-0xffffffffa0000000 474M pmd After this patch: current_kernel:---[ High Kernel Mapping ]--- current_kernel-0xffffffff80000000-0xffffffff81000000 16M pmd current_kernel-0xffffffff81000000-0xffffffff81e00000 14M ro PSE GLB x pmd current_kernel-0xffffffff81e00000-0xffffffff81e11000 68K ro GLB x pte current_kernel-0xffffffff81e11000-0xffffffff82000000 1980K RW NX pte current_kernel-0xffffffff82000000-0xffffffff82600000 6M ro PSE GLB NX pmd current_kernel-0xffffffff82600000-0xffffffff82c00000 6M RW PSE NX pmd current_kernel-0xffffffff82c00000-0xffffffff82e00000 2M RW NX pte current_kernel-0xffffffff82e00000-0xffffffff83200000 4M RW PSE NX pmd current_kernel-0xffffffff83200000-0xffffffffa0000000 462M pmd current_user:---[ High Kernel Mapping ]--- current_user-0xffffffff80000000-0xffffffff81000000 16M pmd current_user-0xffffffff81000000-0xffffffff81e00000 14M ro PSE GLB x pmd current_user-0xffffffff81e00000-0xffffffff81e11000 68K ro GLB x pte current_user-0xffffffff81e11000-0xffffffff82000000 1980K RW NX pte current_user-0xffffffff82000000-0xffffffff82600000 6M ro PSE GLB NX pmd current_user-0xffffffff82600000-0xffffffffa0000000 474M pmd Fixes: 0f561fce4d69 ("x86/pti: Enable global pages for shared areas") Reported-by: Hugh Dickins <hughd@google.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: keescook@google.com Cc: aarcange@redhat.com Cc: jgross@suse.com Cc: jpoimboe@redhat.com Cc: gregkh@linuxfoundation.org Cc: peterz@infradead.org Cc: torvalds@linux-foundation.org Cc: bp@alien8.de Cc: luto@kernel.org Cc: ak@linux.intel.com Cc: Kees Cook <keescook@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Link: https://lkml.kernel.org/r/20180802225825.A100C071@viggo.jf.intel.com
2018-08-05x86: Don't include linux/irq.h from asm/hardirq.hNicolai Stange
The next patch in this series will have to make the definition of irq_cpustat_t available to entering_irq(). Inclusion of asm/hardirq.h into asm/apic.h would cause circular header dependencies like asm/smp.h asm/apic.h asm/hardirq.h linux/irq.h linux/topology.h linux/smp.h asm/smp.h or linux/gfp.h linux/mmzone.h asm/mmzone.h asm/mmzone_64.h asm/smp.h asm/apic.h asm/hardirq.h linux/irq.h linux/irqdesc.h linux/kobject.h linux/sysfs.h linux/kernfs.h linux/idr.h linux/gfp.h and others. This causes compilation errors because of the header guards becoming effective in the second inclusion: symbols/macros that had been defined before wouldn't be available to intermediate headers in the #include chain anymore. A possible workaround would be to move the definition of irq_cpustat_t into its own header and include that from both, asm/hardirq.h and asm/apic.h. However, this wouldn't solve the real problem, namely asm/harirq.h unnecessarily pulling in all the linux/irq.h cruft: nothing in asm/hardirq.h itself requires it. Also, note that there are some other archs, like e.g. arm64, which don't have that #include in their asm/hardirq.h. Remove the linux/irq.h #include from x86' asm/hardirq.h. Fix resulting compilation errors by adding appropriate #includes to *.c files as needed. Note that some of these *.c files could be cleaned up a bit wrt. to their set of #includes, but that should better be done from separate patches, if at all. Signed-off-by: Nicolai Stange <nstange@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-07-20x86/pti: Check the return value of pti_user_pagetable_walk_pmd()Jiang Biao
pti_user_pagetable_walk_pmd() can return NULL, so the return value should be checked to prevent a NULL pointer dereference. Add the check and a warning when the PMD allocation fails. Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: dave.hansen@linux.intel.com Cc: luto@kernel.org Cc: hpa@zytor.com Cc: albcamus@gmail.com Cc: zhong.weidong@zte.com.cn Link: https://lkml.kernel.org/r/1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn
2018-07-20x86/pti: Check the return value of pti_user_pagetable_walk_p4d()Jiang Biao
pti_user_pagetable_walk_p4d() can return NULL, so the return value should be checked to prevent a NULL pointer dereference. Add the check and a warning when the P4D allocation fails. Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: dave.hansen@linux.intel.com Cc: luto@kernel.org Cc: hpa@zytor.com Cc: albcamus@gmail.com Cc: zhong.weidong@zte.com.cn Link: https://lkml.kernel.org/r/1532045192-49622-1-git-send-email-jiang.biao2@zte.com.cn
2018-07-20x86/mm/pti: Add Warning when booting on a PCID capable CPUJoerg Roedel
Warn the user in case the performance can be significantly improved by switching to a 64-bit kernel. Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-39-git-send-email-joro@8bytes.org
2018-07-20x86/mm/pti: Clone entry-text again in pti_finalize()Joerg Roedel
The mapping for entry-text might have changed in the kernel after it was cloned to the user page-table. Clone again to update the user page-table to bring the mapping in sync with the kernel again. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-31-git-send-email-joro@8bytes.org
2018-07-20x86/mm/pti: Introduce pti_finalize()Joerg Roedel
Introduce a new function to finalize the kernel mappings for the userspace page-table after all ro/nx protections have been applied to the kernel mappings. Also move the call to pti_clone_kernel_text() to that function so that it will run on 32 bit kernels too. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-30-git-send-email-joro@8bytes.org
2018-07-20x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text()Joerg Roedel
Mapping the kernel text area to user-space makes only sense if it has the same permissions as in the kernel page-table. If permissions are different this will cause a TLB reload when using the kernel page-table, which is as good as not mapping it at all. On 64-bit kernels this patch makes no difference, as the whole range cloned by pti_clone_kernel_text() is mapped RO anyway. On 32 bit there are writeable mappings in the range, so just keep the permissions as they are. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-29-git-send-email-joro@8bytes.org
2018-07-20x86/mm/pti: Make pti_clone_kernel_text() compile on 32 bitJoerg Roedel
The pti_clone_kernel_text() function references __end_rodata_hpage_align, which is only present on x86-64. This makes sense as the end of the rodata section is not huge-page aligned on 32 bit. Nevertheless a symbol is required for the function that points at the right address for both 32 and 64 bit. Introduce __end_rodata_aligned for that purpose and use it in pti_clone_kernel_text(). Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-28-git-send-email-joro@8bytes.org
2018-07-20x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level on x86_32Joerg Roedel
Cloning on the P4D level would clone the complete kernel address space into the user-space page-tables for PAE kernels. Cloning on PMD level is fine for PAE and legacy paging. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-27-git-send-email-joro@8bytes.org
2018-07-20x86/mm/pti: Add an overflow check to pti_clone_pmds()Joerg Roedel
The addr counter will overflow if the last PMD of the address space is cloned, resulting in an endless loop. Check for that and bail out of the loop when it happens. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-25-git-send-email-joro@8bytes.org
2018-07-20x86/pgtable: Rename pti_set_user_pgd() to pti_set_user_pgtbl()Joerg Roedel
The way page-table folding is implemented on 32 bit, these functions are not only setting, but also PUDs and even PMDs. Give the function a more generic name to reflect that. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-16-git-send-email-joro@8bytes.org
2018-07-16x86/pti: Make pti_set_kernel_image_nonglobal() staticJiang Biao
pti_set_kernel_image_nonglobal() is only used in pti.c, make it static. Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: luto@kernel.org Cc: hpa@zytor.com Cc: albcamus@gmail.com Cc: zhong.weidong@zte.com.cn Link: https://lkml.kernel.org/r/1531713820-24544-4-git-send-email-jiang.biao2@zte.com.cn
2018-04-25x86/pti: Disallow global kernel text with RANDSTRUCTDave Hansen
commit 26d35ca6c3776784f8156e1d6f80cc60d9a2a915 RANDSTRUCT derives its hardening benefits from the attacker's lack of knowledge about the layout of kernel data structures. Keep the kernel image non-global in cases where RANDSTRUCT is in use to help keep the layout a secret. Fixes: 8c06c7740 (x86/pti: Leave kernel text global for !PCID) Reported-by: Kees Cook <keescook@google.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Nadav Amit <namit@vmware.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Link: https://lkml.kernel.org/r/20180420222026.D0B4AAC9@viggo.jf.intel.com
2018-04-25x86/pti: Reduce amount of kernel text allowed to be GlobalDave Hansen
commit abb67605203687c8b7943d760638d0301787f8d9 Kees reported to me that I made too much of the kernel image global. It was far more than just text: I think this is too much set global: _end is after data, bss, and brk, and all kinds of other stuff that could hold secrets. I think this should match what mark_rodata_ro() is doing. This does exactly that. We use __end_rodata_hpage_align as our marker both because it is huge-page-aligned and it does not contain any sections we expect to hold secrets. Kees's logic was that r/o data is in the kernel image anyway and, in the case of traditional distributions, can be freely downloaded from the web, so there's no reason to hide it. Fixes: 8c06c7740 (x86/pti: Leave kernel text global for !PCID) Reported-by: Kees Cook <keescook@google.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Nadav Amit <namit@vmware.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Link: https://lkml.kernel.org/r/20180420222023.1C8B2B20@viggo.jf.intel.com
2018-04-12x86/pti: Leave kernel text global for !PCIDDave Hansen
Global pages are bad for hardening because they potentially let an exploit read the kernel image via a Meltdown-style attack which makes it easier to find gadgets. But, global pages are good for performance because they reduce TLB misses when making user/kernel transitions, especially when PCIDs are not available, such as on older hardware, or where a hypervisor has disabled them for some reason. This patch implements a basic, sane policy: If you have PCIDs, you only map a minimal amount of kernel text global. If you do not have PCIDs, you map all kernel text global. This policy effectively makes PCIDs something that not only adds performance but a little bit of hardening as well. I ran a simple "lseek" microbenchmark[1] to test the benefit on a modern Atom microserver. Most of the benefit comes from applying the series before this patch ("entry only"), but there is still a signifiant benefit from this patch. No Global Lines (baseline ): 6077741 lseeks/sec 88 Global Lines (entry only): 7528609 lseeks/sec (+23.9%) 94 Global Lines (this patch): 8433111 lseeks/sec (+38.8%) [1.] https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205518.E3D989EB@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-12x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel imageDave Hansen
Summary: In current kernels, with PTI enabled, no pages are marked Global. This potentially increases TLB misses. But, the mechanism by which the Global bit is set and cleared is rather haphazard. This patch makes the process more explicit. In the end, it leaves us with Global entries in the page tables for the areas truly shared by userspace and kernel and increases TLB hit rates. The place this patch really shines in on systems without PCIDs. In this case, we are using an lseek microbenchmark[1] to see how a reasonably non-trivial syscall behaves. Higher is better: No Global pages (baseline): 6077741 lseeks/sec 88 Global Pages (this set): 7528609 lseeks/sec (+23.9%) On a modern Skylake desktop with PCIDs, the benefits are tangible, but not huge for a kernel compile (lower is better): No Global pages (baseline): 186.951 seconds time elapsed ( +- 0.35% ) 28 Global pages (this set): 185.756 seconds time elapsed ( +- 0.09% ) -1.195 seconds (-0.64%) I also re-checked everything using the lseek1 test[1]: No Global pages (baseline): 15783951 lseeks/sec 28 Global pages (this set): 16054688 lseeks/sec +270737 lseeks/sec (+1.71%) The effect is more visible, but still modest. Details: The kernel page tables are inherited from head_64.S which rudely marks them as _PAGE_GLOBAL. For PTI, we have been relying on the grace of $DEITY and some insane behavior in pageattr.c to clear _PAGE_GLOBAL. This patch tries to do better. First, stop filtering out "unsupported" bits from being cleared in the pageattr code. It's fine to filter out *setting* these bits but it is insane to keep us from clearing them. Then, *explicitly* go clear _PAGE_GLOBAL from the kernel identity map. Do not rely on pageattr to do it magically. After this patch, we can see that "GLB" shows up in each copy of the page tables, that we have the same number of global entries in each and that they are the *same* entries. /sys/kernel/debug/page_tables/current_kernel:11 /sys/kernel/debug/page_tables/current_user:11 /sys/kernel/debug/page_tables/kernel:11 9caae8ad6a1fb53aca2407ec037f612d current_kernel.GLB 9caae8ad6a1fb53aca2407ec037f612d current_user.GLB 9caae8ad6a1fb53aca2407ec037f612d kernel.GLB A quick visual audit also shows that all the entries make sense. 0xfffffe0000000000 is the cpu_entry_area and 0xffffffff81c00000 is the entry/exit text: 0xfffffe0000000000-0xfffffe0000002000 8K ro GLB NX pte 0xfffffe0000002000-0xfffffe0000003000 4K RW GLB NX pte 0xfffffe0000003000-0xfffffe0000006000 12K ro GLB NX pte 0xfffffe0000006000-0xfffffe0000007000 4K ro GLB x pte 0xfffffe0000007000-0xfffffe000000d000 24K RW GLB NX pte 0xfffffe000002d000-0xfffffe000002e000 4K ro GLB NX pte 0xfffffe000002e000-0xfffffe000002f000 4K RW GLB NX pte 0xfffffe000002f000-0xfffffe0000032000 12K ro GLB NX pte 0xfffffe0000032000-0xfffffe0000033000 4K ro GLB x pte 0xfffffe0000033000-0xfffffe0000039000 24K RW GLB NX pte 0xffffffff81c00000-0xffffffff81e00000 2M ro PSE GLB x pmd [1.] https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205517.C80FBE05@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-12x86/pti: Enable global pages for shared areasDave Hansen
The entry/exit text and cpu_entry_area are mapped into userspace and the kernel. But, they are not _PAGE_GLOBAL. This creates unnecessary TLB misses. Add the _PAGE_GLOBAL flag for these areas. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205515.2977EE7D@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-08x86/pti: Fix a comment typoSeunghun Han
s/visinble/visible/ Signed-off-by: Seunghun Han <kkamagui@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1520397135-132809-1-git-send-email-kkamagui@gmail.com
2018-01-08x86/mm/pti: Remove dead logic in pti_user_pagetable_walk*()Jike Song
The following code contains dead logic: 162 if (pgd_none(*pgd)) { 163 unsigned long new_p4d_page = __get_free_page(gfp); 164 if (!new_p4d_page) 165 return NULL; 166 167 if (pgd_none(*pgd)) { 168 set_pgd(pgd, __pgd(_KERNPG_TABLE | __pa(new_p4d_page))); 169 new_p4d_page = 0; 170 } 171 if (new_p4d_page) 172 free_page(new_p4d_page); 173 } There can't be any difference between two pgd_none(*pgd) at L162 and L167, so it's always false at L171. Dave Hansen explained: Yes, the double-test was part of an optimization where we attempted to avoid using a global spinlock in the fork() path. We would check for unallocated mid-level page tables without the lock. The lock was only taken when we needed to *make* an entry to avoid collisions. Now that it is all single-threaded, there is no chance of a collision, no need for a lock, and no need for the re-check. As all these functions are only called during init, mark them __init as well. Fixes: 03f4424f348e ("x86/mm/pti: Add functions to clone kernel PMDs") Signed-off-by: Jike Song <albcamus@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Andi Kleen <ak@linux.intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Jiri Koshina <jikos@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Kees Cook <keescook@google.com> Cc: Andi Lutomirski <luto@amacapital.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Greg KH <gregkh@linux-foundation.org> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Paul Turner <pjt@google.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180108160341.3461-1-albcamus@gmail.com
2018-01-05x86/pti: Rename BUG_CPU_INSECURE to BUG_CPU_MELTDOWNThomas Gleixner
Use the name associated with the particular attack which needs page table isolation for mitigation. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: David Woodhouse <dwmw@amazon.co.uk> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jiri Koshina <jikos@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Andi Lutomirski <luto@amacapital.net> Cc: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Turner <pjt@google.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Greg KH <gregkh@linux-foundation.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Kees Cook <keescook@google.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801051525300.1724@nanos
2018-01-03x86/pti: Make sure the user/kernel PTEs matchThomas Gleixner
Meelis reported that his K8 Athlon64 emits MCE warnings when PTI is enabled: [Hardware Error]: Error Addr: 0x0000ffff81e000e0 [Hardware Error]: MC1 Error: L1 TLB multimatch. [Hardware Error]: cache level: L1, tx: INSN The address is in the entry area, which is mapped into kernel _AND_ user space. That's special because we switch CR3 while we are executing there. User mapping: 0xffffffff81e00000-0xffffffff82000000 2M ro PSE GLB x pmd Kernel mapping: 0xffffffff81000000-0xffffffff82000000 16M ro PSE x pmd So the K8 is complaining that the TLB entries differ. They differ in the GLB bit. Drop the GLB bit when installing the user shared mapping. Fixes: 6dc72c3cbca0 ("x86/mm/pti: Share entry text PMD") Reported-by: Meelis Roos <mroos@linux.ee> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Meelis Roos <mroos@linux.ee> Cc: Borislav Petkov <bp@alien8.de> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801031407180.1957@nanos
2017-12-23x86/pti: Map the vsyscall page if neededAndy Lutomirski
Make VSYSCALLs work fully in PTI mode by mapping them properly to the user space visible page tables. [ tglx: Hide unused functions (Patch by Arnd Bergmann) ] Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/mm/pti: Map ESPFIX into user spaceAndy Lutomirski
Map the ESPFIX pages into user space when PTI is enabled. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/mm/pti: Share entry text PMDThomas Gleixner
Share the entry text PMD of the kernel mapping with the user space mapping. If large pages are enabled this is a single PMD entry and at the point where it is copied into the user page table the RW bit has not been cleared yet. Clear it right away so the user space visible map becomes RX. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/mm/pti: Share cpu_entry_area with user space page tablesAndy Lutomirski
Share the cpu entry area so the user space and kernel space page tables have the same P4D page. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/mm/pti: Add functions to clone kernel PMDsAndy Lutomirski
Provide infrastructure to: - find a kernel PMD for a mapping which must be visible to user space for the entry/exit code to work. - walk an address range and share the kernel PMD with it. This reuses a small part of the original KAISER patches to populate the user space page table. [ tglx: Made it universally usable so it can be used for any kind of shared mapping. Add a mechanism to clear specific bits in the user space visible PMD entry. Folded Andys simplifactions ] Originally-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/mm/pti: Add mapping helper functionsDave Hansen
Add the pagetable helper functions do manage the separate user space page tables. [ tglx: Split out from the big combo kaiser patch. Folded Andys simplification and made it out of line as Boris suggested ] Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/pti: Add the pti= cmdline option and documentationBorislav Petkov
Keep the "nopti" optional for traditional reasons. [ tglx: Don't allow force on when running on XEN PV and made 'on' printout conditional ] Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirsky <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Link: https://lkml.kernel.org/r/20171212133952.10177-1-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23x86/mm/pti: Add infrastructure for page table isolationThomas Gleixner
Add the initial files for kernel page table isolation, with a minimal init function and the boot time detection for this misfeature. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>