BMC/Intel-BMC/linux.git/arch/x86/entry, branch dev-4.6

x86: Use compat version for preadv2 and pwritev2

2016-05-12T12:27:13+00:00

Similar to preadv and pwritev, preadv2 and pwritev2 need compat entries in the 32-bit syscall table. This bug was found by strace test suite. Fixes: 4babf2c5efb7 ("x86: wire up preadv2 and pwritev2") Signed-off-by: Dmitry V. Levin Acked-by: Christoph Hellwig Link: http://lkml.kernel.org/r/20160511084817.GA29823@altlinux.org Signed-off-by: Thomas Gleixner

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-03-24T16:47:32+00:00

Pull x86 fixes from Ingo Molnar: "Misc fixes: - fix hotplug bugs - fix irq live lock - fix various topology handling bugs - fix APIC ACK ordering - fix PV iopl handling - fix speling - fix/tweak memcpy_mcsafe() return value - fix fbcon bug - remove stray prototypes" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/msr: Remove unused native_read_tscp() x86/apic: Remove declaration of unused hw_nmi_is_cpu_stuck x86/oprofile/nmi: Add missing hotplug FROZEN handling x86/hpet: Use proper mask to modify hotplug action x86/apic/uv: Fix the hotplug notifier x86/apb/timer: Use proper mask to modify hotplug action x86/topology: Use total_cpus not nr_cpu_ids for logical packages x86/topology: Fix Intel HT disable x86/topology: Fix logical package mapping x86/irq: Cure live lock in fixup_irqs() x86/tsc: Prevent NULL pointer deref in calibrate_delay_is_known() x86/apic: Fix suspicious RCU usage in smp_trace_call_function_interrupt() x86/iopl: Fix iopl capability check on Xen PV x86/iopl/64: Properly context-switch IOPL on Xen PV selftests/x86: Add an iopl test x86/mm, x86/mce: Fix return type/value for memcpy_mcsafe() x86/video: Don't assume all FB devices are PCI devices arch/x86/irq: Purge useless handler declarations from hw_irq.h x86: Fix misspellings in comments

kernel: add kcov code coverage

2016-03-22T22:36:02+00:00

kcov provides code coverage collection for coverage-guided fuzzing (randomized testing). Coverage-guided fuzzing is a testing technique that uses coverage feedback to determine new interesting inputs to a system. A notable user-space example is AFL (http://lcamtuf.coredump.cx/afl/). However, this technique is not widely used for kernel testing due to missing compiler and kernel support. kcov does not aim to collect as much coverage as possible. It aims to collect more or less stable coverage that is function of syscall inputs. To achieve this goal it does not collect coverage in soft/hard interrupts and instrumentation of some inherently non-deterministic or non-interesting parts of kernel is disbled (e.g. scheduler, locking). Currently there is a single coverage collection mode (tracing), but the API anticipates additional collection modes. Initially I also implemented a second mode which exposes coverage in a fixed-size hash table of counters (what Quentin used in his original patch). I've dropped the second mode for simplicity. This patch adds the necessary support on kernel side. The complimentary compiler support was added in gcc revision 231296. We've used this support to build syzkaller system call fuzzer, which has found 90 kernel bugs in just 2 months: https://github.com/google/syzkaller/wiki/Found-Bugs We've also found 30+ bugs in our internal systems with syzkaller. Another (yet unexplored) direction where kcov coverage would greatly help is more traditional "blob mutation". For example, mounting a random blob as a filesystem, or receiving a random blob over wire. Why not gcov. Typical fuzzing loop looks as follows: (1) reset coverage, (2) execute a bit of code, (3) collect coverage, repeat. A typical coverage can be just a dozen of basic blocks (e.g. an invalid input). In such context gcov becomes prohibitively expensive as reset/collect coverage steps depend on total number of basic blocks/edges in program (in case of kernel it is about 2M). Cost of kcov depends only on number of executed basic blocks/edges. On top of that, kernel requires per-thread coverage because there are always background threads and unrelated processes that also produce coverage. With inlined gcov instrumentation per-thread coverage is not possible. kcov exposes kernel PCs and control flow to user-space which is insecure. But debugfs should not be mapped as user accessible. Based on a patch by Quentin Casasnovas. [akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode'] [akpm@linux-foundation.org: unbreak allmodconfig] [akpm@linux-foundation.org: follow x86 Makefile layout standards] Signed-off-by: Dmitry Vyukov Reviewed-by: Kees Cook Cc: syzkaller Cc: Vegard Nossum Cc: Catalin Marinas Cc: Tavis Ormandy Cc: Will Deacon Cc: Quentin Casasnovas Cc: Kostya Serebryany Cc: Eric Dumazet Cc: Alexander Potapenko Cc: Kees Cook Cc: Bjorn Helgaas Cc: Sasha Levin Cc: David Drysdale Cc: Ard Biesheuvel Cc: Andrey Ryabinin Cc: Kirill A. Shutemov Cc: Jiri Slaby Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-03-21T01:23:21+00:00

Pull 'objtool' stack frame validation from Ingo Molnar: "This tree adds a new kernel build-time object file validation feature (ONFIG_STACK_VALIDATION=y): kernel stack frame correctness validation. It was written by and is maintained by Josh Poimboeuf. The motivation: there's a category of hard to find kernel bugs, most of them in assembly code (but also occasionally in C code), that degrades the quality of kernel stack dumps/backtraces. These bugs are hard to detect at the source code level. Such bugs result in incorrect/incomplete backtraces most of time - but can also in some rare cases result in crashes or other undefined behavior. The build time correctness checking is done via the new 'objtool' user-space utility that was written for this purpose and which is hosted in the kernel repository in tools/objtool/. The tool's (very simple) UI and source code design is shaped after Git and perf and shares quite a bit of infrastructure with tools/perf (which tooling infrastructure sharing effort got merged via perf and is already upstream). Objtool follows the well-known kernel coding style. Objtool does not try to check .c or .S files, it instead analyzes the resulting .o generated machine code from first principles: it decodes the instruction stream and interprets it. (Right now objtool supports the x86-64 architecture.) From tools/objtool/Documentation/stack-validation.txt: "The kernel CONFIG_STACK_VALIDATION option enables a host tool named objtool which runs at compile time. It has a "check" subcommand which analyzes every .o file and ensures the validity of its stack metadata. It enforces a set of rules on asm code and C inline assembly code so that stack traces can be reliable. Currently it only checks frame pointer usage, but there are plans to add CFI validation for C files and CFI generation for asm files. For each function, it recursively follows all possible code paths and validates the correct frame pointer state at each instruction. It also follows code paths involving special sections, like .altinstructions, __jump_table, and __ex_table, which can add alternative execution paths to a given instruction (or set of instructions). Similarly, it knows how to follow switch statements, for which gcc sometimes uses jump tables." When this new kernel option is enabled (it's disabled by default), the tool, if it finds any suspicious assembly code pattern, outputs warnings in compiler warning format: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup warning: objtool:__schedule()+0x3c0: duplicate frame pointer save warning: objtool:__schedule()+0x3fd: sibling call from callable instruction with changed frame pointer ... so that scripts that pick up compiler warnings will notice them. All known warnings triggered by the tool are fixed by the tree, most of the commits in fact prepare the kernel to be warning-free. Most of them are bugfixes or cleanups that stand on their own, but there are also some annotations of 'special' stack frames for justified cases such entries to JIT-ed code (BPF) or really special boot time code. There are two other long-term motivations behind this tool as well: - To improve the quality and reliability of kernel stack frames, so that they can be used for optimized live patching. - To create independent infrastructure to check the correctness of CFI stack frames at build time. CFI debuginfo is notoriously unreliable and we cannot use it in the kernel as-is without extra checking done both on the kernel side and on the build side. The quality of kernel stack frames matters to debuggability as well, so IMO we can merge this without having to consider the live patching or CFI debuginfo angle" * 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits) objtool: Only print one warning per function objtool: Add several performance improvements tools: Copy hashtable.h into tools directory objtool: Fix false positive warnings for functions with multiple switch statements objtool: Rename some variables and functions objtool: Remove superflous INIT_LIST_HEAD objtool: Add helper macros for traversing instructions objtool: Fix false positive warnings related to sibling calls objtool: Compile with debugging symbols objtool: Detect infinite recursion objtool: Prevent infinite recursion in noreturn detection objtool: Detect and warn if libelf is missing and don't break the build tools: Support relative directory path for 'O=' objtool: Support CROSS_COMPILE x86/asm/decoder: Use explicitly signed chars objtool: Enable stack metadata validation on 64-bit x86 objtool: Add CONFIG_STACK_VALIDATION option objtool: Add tool to perform compile-time stack metadata validation x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard sched: Always inline context_switch() ...

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2016-03-20T01:52:29+00:00

Pull vfs updates from Al Viro: - Preparations of parallel lookups (the remaining main obstacle is the need to move security_d_instantiate(); once that becomes safe, the rest will be a matter of rather short series local to fs/*.c - preadv2/pwritev2 series from Christoph - assorted fixes * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (32 commits) splice: handle zero nr_pages in splice_to_pipe() vfs: show_vfsstat: do not ignore errors from show_devname method dcache.c: new helper: __d_add() don't bother with __d_instantiate(dentry, NULL) untangle fsnotify_d_instantiate() a bit uninline d_add() replace d_add_unique() with saner primitive quota: use lookup_one_len_unlocked() cifs_get_root(): use lookup_one_len_unlocked() nfs_lookup: don't bother with d_instantiate(dentry, NULL) kill dentry_unhash() ceph_fill_trace(): don't bother with d_instantiate(dn, NULL) autofs4: don't bother with d_instantiate(dentry, NULL) in ->lookup() configfs: move d_rehash() into configfs_create() for regular files ceph: don't bother with d_rehash() in splice_dentry() namei: teach lookup_slow() to skip revalidate namei: massage lookup_slow() to be usable by lookup_one_len_unlocked() lookup_one_len_unlocked(): use lookup_dcache() namei: simplify invalidation logics in lookup_dcache() namei: change calling conventions for lookup_{fast,slow} and follow_managed() ...

Merge branch 'x86/cleanups' into x86/urgent

2016-03-17T08:44:57+00:00

Pull in some merge window leftovers. Signed-off-by: Ingo Molnar

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-03-15T16:32:27+00:00

Pull x86 asm updates from Ingo Molnar: "This is another big update. Main changes are: - lots of x86 system call (and other traps/exceptions) entry code enhancements. In particular the complex parts of the 64-bit entry code have been migrated to C code as well, and a number of dusty corners have been refreshed. (Andy Lutomirski) - vDSO special mapping robustification and general cleanups (Andy Lutomirski) - cpufeature refactoring, cleanups and speedups (Borislav Petkov) - lots of other changes ..." * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits) x86/cpufeature: Enable new AVX-512 features x86/entry/traps: Show unhandled signal for i386 in do_trap() x86/entry: Call enter_from_user_mode() with IRQs off x86/entry/32: Change INT80 to be an interrupt gate x86/entry: Improve system call entry comments x86/entry: Remove TIF_SINGLESTEP entry work x86/entry/32: Add and check a stack canary for the SYSENTER stack x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup x86/entry: Only allocate space for tss_struct::SYSENTER_stack if needed x86/entry: Vastly simplify SYSENTER TF (single-step) handling x86/entry/traps: Clear DR6 early in do_debug() and improve the comment x86/entry/traps: Clear TIF_BLOCKSTEP on all debug exceptions x86/entry/32: Restore FLAGS on SYSEXIT x86/entry/32: Filter NT and speed up AC filtering in SYSENTER x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test selftests/x86: In syscall_nt, test NT|TF as well x86/asm-offsets: Remove PARAVIRT_enabled x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled uprobes: __create_xol_area() must nullify xol_mapping.fault x86/cpufeature: Create a new synthetic cpu capability for machine check recovery ...

Merge branch 'mm-readonly-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-03-14T23:58:50+00:00

Pull read-only kernel memory updates from Ingo Molnar: "This tree adds two (security related) enhancements to the kernel's handling of read-only kernel memory: - extend read-only kernel memory to a new class of formerly writable kernel data: 'post-init read-only memory' via the __ro_after_init attribute, and mark the ARM and x86 vDSO as such read-only memory. This kind of attribute can be used for data that requires a once per bootup initialization sequence, but is otherwise never modified after that point. This feature was based on the work by PaX Team and Brad Spengler. (by Kees Cook, the ARM vDSO bits by David Brown.) - make CONFIG_DEBUG_RODATA always enabled on x86 and remove the Kconfig option. This simplifies the kernel and also signals that read-only memory is the default model and a first-class citizen. (Kees Cook)" * 'mm-readonly-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: ARM/vdso: Mark the vDSO code read-only after init x86/vdso: Mark the vDSO code read-only after init lkdtm: Verify that '__ro_after_init' works correctly arch: Introduce post-init read-only memory x86/mm: Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings asm-generic: Consolidate mark_rodata_ro()

x86/entry: Call enter_from_user_mode() with IRQs off

2016-03-10T09:53:26+00:00

Now that slow-path syscalls always enter C before enabling interrupts, it's straightforward to call enter_from_user_mode() before enabling interrupts rather than doing it as part of entry tracing. With this change, we should finally be able to retire exception_enter(). This will also enable optimizations based on knowing that we never change context tracking state with interrupts on. Signed-off-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Frédéric Weisbecker Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/bc376ecf87921a495e874ff98139b1ca2f5c5dd7.1457558566.git.luto@kernel.org Signed-off-by: Ingo Molnar

x86/entry/32: Change INT80 to be an interrupt gate

2016-03-10T09:53:26+00:00

We want all of the syscall entries to run with interrupts off so that we can efficiently run context tracking before enabling interrupts. This will regress int $0x80 performance on 32-bit kernels by a couple of cycles. This shouldn't matter much -- int $0x80 is not a fast path. This effectively reverts: 657c1eea0019 ("x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on") ... and fixes the same issue differently. Signed-off-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Frédéric Weisbecker Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/59b4f90c9ebfccd8c937305dbbbca680bc74b905.1457558566.git.luto@kernel.org Signed-off-by: Ingo Molnar