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

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

x86/cpu: Unify CPU family, model, stepping calculation

2015-11-24T08:15:54+00:00

Add generic functions which calc family, model and stepping from the CPUID_1.EAX leaf and stick them into the library we have. Rename those which do call CPUID with the prefix "x86_cpuid" as suggested by Paolo Bonzini. No functionality change. Signed-off-by: Borislav Petkov Reviewed-by: Paolo Bonzini Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1448273546-2567-2-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar

x86/asm/entry: Move the 'thunk' functions to arch/x86/entry/

2015-06-04T05:37:33+00:00

These are all calling x86 entry code functions, so move them close to other entry code. Change lib-y to obj-y: there's no real difference between the two as we don't really drop any of them during the linking stage, and obj-y is the more common approach for core kernel object code. Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Thomas Gleixner Cc: Andy Lutomirski Cc: Denys Vlasenko Cc: Brian Gerst Cc: Peter Zijlstra Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

x86/asm/uaccess: Get rid of copy_user_nocache_64.S

2015-05-14T05:25:35+00:00

Move __copy_user_nocache() to arch/x86/lib/copy_user_64.S and kill the containing file. No functionality change. Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1431538944-27724-4-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar

net, lib: kill arch_fast_hash library bits

2014-12-10T20:17:46+00:00

As there are now no remaining users of arch_fast_hash(), lets kill it entirely. This basically reverts commit 71ae8aac3e19 ("lib: introduce arch optimized hash library") and follow-up work, that is f.e., commit 237217546d44 ("lib: hash: follow-up fixups for arch hash"), commit e3fec2f74f7f ("lib: Add missing arch generic-y entries for asm-generic/hash.h") and last but not least commit 6a02652df511 ("perf tools: Fix include for non x86 architectures"). Cc: Francesco Fusco Cc: Thomas Graf Cc: Arnaldo Carvalho de Melo Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

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

2014-10-13T16:14:50+00:00

Pull x86 asm updates from Ingo Molnar: "The changes in this cycle were: - Speed up the x86 __preempt_schedule() implementation - Fix/improve low level asm code debug info annotations" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86: Unwind-annotate thunk_32.S x86: Improve cmpxchg8b_emu.S x86: Improve cmpxchg16b_emu.S x86/lib/Makefile: Remove the unnecessary "+= thunk_64.o" x86: Speed up ___preempt_schedule*() by using THUNK helpers

x86/lib/Makefile: Remove the unnecessary "+= thunk_64.o"

2014-09-24T13:15:39+00:00

Trivial. We have "lib-y += thunk_$(BITS).o" at the start, no need to add thunk_64.o if !CONFIG_X86_32. Signed-off-by: Oleg Nesterov Acked-by: Andy Lutomirski Cc: Denys Vlasenko Cc: Peter Zijlstra Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20140921184232.GB23727@redhat.com Signed-off-by: Ingo Molnar

locking/rwlock, x86: Delete unused asm/rwlock.h and rwlock.S

2014-09-10T09:46:39+00:00

This patch removes the unused asm/rwlock.h and rwlock.S files. Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Link: http://lkml.kernel.org/r/1408037251-45918-3-git-send-email-Waiman.Long@hp.com Cc: Scott J Norton Cc: Borislav Petkov Cc: Daniel Borkmann Cc: David S. Miller Cc: Francesco Fusco Cc: Linus Torvalds Cc: Thomas Graf Signed-off-by: Ingo Molnar

x86, boot: Carve out early cmdline parsing function

2014-05-21T03:21:24+00:00

Carve out early cmdline parsing function into .../lib/cmdline.c so it can be used by early code in the kernel proper as well. Adapted from arch/x86/boot/cmdline.c. Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/1400525957-11525-2-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin

lib: introduce arch optimized hash library

2013-12-17T19:27:17+00:00

We introduce a new hashing library that is meant to be used in the contexts where speed is more important than uniformity of the hashed values. The hash library leverages architecture specific implementation to achieve high performance and fall backs to jhash() for the generic case. On Intel-based x86 architectures, the library can exploit the crc32l instruction, part of the Intel SSE4.2 instruction set, if the instruction is supported by the processor. This implementation is twice as fast as the jhash() implementation on an i7 processor. Additional architectures, such as Arm64 provide instructions for accelerating the computation of CRC, so they could be added as well in follow-up work. Signed-off-by: Francesco Fusco Signed-off-by: Daniel Borkmann Signed-off-by: Thomas Graf Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller