linux/arch/x86/kernel/cpu/Makefile

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#
# Makefile for x86-compatible CPU details, features and quirks
#
# Don't trace early stages of a secondary CPU boot
ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_common.o = -pg
CFLAGS_REMOVE_perf_event.o = -pg
endif
kernel: add kcov code coverage 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 <dvyukov@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tavis Ormandy <taviso@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@google.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: David Drysdale <drysdale@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-22 21:27:30 +00:00
# If these files are instrumented, boot hangs during the first second.
KCOV_INSTRUMENT_common.o := n
KCOV_INSTRUMENT_perf_event.o := n
# Make sure load_percpu_segment has no stackprotector
nostackp := $(call cc-option, -fno-stack-protector)
CFLAGS_common.o := $(nostackp)
obj-y := intel_cacheinfo.o scattered.o topology.o
obj-y += common.o
obj-y += rdrand.o
Add driver auto probing for x86 features v4 There's a growing number of drivers that support a specific x86 feature or CPU. Currently loading these drivers currently on a generic distribution requires various driver specific hacks and it often doesn't work. This patch adds auto probing for drivers based on the x86 cpuid information, in particular based on vendor/family/model number and also based on CPUID feature bits. For example a common issue is not loading the SSE 4.2 accelerated CRC module: this can significantly lower the performance of BTRFS which relies on fast CRC. Another issue is loading the right CPUFREQ driver for the current CPU. Currently distributions often try all all possible driver until one sticks, which is not really a good way to do this. It works with existing udev without any changes. The code exports the x86 information as a generic string in sysfs that can be matched by udev's pattern matching. This scheme does not support numeric ranges, so if you want to handle e.g. ranges of model numbers they have to be encoded in ASCII or simply all models or families listed. Fixing that would require changing udev. Another issue is that udev will happily load all drivers that match, there is currently no nice way to stop a specific driver from being loaded if it's not needed (e.g. if you don't need fast CRC) But there are not that many cpu specific drivers around and they're all not that bloated, so this isn't a particularly serious issue. Originally this patch added the modalias to the normal cpu sysdevs. However sysdevs don't have all the infrastructure needed for udev, so it couldn't really autoload drivers. This patch instead adds the CPU modaliases to the cpuid devices, which are real devices with full support for udev. This implies that the cpuid driver has to be loaded to use this. This patch just adds infrastructure, some driver conversions in followups. Thanks to Kay for helping with some sysfs magic. v2: Constifcation, some updates v4: (trenn@suse.de): - Use kzalloc instead of kmalloc to terminate modalias buffer - Use uppercase hex values to match correctly against hex values containing letters Cc: Dave Jones <davej@redhat.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jen Axboe <axboe@kernel.dk> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Huang Ying <ying.huang@intel.com> Cc: Len Brown <lenb@kernel.org> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Thomas Renninger <trenn@suse.de> Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2012-01-25 23:09:05 +00:00
obj-y += match.o
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o
obj-$(CONFIG_X86_32) += bugs.o
obj-$(CONFIG_X86_64) += bugs_64.o
obj-$(CONFIG_CPU_SUP_INTEL) += intel.o
obj-$(CONFIG_CPU_SUP_AMD) += amd.o
obj-$(CONFIG_CPU_SUP_CYRIX_32) += cyrix.o
obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o
obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o
obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o
obj-$(CONFIG_X86_MCE) += mcheck/
obj-$(CONFIG_MTRR) += mtrr/
obj-$(CONFIG_MICROCODE) += microcode/
obj-$(CONFIG_X86_LOCAL_APIC) += perfctr-watchdog.o
obj-$(CONFIG_HYPERVISOR_GUEST) += vmware.o hypervisor.o mshyperv.o
ifdef CONFIG_X86_FEATURE_NAMES
quiet_cmd_mkcapflags = MKCAP $@
cmd_mkcapflags = $(CONFIG_SHELL) $(srctree)/$(src)/mkcapflags.sh $< $@
cpufeature = $(src)/../../include/asm/cpufeatures.h
targets += capflags.c
$(obj)/capflags.c: $(cpufeature) $(src)/mkcapflags.sh FORCE
$(call if_changed,mkcapflags)
endif
clean-files += capflags.c