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Commit 7c464151 authored by Linux Build Service Account's avatar Linux Build Service Account Committed by Gerrit - the friendly Code Review server
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Merge "Merge android-3.18.123 (e5902aa2) into msm-3.18"

parents f47a4012 ca00e471

Documentation/kcov.txt

deleted100644 → 0
+0 −111
Original line number Diff line number Diff line 
kcov: code coverage for fuzzing

===============================



kcov exposes kernel code coverage information in a form suitable for coverage-

guided fuzzing (randomized testing). Coverage data of a running kernel is

exported via the "kcov" debugfs file. Coverage collection is enabled on a task

basis, and thus it can capture precise coverage of a single system call.



Note that 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 parts of kernel is

disbled (e.g. scheduler, locking).



Usage:

======



Configure kernel with:



        CONFIG_KCOV=y



CONFIG_KCOV requires gcc built on revision 231296 or later.

Profiling data will only become accessible once debugfs has been mounted:



        mount -t debugfs none /sys/kernel/debug



The following program demonstrates kcov usage from within a test program:



#include <stdio.h>

#include <stddef.h>

#include <stdint.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/ioctl.h>

#include <sys/mman.h>

#include <unistd.h>

#include <fcntl.h>



#define KCOV_INIT_TRACE			_IOR('c', 1, unsigned long)

#define KCOV_ENABLE			_IO('c', 100)

#define KCOV_DISABLE			_IO('c', 101)

#define COVER_SIZE			(64<<10)



int main(int argc, char **argv)

{

	int fd;

	unsigned long *cover, n, i;



	/* A single fd descriptor allows coverage collection on a single

	 * thread.

	 */

	fd = open("/sys/kernel/debug/kcov", O_RDWR);

	if (fd == -1)

		perror("open"), exit(1);

	/* Setup trace mode and trace size. */

	if (ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE))

		perror("ioctl"), exit(1);

	/* Mmap buffer shared between kernel- and user-space. */

	cover = (unsigned long*)mmap(NULL, COVER_SIZE * sizeof(unsigned long),

				     PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

	if ((void*)cover == MAP_FAILED)

		perror("mmap"), exit(1);

	/* Enable coverage collection on the current thread. */

	if (ioctl(fd, KCOV_ENABLE, 0))

		perror("ioctl"), exit(1);

	/* Reset coverage from the tail of the ioctl() call. */

	__atomic_store_n(&cover[0], 0, __ATOMIC_RELAXED);

	/* That's the target syscal call. */

	read(-1, NULL, 0);

	/* Read number of PCs collected. */

	n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED);

	for (i = 0; i < n; i++)

		printf("0x%lx\n", cover[i + 1]);

	/* Disable coverage collection for the current thread. After this call

	 * coverage can be enabled for a different thread.

	 */

	if (ioctl(fd, KCOV_DISABLE, 0))

		perror("ioctl"), exit(1);

	/* Free resources. */

	if (munmap(cover, COVER_SIZE * sizeof(unsigned long)))

		perror("munmap"), exit(1);

	if (close(fd))

		perror("close"), exit(1);

	return 0;

}



After piping through addr2line output of the program looks as follows:



SyS_read

fs/read_write.c:562

__fdget_pos

fs/file.c:774

__fget_light

fs/file.c:746

__fget_light

fs/file.c:750

__fget_light

fs/file.c:760

__fdget_pos

fs/file.c:784

SyS_read

fs/read_write.c:562



If a program needs to collect coverage from several threads (independently),

it needs to open /sys/kernel/debug/kcov in each thread separately.



The interface is fine-grained to allow efficient forking of test processes.

That is, a parent process opens /sys/kernel/debug/kcov, enables trace mode,

mmaps coverage buffer and then forks child processes in a loop. Child processes

only need to enable coverage (disable happens automatically on thread end).

Makefile

+2 −12
Original line number Diff line number Diff line 
VERSION = 3

PATCHLEVEL = 18

SUBLEVEL = 122

SUBLEVEL = 123

EXTRAVERSION =

NAME = Diseased Newt
@@ -380,8 +380,6 @@ LDFLAGS_MODULE = 
CFLAGS_KERNEL	=

AFLAGS_KERNEL	=

CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im

CFLAGS_KCOV	= -fsanitize-coverage=trace-pc





# Use USERINCLUDE when you must reference the UAPI directories only.

USERINCLUDE    := \
@@ -426,7 +424,7 @@ export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE 
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS



export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS

export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KCOV CFLAGS_KASAN CFLAGS_UBSAN

export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV

export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE

export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE

export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
@@ -682,14 +680,6 @@ endif 
endif

KBUILD_CFLAGS += $(stackp-flag)



ifdef CONFIG_KCOV

  ifeq ($(call cc-option, $(CFLAGS_KCOV)),)

    $(warning Cannot use CONFIG_KCOV: \

             -fsanitize-coverage=trace-pc is not supported by compiler)

    CFLAGS_KCOV =

  endif

endif



ifeq ($(COMPILER),clang)

KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)

KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)

arch/arm/kernel/entry-common.S

+7 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <asm/unistd.h>

#include <asm/ftrace.h>

#include <asm/unwind.h>

#include <asm/memory.h>



#ifdef CONFIG_NEED_RET_TO_USER

#include <mach/entry-macro.S>
@@ -33,6 +34,9 @@ ret_fast_syscall: 
 UNWIND(.fnstart	)

 UNWIND(.cantunwind	)

	disable_irq				@ disable interrupts

	ldr	r2, [tsk, #TI_ADDR_LIMIT]

	cmp	r2, #TASK_SIZE

	blne	addr_limit_check_failed

	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing

	tst	r1, #_TIF_SYSCALL_WORK

	bne	__sys_trace_return
@@ -69,6 +73,9 @@ ENTRY(ret_to_user) 
ret_slow_syscall:

	disable_irq				@ disable interrupts

ENTRY(ret_to_user_from_irq)

	ldr	r2, [tsk, #TI_ADDR_LIMIT]

	cmp	r2, #TASK_SIZE

	blne	addr_limit_check_failed

	ldr	r1, [tsk, #TI_FLAGS]

	tst	r1, #_TIF_WORK_MASK

	bne	work_pending

arch/arm/kernel/signal.c

+7 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/uaccess.h>

#include <linux/tracehook.h>

#include <linux/uprobes.h>

#include <linux/syscalls.h>



#include <asm/elf.h>

#include <asm/cacheflush.h>
@@ -639,3 +640,9 @@ struct page *get_signal_page(void) 


	return page;

}



/* Defer to generic check */

asmlinkage void addr_limit_check_failed(void)

{

	addr_limit_user_check();

}

arch/arm/mach-hisi/hotplug.c

+22 −11
Original line number Diff line number Diff line
@@ -145,14 +145,21 @@ static int hi3xxx_hotplug_init(void) 
	struct device_node *node;



	node = of_find_compatible_node(NULL, NULL, "hisilicon,sysctrl");

	if (node) {

	if (!node) {

		id = ERROR_CTRL;

		return -ENOENT;

	}



	ctrl_base = of_iomap(node, 0);

	of_node_put(node);

	if (!ctrl_base) {

		id = ERROR_CTRL;

		return -ENOMEM;

	}



	id = HI3620_CTRL;

	return 0;

}

	id = ERROR_CTRL;

	return -ENOENT;

}



void hi3xxx_set_cpu(int cpu, bool enable)

{
@@ -170,11 +177,15 @@ static bool hix5hd2_hotplug_init(void) 
	struct device_node *np;



	np = of_find_compatible_node(NULL, NULL, "hisilicon,cpuctrl");

	if (np) {

	if (!np)

		return false;



	ctrl_base = of_iomap(np, 0);

		return true;

	}

	of_node_put(np);

	if (!ctrl_base)

		return false;



	return true;

}



void hix5hd2_set_cpu(int cpu, bool enable)