Commit 85bbddc3 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Linus Torvalds
Browse files

selftests: new x86 breakpoints selftest 



Bring a first selftest in the relevant directory.  This tests several
combinations of breakpoints and watchpoints in x86, as well as icebp traps
and int3 traps.  Given the amount of breakpoint regressions we raised
after we merged the generic breakpoint infrastructure, such selftest
became necessary and can still serve today as a basis for new patches that
touch the do_debug() path.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 274343ad

tools/testing/selftests/Makefile

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TARGETS =

TARGETS = breakpoints



all:

	for TARGET in $(TARGETS); do \

tools/testing/selftests/breakpoints/Makefile

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# Taken from perf makefile

uname_M := $(shell uname -m 2>/dev/null || echo not)

ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)

ifeq ($(ARCH),i386)

        ARCH := x86

endif

ifeq ($(ARCH),x86_64)

	ARCH := x86

endif





all:

ifeq ($(ARCH),x86)

	gcc breakpoint_test.c -o run_test

else

	echo "Not an x86 target, can't build breakpoints selftests"

endif



clean:

	rm -fr run_test

tools/testing/selftests/breakpoints/breakpoint_test.c

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/*

 * Copyright (C) 2011 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>

 *

 * Licensed under the terms of the GNU GPL License version 2

 *

 * Selftests for breakpoints (and more generally the do_debug() path) in x86.

 */





#include <sys/ptrace.h>

#include <unistd.h>

#include <stddef.h>

#include <sys/user.h>

#include <stdio.h>

#include <stdlib.h>

#include <signal.h>

#include <sys/types.h>

#include <sys/wait.h>





/* Breakpoint access modes */

enum {

	BP_X = 1,

	BP_RW = 2,

	BP_W = 4,

};



static pid_t child_pid;



/*

 * Ensures the child and parent are always "talking" about

 * the same test sequence. (ie: that we haven't forgotten

 * to call check_trapped() somewhere).

 */

static int nr_tests;



static void set_breakpoint_addr(void *addr, int n)

{

	int ret;



	ret = ptrace(PTRACE_POKEUSER, child_pid,

		     offsetof(struct user, u_debugreg[n]), addr);

	if (ret) {

		perror("Can't set breakpoint addr\n");

		exit(-1);

	}

}



static void toggle_breakpoint(int n, int type, int len,

			      int local, int global, int set)

{

	int ret;



	int xtype, xlen;

	unsigned long vdr7, dr7;



	switch (type) {

	case BP_X:

		xtype = 0;

		break;

	case BP_W:

		xtype = 1;

		break;

	case BP_RW:

		xtype = 3;

		break;

	}



	switch (len) {

	case 1:

		xlen = 0;

		break;

	case 2:

		xlen = 4;

		break;

	case 4:

		xlen = 0xc;

		break;

	case 8:

		xlen = 8;

		break;

	}



	dr7 = ptrace(PTRACE_PEEKUSER, child_pid,

		     offsetof(struct user, u_debugreg[7]), 0);



	vdr7 = (xlen | xtype) << 16;

	vdr7 <<= 4 * n;



	if (local) {

		vdr7 |= 1 << (2 * n);

		vdr7 |= 1 << 8;

	}

	if (global) {

		vdr7 |= 2 << (2 * n);

		vdr7 |= 1 << 9;

	}



	if (set)

		dr7 |= vdr7;

	else

		dr7 &= ~vdr7;



	ret = ptrace(PTRACE_POKEUSER, child_pid,

		     offsetof(struct user, u_debugreg[7]), dr7);

	if (ret) {

		perror("Can't set dr7");

		exit(-1);

	}

}



/* Dummy variables to test read/write accesses */

static unsigned long long dummy_var[4];



/* Dummy functions to test execution accesses */

static void dummy_func(void) { }

static void dummy_func1(void) { }

static void dummy_func2(void) { }

static void dummy_func3(void) { }



static void (*dummy_funcs[])(void) = {

	dummy_func,

	dummy_func1,

	dummy_func2,

	dummy_func3,

};



static int trapped;



static void check_trapped(void)

{

	/*

	 * If we haven't trapped, wake up the parent

	 * so that it notices the failure.

	 */

	if (!trapped)

		kill(getpid(), SIGUSR1);

	trapped = 0;



	nr_tests++;

}



static void write_var(int len)

{

	char *pcval; short *psval; int *pival; long long *plval;

	int i;



	for (i = 0; i < 4; i++) {

		switch (len) {

		case 1:

			pcval = (char *)&dummy_var[i];

			*pcval = 0xff;

			break;

		case 2:

			psval = (short *)&dummy_var[i];

			*psval = 0xffff;

			break;

		case 4:

			pival = (int *)&dummy_var[i];

			*pival = 0xffffffff;

			break;

		case 8:

			plval = (long long *)&dummy_var[i];

			*plval = 0xffffffffffffffffLL;

			break;

		}

		check_trapped();

	}

}



static void read_var(int len)

{

	char cval; short sval; int ival; long long lval;

	int i;



	for (i = 0; i < 4; i++) {

		switch (len) {

		case 1:

			cval = *(char *)&dummy_var[i];

			break;

		case 2:

			sval = *(short *)&dummy_var[i];

			break;

		case 4:

			ival = *(int *)&dummy_var[i];

			break;

		case 8:

			lval = *(long long *)&dummy_var[i];

			break;

		}

		check_trapped();

	}

}



/*

 * Do the r/w/x accesses to trigger the breakpoints. And run

 * the usual traps.

 */

static void trigger_tests(void)

{

	int len, local, global, i;

	char val;

	int ret;



	ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);

	if (ret) {

		perror("Can't be traced?\n");

		return;

	}



	/* Wake up father so that it sets up the first test */

	kill(getpid(), SIGUSR1);



	/* Test instruction breakpoints */

	for (local = 0; local < 2; local++) {

		for (global = 0; global < 2; global++) {

			if (!local && !global)

				continue;



			for (i = 0; i < 4; i++) {

				dummy_funcs[i]();

				check_trapped();

			}

		}

	}



	/* Test write watchpoints */

	for (len = 1; len <= sizeof(long); len <<= 1) {

		for (local = 0; local < 2; local++) {

			for (global = 0; global < 2; global++) {

				if (!local && !global)

					continue;

				write_var(len);

			}

		}

	}



	/* Test read/write watchpoints (on read accesses) */

	for (len = 1; len <= sizeof(long); len <<= 1) {

		for (local = 0; local < 2; local++) {

			for (global = 0; global < 2; global++) {

				if (!local && !global)

					continue;

				read_var(len);

			}

		}

	}



	/* Icebp trap */

	asm(".byte 0xf1\n");

	check_trapped();



	/* Int 3 trap */

	asm("int $3\n");

	check_trapped();



	kill(getpid(), SIGUSR1);

}



static void check_success(const char *msg)

{

	const char *msg2;

	int child_nr_tests;

	int status;



	/* Wait for the child to SIGTRAP */

	wait(&status);



	msg2 = "Failed";



	if (WSTOPSIG(status) == SIGTRAP) {

		child_nr_tests = ptrace(PTRACE_PEEKDATA, child_pid,

					&nr_tests, 0);

		if (child_nr_tests == nr_tests)

			msg2 = "Ok";

		if (ptrace(PTRACE_POKEDATA, child_pid, &trapped, 1)) {

			perror("Can't poke\n");

			exit(-1);

		}

	}



	nr_tests++;



	printf("%s [%s]\n", msg, msg2);

}



static void launch_instruction_breakpoints(char *buf, int local, int global)

{

	int i;



	for (i = 0; i < 4; i++) {

		set_breakpoint_addr(dummy_funcs[i], i);

		toggle_breakpoint(i, BP_X, 1, local, global, 1);

		ptrace(PTRACE_CONT, child_pid, NULL, 0);

		sprintf(buf, "Test breakpoint %d with local: %d global: %d",

			i, local, global);

		check_success(buf);

		toggle_breakpoint(i, BP_X, 1, local, global, 0);

	}

}



static void launch_watchpoints(char *buf, int mode, int len,

			       int local, int global)

{

	const char *mode_str;

	int i;



	if (mode == BP_W)

		mode_str = "write";

	else

		mode_str = "read";



	for (i = 0; i < 4; i++) {

		set_breakpoint_addr(&dummy_var[i], i);

		toggle_breakpoint(i, mode, len, local, global, 1);

		ptrace(PTRACE_CONT, child_pid, NULL, 0);

		sprintf(buf, "Test %s watchpoint %d with len: %d local: "

			"%d global: %d", mode_str, i, len, local, global);

		check_success(buf);

		toggle_breakpoint(i, mode, len, local, global, 0);

	}

}



/* Set the breakpoints and check the child successfully trigger them */

static void launch_tests(void)

{

	char buf[1024];

	int len, local, global, i;



	/* Instruction breakpoints */

	for (local = 0; local < 2; local++) {

		for (global = 0; global < 2; global++) {

			if (!local && !global)

				continue;

			launch_instruction_breakpoints(buf, local, global);

		}

	}



	/* Write watchpoint */

	for (len = 1; len <= sizeof(long); len <<= 1) {

		for (local = 0; local < 2; local++) {

			for (global = 0; global < 2; global++) {

				if (!local && !global)

					continue;

				launch_watchpoints(buf, BP_W, len,

						   local, global);

			}

		}

	}



	/* Read-Write watchpoint */

	for (len = 1; len <= sizeof(long); len <<= 1) {

		for (local = 0; local < 2; local++) {

			for (global = 0; global < 2; global++) {

				if (!local && !global)

					continue;

				launch_watchpoints(buf, BP_RW, len,

						   local, global);

			}

		}

	}



	/* Icebp traps */

	ptrace(PTRACE_CONT, child_pid, NULL, 0);

	check_success("Test icebp");



	/* Int 3 traps */

	ptrace(PTRACE_CONT, child_pid, NULL, 0);

	check_success("Test int 3 trap");



	ptrace(PTRACE_CONT, child_pid, NULL, 0);

}



int main(int argc, char **argv)

{

	pid_t pid;

	int ret;



	pid = fork();

	if (!pid) {

		trigger_tests();

		return 0;

	}



	child_pid = pid;



	wait(NULL);



	launch_tests();



	wait(NULL);



	return 0;

}

tools/testing/selftests/run_tests

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#!/bin/bash



TARGETS=

TARGETS=breakpoints



for TARGET in $TARGETS

do

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