// SPDX-License-Identifier: GPL-2.0-only
/*
 * kgdbts is a test suite for kgdb for the sole purpose of validating
 * that key pieces of the kgdb internals are working properly such as
 * HW/SW breakpoints, single stepping, and NMI.
 *
 * Created by: Jason Wessel <jason.wessel@windriver.com>
 *
 * Copyright (c) 2008 Wind River Systems, Inc.
 */
/* Information about the kgdb test suite.
 * -------------------------------------
 *
 * The kgdb test suite is designed as a KGDB I/O module which
 * simulates the communications that a debugger would have with kgdb.
 * The tests are broken up in to a line by line and referenced here as
 * a "get" which is kgdb requesting input and "put" which is kgdb
 * sending a response.
 *
 * The kgdb suite can be invoked from the kernel command line
 * arguments system or executed dynamically at run time.  The test
 * suite uses the variable "kgdbts" to obtain the information about
 * which tests to run and to configure the verbosity level.  The
 * following are the various characters you can use with the kgdbts=
 * line:
 *
 * When using the "kgdbts=" you only choose one of the following core
 * test types:
 * A = Run all the core tests silently
 * V1 = Run all the core tests with minimal output
 * V2 = Run all the core tests in debug mode
 *
 * You can also specify optional tests:
 * N## = Go to sleep with interrupts of for ## seconds
 *       to test the HW NMI watchdog
 * F## = Break at kernel_clone for ## iterations
 * S## = Break at sys_open for ## iterations
 * I## = Run the single step test ## iterations
 *
 * NOTE: that the kernel_clone and sys_open tests are mutually exclusive.
 *
 * To invoke the kgdb test suite from boot you use a kernel start
 * argument as follows:
 *      kgdbts=V1 kgdbwait
 * Or if you wanted to perform the NMI test for 6 seconds and kernel_clone
 * test for 100 forks, you could use:
 *      kgdbts=V1N6F100 kgdbwait
 *
 * The test suite can also be invoked at run time with:
 *      echo kgdbts=V1N6F100 > /sys/module/kgdbts/parameters/kgdbts
 * Or as another example:
 *      echo kgdbts=V2 > /sys/module/kgdbts/parameters/kgdbts
 *
 * When developing a new kgdb arch specific implementation or
 * using these tests for the purpose of regression testing,
 * several invocations are required.
 *
 * 1) Boot with the test suite enabled by using the kernel arguments
 *       "kgdbts=V1F100 kgdbwait"
 *    ## If kgdb arch specific implementation has NMI use
 *       "kgdbts=V1N6F100
 *
 * 2) After the system boot run the basic test.
 * echo kgdbts=V1 > /sys/module/kgdbts/parameters/kgdbts
 *
 * 3) Run the concurrency tests.  It is best to use n+1
 *    while loops where n is the number of cpus you have
 *    in your system.  The example below uses only two
 *    loops.
 *
 * ## This tests break points on sys_open
 * while [ 1 ] ; do find / > /dev/null 2>&1 ; done &
 * while [ 1 ] ; do find / > /dev/null 2>&1 ; done &
 * echo kgdbts=V1S10000 > /sys/module/kgdbts/parameters/kgdbts
 * fg # and hit control-c
 * fg # and hit control-c
 * ## This tests break points on kernel_clone
 * while [ 1 ] ; do date > /dev/null ; done &
 * while [ 1 ] ; do date > /dev/null ; done &
 * echo kgdbts=V1F1000 > /sys/module/kgdbts/parameters/kgdbts
 * fg # and hit control-c
 *
 */

#include <linux/kernel.h>
#include <linux/kgdb.h>
#include <linux/ctype.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/nmi.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/sched/task.h>
#include <linux/kallsyms.h>

#include <asm/sections.h>

#define v1printk(a...) do {             \
        if (verbose)                    \
                printk(KERN_INFO a);    \
} while (0)
#define v2printk(a...) do {             \
        if (verbose > 1) {              \
                printk(KERN_INFO a);    \
        }                               \
        touch_nmi_watchdog();           \
} while (0)
#define eprintk(a...) do {              \
        printk(KERN_ERR a);             \
        WARN_ON(1);                     \
} while (0)
#define MAX_CONFIG_LEN          40

static struct kgdb_io kgdbts_io_ops;
static char get_buf[BUFMAX];
static int get_buf_cnt;
static char put_buf[BUFMAX];
static int put_buf_cnt;
static char scratch_buf[BUFMAX];
static int verbose;
static int repeat_test;
static int test_complete;
static int send_ack;
static int final_ack;
static int force_hwbrks;
static int hwbreaks_ok;
static int hw_break_val;
static int hw_break_val2;
static int cont_instead_of_sstep;
static unsigned long cont_thread_id;
static unsigned long sstep_thread_id;
#if defined(CONFIG_ARM) || defined(CONFIG_MIPS) || defined(CONFIG_SPARC)
static int arch_needs_sstep_emulation = 1;
#else
static int arch_needs_sstep_emulation;
#endif
static unsigned long cont_addr;
static unsigned long sstep_addr;
static int restart_from_top_after_write;
static int sstep_state;

/* Storage for the registers, in GDB format. */
static unsigned long kgdbts_gdb_regs[(NUMREGBYTES +
                                        sizeof(unsigned long) - 1) /
                                        sizeof(unsigned long)];
static struct pt_regs kgdbts_regs;

/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
static int configured           = -1;

#ifdef CONFIG_KGDB_TESTS_BOOT_STRING
static char config[MAX_CONFIG_LEN] = CONFIG_KGDB_TESTS_BOOT_STRING;
#else
static char config[MAX_CONFIG_LEN];
#endif
static struct kparam_string kps = {
        .string                 = config,
        .maxlen                 = MAX_CONFIG_LEN,
};

static void fill_get_buf(char *buf);

struct test_struct {
        char *get;
        char *put;
        void (*get_handler)(char *);
        int (*put_handler)(char *, char *);
};

struct test_state {
        char *name;
        struct test_struct *tst;
        int idx;
        int (*run_test) (int, int);
        int (*validate_put) (char *);
};

static struct test_state ts;

static int kgdbts_unreg_thread(void *ptr)
{
        /* Wait until the tests are complete and then ungresiter the I/O
         * driver.
         */
        while (!final_ack)
                msleep_interruptible(1500);
        /* Pause for any other threads to exit after final ack. */
        msleep_interruptible(1000);
        if (configured)
                kgdb_unregister_io_module(&kgdbts_io_ops);
        configured = 0;

        return 0;
}

/* This is noinline such that it can be used for a single location to
 * place a breakpoint
 */
static noinline void kgdbts_break_test(void)
{
        v2printk("kgdbts: breakpoint complete\n");
}

/*
 * This is a cached wrapper for kallsyms_lookup_name().
 *
 * The cache is a big win for several tests. For example it more the doubles
 * the cycles per second during the sys_open test. This is not theoretic,
 * the performance improvement shows up at human scale, especially when
 * testing using emulators.
 *
 * Obviously neither re-entrant nor thread-safe but that is OK since it
 * can only be called from the debug trap (and therefore all other CPUs
 * are halted).
 */
static unsigned long lookup_addr(char *arg)
{
        static char cached_arg[KSYM_NAME_LEN];
        static unsigned long cached_addr;

        if (strcmp(arg, cached_arg)) {
                strscpy(cached_arg, arg, KSYM_NAME_LEN);
                cached_addr = kallsyms_lookup_name(arg);
        }

        return (unsigned long)dereference_function_descriptor(
                        (void *)cached_addr);
}

static void break_helper(char *bp_type, char *arg, unsigned long vaddr)
{
        unsigned long addr;

        if (arg)
                addr = lookup_addr(arg);
        else
                addr = vaddr;

        sprintf(scratch_buf, "%s,%lx,%i", bp_type, addr,
                BREAK_INSTR_SIZE);
        fill_get_buf(scratch_buf);
}

static void sw_break(char *arg)
{
        break_helper(force_hwbrks ? "Z1" : "Z0", arg, 0);
}

static void sw_rem_break(char *arg)
{
        break_helper(force_hwbrks ? "z1" : "z0", arg, 0);
}

static void hw_break(char *arg)
{
        break_helper("Z1", arg, 0);
}

static void hw_rem_break(char *arg)
{
        break_helper("z1", arg, 0);
}

static void hw_write_break(char *arg)
{
        break_helper("Z2", arg, 0);
}

static void hw_rem_write_break(char *arg)
{
        break_helper("z2", arg, 0);
}

static void hw_access_break(char *arg)
{
        break_helper("Z4", arg, 0);
}

static void hw_rem_access_break(char *arg)
{
        break_helper("z4", arg, 0);
}

static void hw_break_val_access(void)
{
        hw_break_val2 = hw_break_val;
}

static void hw_break_val_write(void)
{
        hw_break_val++;
}

static int get_thread_id_continue(char *put_str, char *arg)
{
        char *ptr = &put_str[11];

        if (put_str[1] != 'T' || put_str[2] != '0')
                return 1;
        kgdb_hex2long(&ptr, &cont_thread_id);
        return 0;
}

static int check_and_rewind_pc(char *put_str, char *arg)
{
        unsigned long addr = lookup_addr(arg);
        unsigned long ip;
        int offset = 0;

        kgdb_hex2mem(&put_str[1], (char *)kgdbts_gdb_regs,
                 NUMREGBYTES);
        gdb_regs_to_pt_regs(kgdbts_gdb_regs, &kgdbts_regs);
        ip = instruction_pointer(&kgdbts_regs);
        v2printk("Stopped at IP: %lx\n", ip);
#ifdef GDB_ADJUSTS_BREAK_OFFSET
        /* On some arches, a breakpoint stop requires it to be decremented */
        if (addr + BREAK_INSTR_SIZE == ip)
                offset = -BREAK_INSTR_SIZE;
#endif

        if (arch_needs_sstep_emulation && sstep_addr &&
            ip + offset == sstep_addr &&
            ((!strcmp(arg, "do_sys_openat2") || !strcmp(arg, "kernel_clone")))) {
                /* This is special case for emulated single step */
                v2printk("Emul: rewind hit single step bp\n");
                restart_from_top_after_write = 1;
        } else if (strcmp(arg, "silent") && ip + offset != addr) {
                eprintk("kgdbts: BP mismatch %lx expected %lx\n",
                           ip + offset, addr);
                return 1;
        }
        /* Readjust the instruction pointer if needed */
        ip += offset;
        cont_addr = ip;
#ifdef GDB_ADJUSTS_BREAK_OFFSET
        instruction_pointer_set(&kgdbts_regs, ip);
#endif
        return 0;
}

static int check_single_step(char *put_str, char *arg)
{
        unsigned long addr = lookup_addr(arg);
        static int matched_id;

        /*
         * From an arch indepent point of view the instruction pointer
         * should be on a different instruction
         */
        kgdb_hex2mem(&put_str[1], (char *)kgdbts_gdb_regs,
                 NUMREGBYTES);
        gdb_regs_to_pt_regs(kgdbts_gdb_regs, &kgdbts_regs);
        v2printk("Singlestep stopped at IP: %lx\n",
                   instruction_pointer(&kgdbts_regs));

        if (sstep_thread_id != cont_thread_id) {
                /*
                 * Ensure we stopped in the same thread id as before, else the
                 * debugger should continue until the original thread that was
                 * single stepped is scheduled again, emulating gdb's behavior.
                 */
                v2printk("ThrID does not match: %lx\n", cont_thread_id);
                if (arch_needs_sstep_emulation) {
                        if (matched_id &&
                            instruction_pointer(&kgdbts_regs) != addr)
                                goto continue_test;
                        matched_id++;
                        ts.idx -= 2;
                        sstep_state = 0;
                        return 0;
                }
                cont_instead_of_sstep = 1;
                ts.idx -= 4;
                return 0;
        }
continue_test:
        matched_id = 0;
        if (instruction_pointer(&kgdbts_regs) == addr) {
                eprintk("kgdbts: SingleStep failed at %lx\n",
                           instruction_pointer(&kgdbts_regs));
                return 1;
        }

        return 0;
}

static void write_regs(char *arg)
{
        memset(scratch_buf, 0, sizeof(scratch_buf));
        scratch_buf[0] = 'G';
        pt_regs_to_gdb_regs(kgdbts_gdb_regs, &kgdbts_regs);
        kgdb_mem2hex((char *)kgdbts_gdb_regs, &scratch_buf[1], NUMREGBYTES);
        fill_get_buf(scratch_buf);
}

static void skip_back_repeat_test(char *arg)
{
        int go_back = simple_strtol(arg, NULL, 10);

        repeat_test--;
        if (repeat_test <= 0) {
                ts.idx++;
        } else {
                if (repeat_test % 100 == 0)
                        v1printk("kgdbts:RUN ... %d remaining\n", repeat_test);

                ts.idx -= go_back;
        }
        fill_get_buf(ts.tst[ts.idx].get);
}

static int got_break(char *put_str, char *arg)
{
        test_complete = 1;
        if (!strncmp(put_str+1, arg, 2)) {
                if (!strncmp(arg, "T0", 2))
                        test_complete = 2;
                return 0;
        }
        return 1;
}

static void get_cont_catch(char *arg)
{
        /* Always send detach because the test is completed at this point */
        fill_get_buf("D");
}

static int put_cont_catch(char *put_str, char *arg)
{
        /* This is at the end of the test and we catch any and all input */
        v2printk("kgdbts: cleanup task: %lx\n", sstep_thread_id);
        ts.idx--;
        return 0;
}

static int emul_reset(char *put_str, char *arg)
{
        if (strncmp(put_str, "$OK", 3))
                return 1;
        if (restart_from_top_after_write) {
                restart_from_top_after_write = 0;
                ts.idx = -1;
        }
        return 0;
}

static void emul_sstep_get(char *arg)
{
        if (!arch_needs_sstep_emulation) {
                if (cont_instead_of_sstep) {
                        cont_instead_of_sstep = 0;
                        fill_get_buf("c");
                } else {
                        fill_get_buf(arg);
                }
                return;
        }
        switch (sstep_state) {
        case 0:
                v2printk("Emulate single step\n");
                /* Start by looking at the current PC */
                fill_get_buf("g");
                break;
        case 1:
                /* set breakpoint */
                break_helper("Z0", NULL, sstep_addr);
                break;
        case 2:
                /* Continue */
                fill_get_buf("c");
                break;
        case 3:
                /* Clear breakpoint */
                break_helper("z0", NULL, sstep_addr);
                break;
        default:
                eprintk("kgdbts: ERROR failed sstep get emulation\n");
        }
        sstep_state++;
}

static int emul_sstep_put(char *put_str, char *arg)
{
        if (!arch_needs_sstep_emulation) {
                char *ptr = &put_str[11];
                if (put_str[1] != 'T' || put_str[2] != '0')
                        return 1;
                kgdb_hex2long(&ptr, &sstep_thread_id);
                return 0;
        }
        switch (sstep_state) {
        case 1:
                /* validate the "g" packet to get the IP */
                kgdb_hex2mem(&put_str[1], (char *)kgdbts_gdb_regs,
                         NUMREGBYTES);
                gdb_regs_to_pt_regs(kgdbts_gdb_regs, &kgdbts_regs);
                v2printk("Stopped at IP: %lx\n",
                         instruction_pointer(&kgdbts_regs));
                /* Want to stop at IP + break instruction size by default */
                sstep_addr = cont_addr + BREAK_INSTR_SIZE;
                break;
        case 2:
                if (strncmp(put_str, "$OK", 3)) {
                        eprintk("kgdbts: failed sstep break set\n");
                        return 1;
                }
                break;
        case 3:
                if (strncmp(put_str, "$T0", 3)) {
                        eprintk("kgdbts: failed continue sstep\n");
                        return 1;
                } else {
                        char *ptr = &put_str[11];
                        kgdb_hex2long(&ptr, &sstep_thread_id);
                }
                break;
        case 4:
                if (strncmp(put_str, "$OK", 3)) {
                        eprintk("kgdbts: failed sstep break unset\n");
                        return 1;
                }
                /* Single step is complete so continue on! */
                sstep_state = 0;
                return 0;
        default:
                eprintk("kgdbts: ERROR failed sstep put emulation\n");
        }

        /* Continue on the same test line until emulation is complete */
        ts.idx--;
        return 0;
}

static int final_ack_set(char *put_str, char *arg)
{
        if (strncmp(put_str+1, arg, 2))
                return 1;
        final_ack = 1;
        return 0;
}
/*
 * Test to plant a breakpoint and detach, which should clear out the
 * breakpoint and restore the original instruction.
 */
static struct test_struct plant_and_detach_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "kgdbts_break_test", "OK", sw_break, }, /* set sw breakpoint */
        { "D", "OK" }, /* Detach */
        { "", "" },
};

/*
 * Simple test to write in a software breakpoint, check for the
 * correct stop location and detach.
 */
static struct test_struct sw_breakpoint_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "kgdbts_break_test", "OK", sw_break, }, /* set sw breakpoint */
        { "c", "T0*", }, /* Continue */
        { "g", "kgdbts_break_test", NULL, check_and_rewind_pc },
        { "write", "OK", write_regs },
        { "kgdbts_break_test", "OK", sw_rem_break }, /*remove breakpoint */
        { "D", "OK" }, /* Detach */
        { "D", "OK", NULL,  got_break }, /* On success we made it here */
        { "", "" },
};

/*
 * Test a known bad memory read location to test the fault handler and
 * read bytes 1-8 at the bad address
 */
static struct test_struct bad_read_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "m0,1", "E*" }, /* read 1 byte at address 1 */
        { "m0,2", "E*" }, /* read 1 byte at address 2 */
        { "m0,3", "E*" }, /* read 1 byte at address 3 */
        { "m0,4", "E*" }, /* read 1 byte at address 4 */
        { "m0,5", "E*" }, /* read 1 byte at address 5 */
        { "m0,6", "E*" }, /* read 1 byte at address 6 */
        { "m0,7", "E*" }, /* read 1 byte at address 7 */
        { "m0,8", "E*" }, /* read 1 byte at address 8 */
        { "D", "OK" }, /* Detach which removes all breakpoints and continues */
        { "", "" },
};

/*
 * Test for hitting a breakpoint, remove it, single step, plant it
 * again and detach.
 */
static struct test_struct singlestep_break_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "kgdbts_break_test", "OK", sw_break, }, /* set sw breakpoint */
        { "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
        { "kgdbts_break_test", "OK", sw_rem_break }, /*remove breakpoint */
        { "g", "kgdbts_break_test", NULL, check_and_rewind_pc },
        { "write", "OK", write_regs }, /* Write registers */
        { "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
        { "g", "kgdbts_break_test", NULL, check_single_step },
        { "kgdbts_break_test", "OK", sw_break, }, /* set sw breakpoint */
        { "c", "T0*", }, /* Continue */
        { "g", "kgdbts_break_test", NULL, check_and_rewind_pc },
        { "write", "OK", write_regs }, /* Write registers */
        { "D", "OK" }, /* Remove all breakpoints and continues */
        { "", "" },
};

/*
 * Test for hitting a breakpoint at kernel_clone for what ever the number
 * of iterations required by the variable repeat_test.
 */
static struct test_struct do_kernel_clone_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "kernel_clone", "OK", sw_break, }, /* set sw breakpoint */
        { "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
        { "kernel_clone", "OK", sw_rem_break }, /*remove breakpoint */
        { "g", "kernel_clone", NULL, check_and_rewind_pc }, /* check location */
        { "write", "OK", write_regs, emul_reset }, /* Write registers */
        { "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
        { "g", "kernel_clone", NULL, check_single_step },
        { "kernel_clone", "OK", sw_break, }, /* set sw breakpoint */
        { "7", "T0*", skip_back_repeat_test }, /* Loop based on repeat_test */
        { "D", "OK", NULL, final_ack_set }, /* detach and unregister I/O */
        { "", "", get_cont_catch, put_cont_catch },
};

/* Test for hitting a breakpoint at sys_open for what ever the number
 * of iterations required by the variable repeat_test.
 */
static struct test_struct sys_open_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "do_sys_openat2", "OK", sw_break, }, /* set sw breakpoint */
        { "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
        { "do_sys_openat2", "OK", sw_rem_break }, /*remove breakpoint */
        { "g", "do_sys_openat2", NULL, check_and_rewind_pc }, /* check location */
        { "write", "OK", write_regs, emul_reset }, /* Write registers */
        { "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
        { "g", "do_sys_openat2", NULL, check_single_step },
        { "do_sys_openat2", "OK", sw_break, }, /* set sw breakpoint */
        { "7", "T0*", skip_back_repeat_test }, /* Loop based on repeat_test */
        { "D", "OK", NULL, final_ack_set }, /* detach and unregister I/O */
        { "", "", get_cont_catch, put_cont_catch },
};

/*
 * Test for hitting a simple hw breakpoint
 */
static struct test_struct hw_breakpoint_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "kgdbts_break_test", "OK", hw_break, }, /* set hw breakpoint */
        { "c", "T0*", }, /* Continue */
        { "g", "kgdbts_break_test", NULL, check_and_rewind_pc },
        { "write", "OK", write_regs },
        { "kgdbts_break_test", "OK", hw_rem_break }, /*remove breakpoint */
        { "D", "OK" }, /* Detach */
        { "D", "OK", NULL,  got_break }, /* On success we made it here */
        { "", "" },
};

/*
 * Test for hitting a hw write breakpoint
 */
static struct test_struct hw_write_break_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "hw_break_val", "OK", hw_write_break, }, /* set hw breakpoint */
        { "c", "T0*", NULL, got_break }, /* Continue */
        { "g", "silent", NULL, check_and_rewind_pc },
        { "write", "OK", write_regs },
        { "hw_break_val", "OK", hw_rem_write_break }, /*remove breakpoint */
        { "D", "OK" }, /* Detach */
        { "D", "OK", NULL,  got_break }, /* On success we made it here */
        { "", "" },
};

/*
 * Test for hitting a hw access breakpoint
 */
static struct test_struct hw_access_break_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "hw_break_val", "OK", hw_access_break, }, /* set hw breakpoint */
        { "c", "T0*", NULL, got_break }, /* Continue */
        { "g", "silent", NULL, check_and_rewind_pc },
        { "write", "OK", write_regs },
        { "hw_break_val", "OK", hw_rem_access_break }, /*remove breakpoint */
        { "D", "OK" }, /* Detach */
        { "D", "OK", NULL,  got_break }, /* On success we made it here */
        { "", "" },
};

/*
 * Test for hitting a hw access breakpoint
 */
static struct test_struct nmi_sleep_test[] = {
        { "?", "S0*" }, /* Clear break points */
        { "c", "T0*", NULL, got_break }, /* Continue */
        { "D", "OK" }, /* Detach */
        { "D", "OK", NULL,  got_break }, /* On success we made it here */
        { "", "" },
};

static void fill_get_buf(char *buf)
{
        unsigned char checksum = 0;
        int count = 0;
        char ch;

        strcpy(get_buf, "$");
        strcat(get_buf, buf);
        while ((ch = buf[count])) {
                checksum += ch;
                count++;
        }
        strcat(get_buf, "#");
        get_buf[count + 2] = hex_asc_hi(checksum);
        get_buf[count + 3] = hex_asc_lo(checksum);
        get_buf[count + 4] = '\0';
        v2printk("get%i: %s\n", ts.idx, get_buf);
}

static int validate_simple_test(char *put_str)
{
        char *chk_str;

        if (ts.tst[ts.idx].put_handler)
                return ts.tst[ts.idx].put_handler(put_str,
                        ts.tst[ts.idx].put);

        chk_str = ts.tst[ts.idx].put;
        if (*put_str == '$')
                put_str++;

        while (*chk_str != '\0' && *put_str != '\0') {
                /* If someone does a * to match the rest of the string, allow
                 * it, or stop if the received string is complete.
                 */
                if (*put_str == '#' || *chk_str == '*')
                        return 0;
                if (*put_str != *chk_str)
                        return 1;

                chk_str++;
                put_str++;
        }
        if (*chk_str == '\0' && (*put_str == '\0' || *put_str == '#'))
                return 0;

        return 1;
}

static int run_simple_test(int is_get_char, int chr)
{
        int ret = 0;
        if (is_get_char) {
                /* Send an ACK on the get if a prior put completed and set the
                 * send ack variable
                 */
                if (send_ack) {
                        send_ack = 0;
                        return '+';
                }
                /* On the first get char, fill the transmit buffer and then
                 * take from the get_string.
                 */
                if (get_buf_cnt == 0) {
                        if (ts.tst[ts.idx].get_handler)
                                ts.tst[ts.idx].get_handler(ts.tst[ts.idx].get);
                        else
                                fill_get_buf(ts.tst[ts.idx].get);
                }

                if (get_buf[get_buf_cnt] == '\0') {
                        eprintk("kgdbts: ERROR GET: EOB on '%s' at %i\n",
                           ts.name, ts.idx);
                        get_buf_cnt = 0;
                        fill_get_buf("D");
                }
                ret = get_buf[get_buf_cnt];
                get_buf_cnt++;
                return ret;
        }

        /* This callback is a put char which is when kgdb sends data to
         * this I/O module.
         */
        if (ts.tst[ts.idx].get[0] == '\0' && ts.tst[ts.idx].put[0] == '\0' &&
            !ts.tst[ts.idx].get_handler) {
                eprintk("kgdbts: ERROR: beyond end of test on"
                           " '%s' line %i\n", ts.name, ts.idx);
                return 0;
        }

        if (put_buf_cnt >= BUFMAX) {
                eprintk("kgdbts: ERROR: put buffer overflow on"
                           " '%s' line %i\n", ts.name, ts.idx);
                put_buf_cnt = 0;
                return 0;
        }
        /* Ignore everything until the first valid packet start '$' */
        if (put_buf_cnt == 0 && chr != '$')
                return 0;

        put_buf[put_buf_cnt] = chr;
        put_buf_cnt++;

        /* End of packet == #XX so look for the '#' */
        if (put_buf_cnt > 3 && put_buf[put_buf_cnt - 3] == '#') {
                if (put_buf_cnt >= BUFMAX) {
                        eprintk("kgdbts: ERROR: put buffer overflow on"
                                " '%s' line %i\n", ts.name, ts.idx);
                        put_buf_cnt = 0;
                        return 0;
                }
                put_buf[put_buf_cnt] = '\0';
                v2printk("put%i: %s\n", ts.idx, put_buf);
                /* Trigger check here */
                if (ts.validate_put && ts.validate_put(put_buf)) {
                        eprintk("kgdbts: ERROR PUT: end of test "
                           "buffer on '%s' line %i expected %s got %s\n",
                           ts.name, ts.idx, ts.tst[ts.idx].put, put_buf);
                }
                ts.idx++;
                put_buf_cnt = 0;
                get_buf_cnt = 0;
                send_ack = 1;
        }
        return 0;
}

static void init_simple_test(void)
{
        memset(&ts, 0, sizeof(ts));
        ts.run_test = run_simple_test;
        ts.validate_put = validate_simple_test;
}

static void run_plant_and_detach_test(int is_early)
{
        char before[BREAK_INSTR_SIZE];
        char after[BREAK_INSTR_SIZE];

        copy_from_kernel_nofault(before, (char *)kgdbts_break_test,
          BREAK_INSTR_SIZE);
        init_simple_test();
        ts.tst = plant_and_detach_test;
        ts.name = "plant_and_detach_test";
        /* Activate test with initial breakpoint */
        if (!is_early)
                kgdb_breakpoint();
        copy_from_kernel_nofault(after, (char *)kgdbts_break_test,
                        BREAK_INSTR_SIZE);
        if (memcmp(before, after, BREAK_INSTR_SIZE)) {
                printk(KERN_CRIT "kgdbts: ERROR kgdb corrupted memory\n");
                panic("kgdb memory corruption");
        }

        /* complete the detach test */
        if (!is_early)
                kgdbts_break_test();
}

static void run_breakpoint_test(int is_hw_breakpoint)
{
        test_complete = 0;
        init_simple_test();
        if (is_hw_breakpoint) {
                ts.tst = hw_breakpoint_test;
                ts.name = "hw_breakpoint_test";
        } else {
                ts.tst = sw_breakpoint_test;
                ts.name = "sw_breakpoint_test";
        }
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
        /* run code with the break point in it */
        kgdbts_break_test();
        kgdb_breakpoint();

        if (test_complete)
                return;

        eprintk("kgdbts: ERROR %s test failed\n", ts.name);
        if (is_hw_breakpoint)
                hwbreaks_ok = 0;
}

static void run_hw_break_test(int is_write_test)
{
        test_complete = 0;
        init_simple_test();
        if (is_write_test) {
                ts.tst = hw_write_break_test;
                ts.name = "hw_write_break_test";
        } else {
                ts.tst = hw_access_break_test;
                ts.name = "hw_access_break_test";
        }
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
        hw_break_val_access();
        if (is_write_test) {
                if (test_complete == 2) {
                        eprintk("kgdbts: ERROR %s broke on access\n",
                                ts.name);
                        hwbreaks_ok = 0;
                }
                hw_break_val_write();
        }
        kgdb_breakpoint();

        if (test_complete == 1)
                return;

        eprintk("kgdbts: ERROR %s test failed\n", ts.name);
        hwbreaks_ok = 0;
}

static void run_nmi_sleep_test(int nmi_sleep)
{
        unsigned long flags;

        init_simple_test();
        ts.tst = nmi_sleep_test;
        ts.name = "nmi_sleep_test";
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
        local_irq_save(flags);
        mdelay(nmi_sleep*1000);
        touch_nmi_watchdog();
        local_irq_restore(flags);
        if (test_complete != 2)
                eprintk("kgdbts: ERROR nmi_test did not hit nmi\n");
        kgdb_breakpoint();
        if (test_complete == 1)
                return;

        eprintk("kgdbts: ERROR %s test failed\n", ts.name);
}

static void run_bad_read_test(void)
{
        init_simple_test();
        ts.tst = bad_read_test;
        ts.name = "bad_read_test";
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
}

static void run_kernel_clone_test(void)
{
        init_simple_test();
        ts.tst = do_kernel_clone_test;
        ts.name = "do_kernel_clone_test";
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
}

static void run_sys_open_test(void)
{
        init_simple_test();
        ts.tst = sys_open_test;
        ts.name = "sys_open_test";
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
}

static void run_singlestep_break_test(void)
{
        init_simple_test();
        ts.tst = singlestep_break_test;
        ts.name = "singlestep_breakpoint_test";
        /* Activate test with initial breakpoint */
        kgdb_breakpoint();
        kgdbts_break_test();
        kgdbts_break_test();
}

static void kgdbts_run_tests(void)
{
        char *ptr;
        int clone_test = 0;
        int do_sys_open_test = 0;
        int sstep_test = 1000;
        int nmi_sleep = 0;
        int i;

        verbose = 0;
        if (strstr(config, "V1"))
                verbose = 1;
        if (strstr(config, "V2"))
                verbose = 2;

        ptr = strchr(config, 'F');
        if (ptr)
                clone_test = simple_strtol(ptr + 1, NULL, 10);
        ptr = strchr(config, 'S');
        if (ptr)
                do_sys_open_test = simple_strtol(ptr + 1, NULL, 10);
        ptr = strchr(config, 'N');
        if (ptr)

                nmi_sleep = simple_strtol(ptr+1, NULL, 10);
        ptr = strchr(config, 'I');
        if (ptr)
                sstep_test = simple_strtol(ptr+1, NULL, 10);

        /* All HW break point tests */
        if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT) {
                hwbreaks_ok = 1;
                v1printk("kgdbts:RUN hw breakpoint test\n");
                run_breakpoint_test(1);
                v1printk("kgdbts:RUN hw write breakpoint test\n");
                run_hw_break_test(1);
                v1printk("kgdbts:RUN access write breakpoint test\n");
                run_hw_break_test(0);
        }

        /* required internal KGDB tests */
        v1printk("kgdbts:RUN plant and detach test\n");
        run_plant_and_detach_test(0);
        v1printk("kgdbts:RUN sw breakpoint test\n");
        run_breakpoint_test(0);
        v1printk("kgdbts:RUN bad memory access test\n");
        run_bad_read_test();
        v1printk("kgdbts:RUN singlestep test %i iterations\n", sstep_test);
        for (i = 0; i < sstep_test; i++) {
                run_singlestep_break_test();
                if (i % 100 == 0)
                        v1printk("kgdbts:RUN singlestep [%i/%i]\n",
                                 i, sstep_test);
        }

        /* ===Optional tests=== */

        if (nmi_sleep) {
                v1printk("kgdbts:RUN NMI sleep %i seconds test\n", nmi_sleep);
                run_nmi_sleep_test(nmi_sleep);
        }

        /* If the kernel_clone test is run it will be the last test that is
         * executed because a kernel thread will be spawned at the very
         * end to unregister the debug hooks.
         */
        if (clone_test) {
                repeat_test = clone_test;
                printk(KERN_INFO "kgdbts:RUN kernel_clone for %i breakpoints\n",
                        repeat_test);
                kthread_run(kgdbts_unreg_thread, NULL, "kgdbts_unreg");
                run_kernel_clone_test();
                return;
        }

        /* If the sys_open test is run it will be the last test that is
         * executed because a kernel thread will be spawned at the very
         * end to unregister the debug hooks.
         */
        if (do_sys_open_test) {
                repeat_test = do_sys_open_test;
                printk(KERN_INFO "kgdbts:RUN sys_open for %i breakpoints\n",
                        repeat_test);
                kthread_run(kgdbts_unreg_thread, NULL, "kgdbts_unreg");
                run_sys_open_test();
                return;
        }
        /* Shutdown and unregister */
        kgdb_unregister_io_module(&kgdbts_io_ops);
        configured = 0;
}

static int kgdbts_option_setup(char *opt)
{
        if (strlen(opt) >= MAX_CONFIG_LEN) {
                printk(KERN_ERR "kgdbts: config string too long\n");
                return -ENOSPC;
        }
        strcpy(config, opt);
        return 0;
}

__setup("kgdbts=", kgdbts_option_setup);

static int configure_kgdbts(void)
{
        int err = 0;

        if (!strlen(config) || isspace(config[0]))
                goto noconfig;

        final_ack = 0;
        run_plant_and_detach_test(1);

        err = kgdb_register_io_module(&kgdbts_io_ops);
        if (err) {
                configured = 0;
                return err;
        }
        configured = 1;
        kgdbts_run_tests();

        return err;

noconfig:
        config[0] = 0;
        configured = 0;

        return err;
}

static int __init init_kgdbts(void)
{
        /* Already configured? */
        if (configured == 1)
                return 0;

        return configure_kgdbts();
}
device_initcall(init_kgdbts);

static int kgdbts_get_char(void)
{
        int val = 0;

        if (ts.run_test)
                val = ts.run_test(1, 0);

        return val;
}

static void kgdbts_put_char(u8 chr)
{
        if (ts.run_test)
                ts.run_test(0, chr);
}

static int param_set_kgdbts_var(const char *kmessage,
                                const struct kernel_param *kp)
{
        size_t len = strlen(kmessage);

        if (len >= MAX_CONFIG_LEN) {
                printk(KERN_ERR "kgdbts: config string too long\n");
                return -ENOSPC;
        }

        /* Only copy in the string if the init function has not run yet */
        if (configured < 0) {
                strcpy(config, kmessage);
                return 0;
        }

        if (configured == 1) {
                printk(KERN_ERR "kgdbts: ERROR: Already configured and running.\n");
                return -EBUSY;
        }

        strcpy(config, kmessage);
        /* Chop out \n char as a result of echo */
        if (len && config[len - 1] == '\n')
                config[len - 1] = '\0';

        /* Go and configure with the new params. */
        return configure_kgdbts();
}

static void kgdbts_pre_exp_handler(void)
{
        /* Increment the module count when the debugger is active */
        if (!kgdb_connected)
                try_module_get(THIS_MODULE);
}

static void kgdbts_post_exp_handler(void)
{
        /* decrement the module count when the debugger detaches */
        if (!kgdb_connected)
                module_put(THIS_MODULE);
}

static struct kgdb_io kgdbts_io_ops = {
        .name                   = "kgdbts",
        .read_char              = kgdbts_get_char,
        .write_char             = kgdbts_put_char,
        .pre_exception          = kgdbts_pre_exp_handler,
        .post_exception         = kgdbts_post_exp_handler,
};

/*
 * not really modular, but the easiest way to keep compat with existing
 * bootargs behaviour is to continue using module_param here.
 */
module_param_call(kgdbts, param_set_kgdbts_var, param_get_string, &kps, 0644);
MODULE_PARM_DESC(kgdbts, "<A|V1|V2>[F#|S#][N#]");