// SPDX-License-Identifier: GPL-2.0
/*
 * Kernel Debugger Architecture Independent Breakpoint Handler
 *
 * Copyright (c) 1999-2004 Silicon Graphics, Inc.  All Rights Reserved.
 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
 */

#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/kdb.h>
#include <linux/kgdb.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include "kdb_private.h"

/*
 * Table of kdb_breakpoints
 */
kdb_bp_t kdb_breakpoints[KDB_MAXBPT];

static void kdb_setsinglestep(struct pt_regs *regs)
{
        KDB_STATE_SET(DOING_SS);
}

static char *kdb_rwtypes[] = {
        "Instruction(i)",
        "Instruction(Register)",
        "Data Write",
        "I/O",
        "Data Access"
};

static char *kdb_bptype(kdb_bp_t *bp)
{
        if (bp->bp_type < 0 || bp->bp_type > 4)
                return "";

        return kdb_rwtypes[bp->bp_type];
}

static int kdb_parsebp(int argc, const char **argv, int *nextargp, kdb_bp_t *bp)
{
        int nextarg = *nextargp;
        int diag;

        bp->bph_length = 1;
        if ((argc + 1) != nextarg) {
                if (strncasecmp(argv[nextarg], "datar", sizeof("datar")) == 0)
                        bp->bp_type = BP_ACCESS_WATCHPOINT;
                else if (strncasecmp(argv[nextarg], "dataw", sizeof("dataw")) == 0)
                        bp->bp_type = BP_WRITE_WATCHPOINT;
                else if (strncasecmp(argv[nextarg], "inst", sizeof("inst")) == 0)
                        bp->bp_type = BP_HARDWARE_BREAKPOINT;
                else
                        return KDB_ARGCOUNT;

                bp->bph_length = 1;

                nextarg++;

                if ((argc + 1) != nextarg) {
                        unsigned long len;

                        diag = kdbgetularg((char *)argv[nextarg],
                                           &len);
                        if (diag)
                                return diag;


                        if (len > 8)
                                return KDB_BADLENGTH;

                        bp->bph_length = len;
                        nextarg++;
                }

                if ((argc + 1) != nextarg)
                        return KDB_ARGCOUNT;
        }

        *nextargp = nextarg;
        return 0;
}

static int _kdb_bp_remove(kdb_bp_t *bp)
{
        int ret = 1;
        if (!bp->bp_installed)
                return ret;
        if (!bp->bp_type)
                ret = dbg_remove_sw_break(bp->bp_addr);
        else
                ret = arch_kgdb_ops.remove_hw_breakpoint(bp->bp_addr,
                         bp->bph_length,
                         bp->bp_type);
        if (ret == 0)
                bp->bp_installed = 0;
        return ret;
}

static void kdb_handle_bp(struct pt_regs *regs, kdb_bp_t *bp)
{
        if (KDB_DEBUG(BP))
                kdb_printf("regs->ip = 0x%lx\n", instruction_pointer(regs));

        /*
         * Setup single step
         */
        kdb_setsinglestep(regs);

        /*
         * Reset delay attribute
         */
        bp->bp_delay = 0;
        bp->bp_delayed = 1;
}

static int _kdb_bp_install(struct pt_regs *regs, kdb_bp_t *bp)
{
        int ret;
        /*
         * Install the breakpoint, if it is not already installed.
         */

        if (KDB_DEBUG(BP))
                kdb_printf("%s: bp_installed %d\n",
                           __func__, bp->bp_installed);
        if (!KDB_STATE(SSBPT))
                bp->bp_delay = 0;
        if (bp->bp_installed)
                return 1;
        if (bp->bp_delay || (bp->bp_delayed && KDB_STATE(DOING_SS))) {
                if (KDB_DEBUG(BP))
                        kdb_printf("%s: delayed bp\n", __func__);
                kdb_handle_bp(regs, bp);
                return 0;
        }
        if (!bp->bp_type)
                ret = dbg_set_sw_break(bp->bp_addr);
        else
                ret = arch_kgdb_ops.set_hw_breakpoint(bp->bp_addr,
                         bp->bph_length,
                         bp->bp_type);
        if (ret == 0) {
                bp->bp_installed = 1;
        } else {
                kdb_printf("%s: failed to set breakpoint at 0x%lx\n",
                           __func__, bp->bp_addr);
                if (!bp->bp_type) {
                        kdb_printf("Software breakpoints are unavailable.\n"
                                   "  Boot the kernel with rodata=off\n"
                                   "  OR use hw breaks: help bph\n");
                }
                return 1;
        }
        return 0;
}

/*
 * kdb_bp_install
 *
 *      Install kdb_breakpoints prior to returning from the
 *      kernel debugger.  This allows the kdb_breakpoints to be set
 *      upon functions that are used internally by kdb, such as
 *      printk().  This function is only called once per kdb session.
 */
void kdb_bp_install(struct pt_regs *regs)
{
        int i;

        for (i = 0; i < KDB_MAXBPT; i++) {
                kdb_bp_t *bp = &kdb_breakpoints[i];

                if (KDB_DEBUG(BP)) {
                        kdb_printf("%s: bp %d bp_enabled %d\n",
                                   __func__, i, bp->bp_enabled);
                }
                if (bp->bp_enabled)
                        _kdb_bp_install(regs, bp);
        }
}

/*
 * kdb_bp_remove
 *
 *      Remove kdb_breakpoints upon entry to the kernel debugger.
 *
 * Parameters:
 *      None.
 * Outputs:
 *      None.
 * Returns:
 *      None.
 * Locking:
 *      None.
 * Remarks:
 */
void kdb_bp_remove(void)
{
        int i;

        for (i = KDB_MAXBPT - 1; i >= 0; i--) {
                kdb_bp_t *bp = &kdb_breakpoints[i];

                if (KDB_DEBUG(BP)) {
                        kdb_printf("%s: bp %d bp_enabled %d\n",
                                   __func__, i, bp->bp_enabled);
                }
                if (bp->bp_enabled)
                        _kdb_bp_remove(bp);
        }
}


/*
 * kdb_printbp
 *
 *      Internal function to format and print a breakpoint entry.
 *
 * Parameters:
 *      None.
 * Outputs:
 *      None.
 * Returns:
 *      None.
 * Locking:
 *      None.
 * Remarks:
 */

static void kdb_printbp(kdb_bp_t *bp, int i)
{
        kdb_printf("%s ", kdb_bptype(bp));
        kdb_printf("BP #%d at ", i);
        kdb_symbol_print(bp->bp_addr, NULL, KDB_SP_DEFAULT);

        if (bp->bp_enabled)
                kdb_printf("\n    is enabled ");
        else
                kdb_printf("\n    is disabled");

        kdb_printf("  addr at %016lx, hardtype=%d installed=%d\n",
                   bp->bp_addr, bp->bp_type, bp->bp_installed);

        kdb_printf("\n");
}

/*
 * kdb_bp
 *
 *      Handle the bp commands.
 *
 *      [bp|bph] <addr-expression> [DATAR|DATAW]
 *
 * Parameters:
 *      argc    Count of arguments in argv
 *      argv    Space delimited command line arguments
 * Outputs:
 *      None.
 * Returns:
 *      Zero for success, a kdb diagnostic if failure.
 * Locking:
 *      None.
 * Remarks:
 *
 *      bp      Set breakpoint on all cpus.  Only use hardware assist if need.
 *      bph     Set breakpoint on all cpus.  Force hardware register
 */

static int kdb_bp(int argc, const char **argv)
{
        int i, bpno;
        kdb_bp_t *bp, *bp_check;
        int diag;
        char *symname = NULL;
        long offset = 0ul;
        int nextarg;
        kdb_bp_t template = {0};

        if (argc == 0) {
                /*
                 * Display breakpoint table
                 */
                for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT;
                     bpno++, bp++) {
                        if (bp->bp_free)
                                continue;
                        kdb_printbp(bp, bpno);
                }

                return 0;
        }

        nextarg = 1;
        diag = kdbgetaddrarg(argc, argv, &nextarg, &template.bp_addr,
                             &offset, &symname);
        if (diag)
                return diag;
        if (!template.bp_addr)
                return KDB_BADINT;

        /*
         * This check is redundant (since the breakpoint machinery should
         * be doing the same check during kdb_bp_install) but gives the
         * user immediate feedback.
         */
        diag = kgdb_validate_break_address(template.bp_addr);
        if (diag)
                return diag;

        /*
         * Find an empty bp structure to allocate
         */
        for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT; bpno++, bp++) {
                if (bp->bp_free)
                        break;
        }

        if (bpno == KDB_MAXBPT)
                return KDB_TOOMANYBPT;

        if (strcmp(argv[0], "bph") == 0) {
                template.bp_type = BP_HARDWARE_BREAKPOINT;
                diag = kdb_parsebp(argc, argv, &nextarg, &template);
                if (diag)
                        return diag;
        } else {
                template.bp_type = BP_BREAKPOINT;
        }

        /*
         * Check for clashing breakpoints.
         *
         * Note, in this design we can't have hardware breakpoints
         * enabled for both read and write on the same address.
         */
        for (i = 0, bp_check = kdb_breakpoints; i < KDB_MAXBPT;
             i++, bp_check++) {
                if (!bp_check->bp_free &&
                    bp_check->bp_addr == template.bp_addr) {
                        kdb_printf("You already have a breakpoint at "
                                   kdb_bfd_vma_fmt0 "\n", template.bp_addr);
                        return KDB_DUPBPT;
                }
        }

        template.bp_enabled = 1;

        /*
         * Actually allocate the breakpoint found earlier
         */
        *bp = template;
        bp->bp_free = 0;

        kdb_printbp(bp, bpno);

        return 0;
}

/*
 * kdb_bc
 *
 *      Handles the 'bc', 'be', and 'bd' commands
 *
 *      [bd|bc|be] <breakpoint-number>
 *      [bd|bc|be] *
 *
 * Parameters:
 *      argc    Count of arguments in argv
 *      argv    Space delimited command line arguments
 * Outputs:
 *      None.
 * Returns:
 *      Zero for success, a kdb diagnostic for failure
 * Locking:
 *      None.
 * Remarks:
 */
static int kdb_bc(int argc, const char **argv)
{
        unsigned long addr;
        kdb_bp_t *bp = NULL;
        int lowbp = KDB_MAXBPT;
        int highbp = 0;
        int done = 0;
        int i;
        int diag = 0;

        int cmd;                        /* KDBCMD_B? */
#define KDBCMD_BC       0
#define KDBCMD_BE       1
#define KDBCMD_BD       2

        if (strcmp(argv[0], "be") == 0)
                cmd = KDBCMD_BE;
        else if (strcmp(argv[0], "bd") == 0)
                cmd = KDBCMD_BD;
        else
                cmd = KDBCMD_BC;

        if (argc != 1)
                return KDB_ARGCOUNT;

        if (strcmp(argv[1], "*") == 0) {
                lowbp = 0;
                highbp = KDB_MAXBPT;
        } else {
                diag = kdbgetularg(argv[1], &addr);
                if (diag)
                        return diag;

                /*
                 * For addresses less than the maximum breakpoint number,
                 * assume that the breakpoint number is desired.
                 */
                if (addr < KDB_MAXBPT) {
                        lowbp = highbp = addr;
                        highbp++;
                } else {
                        for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT;
                            i++, bp++) {
                                if (bp->bp_addr == addr) {
                                        lowbp = highbp = i;
                                        highbp++;
                                        break;
                                }
                        }
                }
        }

        /*
         * Now operate on the set of breakpoints matching the input
         * criteria (either '*' for all, or an individual breakpoint).
         */
        for (bp = &kdb_breakpoints[lowbp], i = lowbp;
            i < highbp;
            i++, bp++) {
                if (bp->bp_free)
                        continue;

                done++;

                switch (cmd) {
                case KDBCMD_BC:
                        bp->bp_enabled = 0;

                        kdb_printf("Breakpoint %d at "
                                   kdb_bfd_vma_fmt " cleared\n",
                                   i, bp->bp_addr);

                        bp->bp_addr = 0;
                        bp->bp_free = 1;

                        break;
                case KDBCMD_BE:
                        if (bp->bp_enabled)
                                break;

                        bp->bp_enabled = 1;

                        kdb_printf("Breakpoint %d at "
                                   kdb_bfd_vma_fmt " enabled\n",
                                   i, bp->bp_addr);

                        break;
                case KDBCMD_BD:
                        if (!bp->bp_enabled)
                                break;

                        bp->bp_enabled = 0;

                        kdb_printf("Breakpoint %d at "
                                   kdb_bfd_vma_fmt " disabled\n",
                                   i, bp->bp_addr);

                        break;
                }
                if (bp->bp_delay && (cmd == KDBCMD_BC || cmd == KDBCMD_BD)) {
                        bp->bp_delay = 0;
                        KDB_STATE_CLEAR(SSBPT);
                }
        }

        return (!done) ? KDB_BPTNOTFOUND : 0;
}

/*
 * kdb_ss
 *
 *      Process the 'ss' (Single Step) command.
 *
 *      ss
 *
 * Parameters:
 *      argc    Argument count
 *      argv    Argument vector
 * Outputs:
 *      None.
 * Returns:
 *      KDB_CMD_SS for success, a kdb error if failure.
 * Locking:
 *      None.
 * Remarks:
 *
 *      Set the arch specific option to trigger a debug trap after the next
 *      instruction.
 */

static int kdb_ss(int argc, const char **argv)
{
        if (argc != 0)
                return KDB_ARGCOUNT;
        /*
         * Set trace flag and go.
         */
        KDB_STATE_SET(DOING_SS);
        return KDB_CMD_SS;
}

static kdbtab_t bptab[] = {
        {       .name = "bp",
                .func = kdb_bp,
                .usage = "[<vaddr>]",
                .help = "Set/Display breakpoints",
                .flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
        },
        {       .name = "bl",
                .func = kdb_bp,
                .usage = "[<vaddr>]",
                .help = "Display breakpoints",
                .flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
        },
        {       .name = "bc",
                .func = kdb_bc,
                .usage = "<bpnum>",
                .help = "Clear Breakpoint",
                .flags = KDB_ENABLE_FLOW_CTRL,
        },
        {       .name = "be",
                .func = kdb_bc,
                .usage = "<bpnum>",
                .help = "Enable Breakpoint",
                .flags = KDB_ENABLE_FLOW_CTRL,
        },
        {       .name = "bd",
                .func = kdb_bc,
                .usage = "<bpnum>",
                .help = "Disable Breakpoint",
                .flags = KDB_ENABLE_FLOW_CTRL,
        },
        {       .name = "ss",
                .func = kdb_ss,
                .usage = "",
                .help = "Single Step",
                .minlen = 1,
                .flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
        },
};

static kdbtab_t bphcmd = {
        .name = "bph",
        .func = kdb_bp,
        .usage = "[<vaddr>]",
        .help = "[datar [length]|dataw [length]]   Set hw brk",
        .flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
};

/* Initialize the breakpoint table and register breakpoint commands. */

void __init kdb_initbptab(void)
{
        int i;
        kdb_bp_t *bp;

        /*
         * First time initialization.
         */
        memset(&kdb_breakpoints, '\0', sizeof(kdb_breakpoints));

        for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
                bp->bp_free = 1;

        kdb_register_table(bptab, ARRAY_SIZE(bptab));
        if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
                kdb_register_table(&bphcmd, 1);
}