/*-
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kdb.h>
#include <sys/proc.h>
#include <sys/reg.h>

#include <machine/cpu.h>
#include <machine/frame.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/stack.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>

#include <ddb/ddb.h>
#include <ddb/db_access.h>
#include <ddb/db_sym.h>
#include <ddb/db_variables.h>

static db_varfcn_t db_esp;
static db_varfcn_t db_frame;
static db_varfcn_t db_frame_seg;
static db_varfcn_t db_gs;
static db_varfcn_t db_ss;

/*
 * Machine register set.
 */
#define DB_OFFSET(x)    (db_expr_t *)offsetof(struct trapframe, x)
struct db_variable db_regs[] = {
        { "cs",         DB_OFFSET(tf_cs),       db_frame_seg },
        { "ds",         DB_OFFSET(tf_ds),       db_frame_seg },
        { "es",         DB_OFFSET(tf_es),       db_frame_seg },
        { "fs",         DB_OFFSET(tf_fs),       db_frame_seg },
        { "gs",         NULL,                   db_gs },
        { "ss",         NULL,                   db_ss },
        { "eax",        DB_OFFSET(tf_eax),      db_frame },
        { "ecx",        DB_OFFSET(tf_ecx),      db_frame },
        { "edx",        DB_OFFSET(tf_edx),      db_frame },
        { "ebx",        DB_OFFSET(tf_ebx),      db_frame },
        { "esp",        NULL,                   db_esp },
        { "ebp",        DB_OFFSET(tf_ebp),      db_frame },
        { "esi",        DB_OFFSET(tf_esi),      db_frame },
        { "edi",        DB_OFFSET(tf_edi),      db_frame },
        { "eip",        DB_OFFSET(tf_eip),      db_frame },
        { "efl",        DB_OFFSET(tf_eflags),   db_frame },
};
struct db_variable *db_eregs = db_regs + nitems(db_regs);

static __inline int
get_esp(struct trapframe *tf)
{
        return (TF_HAS_STACKREGS(tf) ? tf->tf_esp : (intptr_t)&tf->tf_esp);
}

static int
db_frame(struct db_variable *vp, db_expr_t *valuep, int op)
{
        int *reg;

        if (kdb_frame == NULL)
                return (0);

        reg = (int *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep);
        if (op == DB_VAR_GET)
                *valuep = *reg;
        else
                *reg = *valuep;
        return (1);
}

static int
db_frame_seg(struct db_variable *vp, db_expr_t *valuep, int op)
{
        struct trapframe_vm86 *tfp;
        int off;
        uint16_t *reg;

        if (kdb_frame == NULL)
                return (0);

        off = (intptr_t)vp->valuep;
        if (kdb_frame->tf_eflags & PSL_VM) {
                tfp = (void *)kdb_frame;
                switch ((intptr_t)vp->valuep) {
                case (intptr_t)DB_OFFSET(tf_cs):
                        reg = (uint16_t *)&tfp->tf_cs;
                        break;
                case (intptr_t)DB_OFFSET(tf_ds):
                        reg = (uint16_t *)&tfp->tf_vm86_ds;
                        break;
                case (intptr_t)DB_OFFSET(tf_es):
                        reg = (uint16_t *)&tfp->tf_vm86_es;
                        break;
                case (intptr_t)DB_OFFSET(tf_fs):
                        reg = (uint16_t *)&tfp->tf_vm86_fs;
                        break;
                }
        } else
                reg = (uint16_t *)((uintptr_t)kdb_frame + off);
        if (op == DB_VAR_GET)
                *valuep = *reg;
        else
                *reg = *valuep;
        return (1);
}

static int
db_esp(struct db_variable *vp, db_expr_t *valuep, int op)
{

        if (kdb_frame == NULL)
                return (0);

        if (op == DB_VAR_GET)
                *valuep = get_esp(kdb_frame);
        else if (TF_HAS_STACKREGS(kdb_frame))
                kdb_frame->tf_esp = *valuep;
        return (1);
}

static int
db_gs(struct db_variable *vp, db_expr_t *valuep, int op)
{
        struct trapframe_vm86 *tfp;

        if (kdb_frame != NULL && kdb_frame->tf_eflags & PSL_VM) {
                tfp = (void *)kdb_frame;
                if (op == DB_VAR_GET)
                        *valuep = tfp->tf_vm86_gs;
                else
                        tfp->tf_vm86_gs = *valuep;
                return (1);
        }
        if (op == DB_VAR_GET)
                *valuep = rgs();
        else
                load_gs(*valuep);
        return (1);
}

static int
db_ss(struct db_variable *vp, db_expr_t *valuep, int op)
{

        if (kdb_frame == NULL)
                return (0);

        if (op == DB_VAR_GET)
                *valuep = TF_HAS_STACKREGS(kdb_frame) ? kdb_frame->tf_ss :
                    rss();
        else if (TF_HAS_STACKREGS(kdb_frame))
                kdb_frame->tf_ss = *valuep;
        return (1);
}

#define NORMAL          0
#define TRAP            1
#define INTERRUPT       2
#define SYSCALL         3
#define DOUBLE_FAULT    4

static void db_nextframe(struct i386_frame **, db_addr_t *, struct thread *);
static int db_numargs(struct i386_frame *);
static void db_print_stack_entry(const char *, int, char **, int *, db_addr_t,
    void *);

/*
 * Figure out how many arguments were passed into the frame at "fp".
 */
static int
db_numargs(struct i386_frame *fp)
{
        char   *argp;
        int     inst;
        int     args;

        argp = (char *)db_get_value((int)&fp->f_retaddr, 4, false);
        /*
         * XXX etext is wrong for LKMs.  We should attempt to interpret
         * the instruction at the return address in all cases.  This
         * may require better fault handling.
         */
        if (argp < btext || argp >= etext) {
                args = -1;
        } else {
retry:
                inst = db_get_value((int)argp, 4, false);
                if ((inst & 0xff) == 0x59)      /* popl %ecx */
                        args = 1;
                else if ((inst & 0xffff) == 0xc483)     /* addl $Ibs, %esp */
                        args = ((inst >> 16) & 0xff) / 4;
                else if ((inst & 0xf8ff) == 0xc089) {   /* movl %eax, %Reg */
                        argp += 2;
                        goto retry;
                } else
                        args = -1;
        }
        return (args);
}

static void
db_print_stack_entry(const char *name, int narg, char **argnp, int *argp,
    db_addr_t callpc, void *frame)
{
        int n = narg >= 0 ? narg : 5;

        db_printf("%s(", name);
        while (n) {
                if (argnp)
                        db_printf("%s=", *argnp++);
                db_printf("%r", db_get_value((int)argp, 4, false));
                argp++;
                if (--n != 0)
                        db_printf(",");
        }
        if (narg < 0)
                db_printf(",...");
        db_printf(") at ");
        db_printsym(callpc, DB_STGY_PROC);
        if (frame != NULL)
                db_printf("/frame 0x%r", (register_t)frame);
        db_printf("\n");
}

/*
 * Figure out the next frame up in the call stack.
 */
static void
db_nextframe(struct i386_frame **fp, db_addr_t *ip, struct thread *td)
{
        struct trapframe *tf;
        int frame_type;
        int eip, esp, ebp;
        db_expr_t offset;
        c_db_sym_t sym;
        const char *name;

        eip = db_get_value((int) &(*fp)->f_retaddr, 4, false);
        ebp = db_get_value((int) &(*fp)->f_frame, 4, false);

        /*
         * Figure out frame type.  We look at the address just before
         * the saved instruction pointer as the saved EIP is after the
         * call function, and if the function being called is marked as
         * dead (such as panic() at the end of dblfault_handler()), then
         * the instruction at the saved EIP will be part of a different
         * function (syscall() in this example) rather than the one that
         * actually made the call.
         */
        frame_type = NORMAL;

        if (eip >= PMAP_TRM_MIN_ADDRESS) {
                sym = db_search_symbol(eip - 1 - setidt_disp, DB_STGY_ANY,
                    &offset);
        } else {
                sym = db_search_symbol(eip - 1, DB_STGY_ANY, &offset);
        }
        db_symbol_values(sym, &name, NULL);
        if (name != NULL) {
                if (strcmp(name, "calltrap") == 0 ||
                    strcmp(name, "fork_trampoline") == 0)
                        frame_type = TRAP;
                else if (strncmp(name, "Xatpic_intr", 11) == 0 ||
                    strncmp(name, "Xapic_isr", 9) == 0) {
                        frame_type = INTERRUPT;
                } else if (strcmp(name, "Xlcall_syscall") == 0 ||
                    strcmp(name, "Xint0x80_syscall") == 0)
                        frame_type = SYSCALL;
                else if (strcmp(name, "dblfault_handler") == 0)
                        frame_type = DOUBLE_FAULT;
                else if (strcmp(name, "Xtimerint") == 0 ||
                    strcmp(name, "Xxen_intr_upcall") == 0)
                        frame_type = INTERRUPT;
                else if (strcmp(name, "Xcpustop") == 0 ||
                    strcmp(name, "Xrendezvous") == 0 ||
                    strcmp(name, "Xipi_intr_bitmap_handler") == 0) {
                        /* No arguments. */
                        frame_type = INTERRUPT;
                }
        }

        /*
         * Normal frames need no special processing.
         */
        if (frame_type == NORMAL) {
                *ip = (db_addr_t) eip;
                *fp = (struct i386_frame *) ebp;
                return;
        }

        db_print_stack_entry(name, 0, 0, 0, eip, &(*fp)->f_frame);

        /*
         * For a double fault, we have to snag the values from the
         * previous TSS since a double fault uses a task gate to
         * switch to a known good state.
         */
        if (frame_type == DOUBLE_FAULT) {
                esp = PCPU_GET(common_tssp)->tss_esp;
                eip = PCPU_GET(common_tssp)->tss_eip;
                ebp = PCPU_GET(common_tssp)->tss_ebp;
                db_printf(
                    "--- trap 0x17, eip = %#r, esp = %#r, ebp = %#r ---\n",
                    eip, esp, ebp);
                *ip = (db_addr_t) eip;
                *fp = (struct i386_frame *) ebp;
                return;
        }

        /*
         * Point to base of trapframe which is just above the current
         * frame.  Pointer to it was put into %ebp by the kernel entry
         * code.
         */
        tf = (struct trapframe *)(*fp)->f_frame;

        /*
         * This can be the case for e.g. fork_trampoline, last frame
         * of a kernel thread stack.
         */
        if (tf == NULL) {
                *ip = 0;
                *fp = 0;
                db_printf("--- kthread start\n");
                return;
        }

        esp = get_esp(tf);
        eip = tf->tf_eip;
        ebp = tf->tf_ebp;
        switch (frame_type) {
        case TRAP:
                db_printf("--- trap %#r", tf->tf_trapno);
                break;
        case SYSCALL:
                db_printf("--- syscall");
                db_decode_syscall(td, tf->tf_eax);
                break;
        case INTERRUPT:
                db_printf("--- interrupt");
                break;
        default:
                panic("The moon has moved again.");
        }
        db_printf(", eip = %#r, esp = %#r, ebp = %#r ---\n", eip, esp, ebp);

        /*
         * Detect the last (trap) frame on the kernel stack, where we
         * entered kernel from usermode.  Terminate tracing in this
         * case.
         */
        switch (frame_type) {
        case TRAP:
        case INTERRUPT:
                if (!TRAPF_USERMODE(tf))
                        break;
                /* FALLTHROUGH */
        case SYSCALL:
                ebp = 0;
                eip = 0;
                break;
        }

        *ip = (db_addr_t) eip;
        *fp = (struct i386_frame *) ebp;
}

static int
db_backtrace(struct thread *td, struct trapframe *tf, struct i386_frame *frame,
    db_addr_t pc, register_t sp, int count)
{
        struct i386_frame *actframe;
#define MAXNARG 16
        char *argnames[MAXNARG], **argnp = NULL;
        const char *name;
        int *argp;
        db_expr_t offset;
        c_db_sym_t sym;
        int instr, narg;
        bool first;

        if (db_segsize(tf) == 16) {
                db_printf(
"--- 16-bit%s, cs:eip = %#x:%#x, ss:esp = %#x:%#x, ebp = %#x, tf = %p ---\n",
                    (tf->tf_eflags & PSL_VM) ? " (vm86)" : "",
                    tf->tf_cs, tf->tf_eip,
                    TF_HAS_STACKREGS(tf) ? tf->tf_ss : rss(),
                    TF_HAS_STACKREGS(tf) ? tf->tf_esp : (intptr_t)&tf->tf_esp,
                    tf->tf_ebp, tf);
                return (0);
        }

        /* 'frame' can be null initially.  Just print the pc then. */
        if (frame == NULL)
                goto out;

        /*
         * If an indirect call via an invalid pointer caused a trap,
         * %pc contains the invalid address while the return address
         * of the unlucky caller has been saved by CPU on the stack
         * just before the trap frame.  In this case, try to recover
         * the caller's address so that the first frame is assigned
         * to the right spot in the right function, for that is where
         * the failure actually happened.
         *
         * This trick depends on the fault address stashed in tf_err
         * by trap_fatal() before entering KDB.
         */
        if (kdb_frame && pc == kdb_frame->tf_err) {
                /*
                 * Find where the trap frame actually ends.
                 * It won't contain tf_esp or tf_ss unless crossing rings.
                 */
                if (TF_HAS_STACKREGS(kdb_frame))
                        instr = (int)(kdb_frame + 1);
                else
                        instr = (int)&kdb_frame->tf_esp;
                pc = db_get_value(instr, 4, false);
        }

        if (count == -1)
                count = 1024;

        first = true;
        while (count-- && !db_pager_quit) {
                sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
                db_symbol_values(sym, &name, NULL);

                /*
                 * Attempt to determine a (possibly fake) frame that gives
                 * the caller's pc.  It may differ from `frame' if the
                 * current function never sets up a standard frame or hasn't
                 * set one up yet or has just discarded one.  The last two
                 * cases can be guessed fairly reliably for code generated
                 * by gcc.  The first case is too much trouble to handle in
                 * general because the amount of junk on the stack depends
                 * on the pc (the special handling of "calltrap", etc. in
                 * db_nextframe() works because the `next' pc is special).
                 */
                actframe = frame;
                if (first) {
                        first = false;
                        if (sym == C_DB_SYM_NULL && sp != 0) {
                                /*
                                 * If a symbol couldn't be found, we've probably
                                 * jumped to a bogus location, so try and use
                                 * the return address to find our caller.
                                 */
                                db_print_stack_entry(name, 0, 0, 0, pc,
                                    NULL);
                                pc = db_get_value(sp, 4, false);
                                if (db_search_symbol(pc, DB_STGY_PROC,
                                    &offset) == C_DB_SYM_NULL)
                                        break;
                                continue;
                        } else if (tf != NULL) {
                                instr = db_get_value(pc, 4, false);
                                if ((instr & 0xffffff) == 0x00e58955) {
                                        /* pushl %ebp; movl %esp, %ebp */
                                        actframe = (void *)(get_esp(tf) - 4);
                                } else if ((instr & 0xffff) == 0x0000e589) {
                                        /* movl %esp, %ebp */
                                        actframe = (void *)get_esp(tf);
                                        if (tf->tf_ebp == 0) {
                                                /* Fake frame better. */
                                                frame = actframe;
                                        }
                                } else if ((instr & 0xff) == 0x000000c3) {
                                        /* ret */
                                        actframe = (void *)(get_esp(tf) - 4);
                                } else if (offset == 0) {
                                        /* Probably an assembler symbol. */
                                        actframe = (void *)(get_esp(tf) - 4);
                                }
                        } else if (strcmp(name, "fork_trampoline") == 0) {
                                /*
                                 * Don't try to walk back on a stack for a
                                 * process that hasn't actually been run yet.
                                 */
                                db_print_stack_entry(name, 0, 0, 0, pc,
                                    actframe);
                                break;
                        }
                }

                argp = &actframe->f_arg0;
                narg = MAXNARG;
                if (sym != NULL && db_sym_numargs(sym, &narg, argnames)) {
                        argnp = argnames;
                } else {
                        narg = db_numargs(frame);
                }

                db_print_stack_entry(name, narg, argnp, argp, pc, actframe);

                if (actframe != frame) {
                        /* `frame' belongs to caller. */
                        pc = (db_addr_t)
                            db_get_value((int)&actframe->f_retaddr, 4, false);
                        continue;
                }

                db_nextframe(&frame, &pc, td);

out:
                /*
                 * 'frame' can be null here, either because it was initially
                 * null or because db_nextframe() found no frame.
                 * db_nextframe() may also have found a non-kernel frame.
                 * !INKERNEL() classifies both.  Stop tracing if either,
                 * after printing the pc if it is the kernel.
                 */
                if (frame == NULL || frame <= actframe) {
                        if (pc != 0) {
                                sym = db_search_symbol(pc, DB_STGY_ANY,
                                    &offset);
                                db_symbol_values(sym, &name, NULL);
                                db_print_stack_entry(name, 0, 0, 0, pc, frame);
                        }
                        break;
                }
        }

        return (0);
}

void
db_trace_self(void)
{
        struct i386_frame *frame;
        db_addr_t callpc;
        register_t ebp;

        __asm __volatile("movl %%ebp,%0" : "=r" (ebp));
        frame = (struct i386_frame *)ebp;
        callpc = (db_addr_t)db_get_value((int)&frame->f_retaddr, 4, false);
        frame = frame->f_frame;
        db_backtrace(curthread, NULL, frame, callpc, 0, -1);
}

int
db_trace_thread(struct thread *thr, int count)
{
        struct pcb *ctx;
        struct trapframe *tf;

        ctx = kdb_thr_ctx(thr);
        tf = thr == kdb_thread ? kdb_frame : NULL;
        return (db_backtrace(thr, tf, (struct i386_frame *)ctx->pcb_ebp,
            ctx->pcb_eip, ctx->pcb_esp, count));
}

void
db_md_list_watchpoints(void)
{

        dbreg_list_watchpoints();
}