// SPDX-License-Identifier: GPL-2.0
/*
 * Kernel Debugger Architecture Independent Support Functions
 *
 * Copyright (c) 1999-2004 Silicon Graphics, Inc.  All Rights Reserved.
 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
 * 03/02/13    added new 2.5 kallsyms <xavier.bru@bull.net>
 */

#include <linux/types.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kallsyms.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/ptrace.h>
#include <linux/highmem.h>
#include <linux/hardirq.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <linux/kdb.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include "kdb_private.h"

/*
 * kdbgetsymval - Return the address of the given symbol.
 *
 * Parameters:
 *      symname Character string containing symbol name
 *      symtab  Structure to receive results
 * Returns:
 *      0       Symbol not found, symtab zero filled
 *      1       Symbol mapped to module/symbol/section, data in symtab
 */
int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
{
        kdb_dbg_printf(AR, "symname=%s, symtab=%px\n", symname, symtab);
        memset(symtab, 0, sizeof(*symtab));
        symtab->sym_start = kallsyms_lookup_name(symname);
        if (symtab->sym_start) {
                kdb_dbg_printf(AR, "returns 1, symtab->sym_start=0x%lx\n",
                               symtab->sym_start);
                return 1;
        }
        kdb_dbg_printf(AR, "returns 0\n");
        return 0;
}
EXPORT_SYMBOL(kdbgetsymval);

/**
 * kdbnearsym() - Return the name of the symbol with the nearest address
 *                less than @addr.
 * @addr: Address to check for near symbol
 * @symtab: Structure to receive results
 *
 * WARNING: This function may return a pointer to a single statically
 * allocated buffer (namebuf). kdb's unusual calling context (single
 * threaded, all other CPUs halted) provides us sufficient locking for
 * this to be safe. The only constraint imposed by the static buffer is
 * that the caller must consume any previous reply prior to another call
 * to lookup a new symbol.
 *
 * Note that, strictly speaking, some architectures may re-enter the kdb
 * trap if the system turns out to be very badly damaged and this breaks
 * the single-threaded assumption above. In these circumstances successful
 * continuation and exit from the inner trap is unlikely to work and any
 * user attempting this receives a prominent warning before being allowed
 * to progress. In these circumstances we remain memory safe because
 * namebuf[KSYM_NAME_LEN-1] will never change from '\0' although we do
 * tolerate the possibility of garbled symbol display from the outer kdb
 * trap.
 *
 * Return:
 * * 0 - No sections contain this address, symtab zero filled
 * * 1 - Address mapped to module/symbol/section, data in symtab
 */
int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
{
        int ret = 0;
        unsigned long symbolsize = 0;
        unsigned long offset = 0;
        static char namebuf[KSYM_NAME_LEN];

        kdb_dbg_printf(AR, "addr=0x%lx, symtab=%px\n", addr, symtab);
        memset(symtab, 0, sizeof(*symtab));

        if (addr < 4096)
                goto out;

        symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
                                (char **)(&symtab->mod_name), namebuf);
        if (offset > 8*1024*1024) {
                symtab->sym_name = NULL;
                addr = offset = symbolsize = 0;
        }
        symtab->sym_start = addr - offset;
        symtab->sym_end = symtab->sym_start + symbolsize;
        ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';

        if (symtab->mod_name == NULL)
                symtab->mod_name = "kernel";
        kdb_dbg_printf(AR, "returns %d symtab->sym_start=0x%lx, symtab->mod_name=%px, symtab->sym_name=%px (%s)\n",
                       ret, symtab->sym_start, symtab->mod_name, symtab->sym_name, symtab->sym_name);
out:
        return ret;
}

static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];

/*
 * kallsyms_symbol_complete
 *
 * Parameters:
 *      prefix_name     prefix of a symbol name to lookup
 *      max_len         maximum length that can be returned
 * Returns:
 *      Number of symbols which match the given prefix.
 * Notes:
 *      prefix_name is changed to contain the longest unique prefix that
 *      starts with this prefix (tab completion).
 */
int kallsyms_symbol_complete(char *prefix_name, int max_len)
{
        loff_t pos = 0;
        int prefix_len = strlen(prefix_name), prev_len = 0;
        int i, number = 0;
        const char *name;

        while ((name = kdb_walk_kallsyms(&pos))) {
                if (strncmp(name, prefix_name, prefix_len) == 0) {
                        strscpy(ks_namebuf, name, sizeof(ks_namebuf));
                        /* Work out the longest name that matches the prefix */
                        if (++number == 1) {
                                prev_len = min_t(int, max_len-1,
                                                 strlen(ks_namebuf));
                                memcpy(ks_namebuf_prev, ks_namebuf, prev_len);
                                ks_namebuf_prev[prev_len] = '\0';
                                continue;
                        }
                        for (i = 0; i < prev_len; i++) {
                                if (ks_namebuf[i] != ks_namebuf_prev[i]) {
                                        prev_len = i;
                                        ks_namebuf_prev[i] = '\0';
                                        break;
                                }
                        }
                }
        }
        if (prev_len > prefix_len)
                memcpy(prefix_name, ks_namebuf_prev, prev_len+1);
        return number;
}

/*
 * kallsyms_symbol_next
 *
 * Parameters:
 *      prefix_name     prefix of a symbol name to lookup
 *      flag    0 means search from the head, 1 means continue search.
 *      buf_size        maximum length that can be written to prefix_name
 *                      buffer
 * Returns:
 *      1 if a symbol matches the given prefix.
 *      0 if no string found
 */
int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size)
{
        int prefix_len = strlen(prefix_name);
        static loff_t pos;
        const char *name;

        if (!flag)
                pos = 0;

        while ((name = kdb_walk_kallsyms(&pos))) {
                if (!strncmp(name, prefix_name, prefix_len))
                        return strscpy(prefix_name, name, buf_size);
        }
        return 0;
}

/*
 * kdb_symbol_print - Standard method for printing a symbol name and offset.
 * Inputs:
 *      addr    Address to be printed.
 *      symtab  Address of symbol data, if NULL this routine does its
 *              own lookup.
 *      punc    Punctuation for string, bit field.
 * Remarks:
 *      The string and its punctuation is only printed if the address
 *      is inside the kernel, except that the value is always printed
 *      when requested.
 */
void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
                      unsigned int punc)
{
        kdb_symtab_t symtab, *symtab_p2;
        if (symtab_p) {
                symtab_p2 = (kdb_symtab_t *)symtab_p;
        } else {
                symtab_p2 = &symtab;
                kdbnearsym(addr, symtab_p2);
        }
        if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
                return;
        if (punc & KDB_SP_SPACEB)
                kdb_printf(" ");
        if (punc & KDB_SP_VALUE)
                kdb_printf(kdb_machreg_fmt0, addr);
        if (symtab_p2->sym_name) {
                if (punc & KDB_SP_VALUE)
                        kdb_printf(" ");
                if (punc & KDB_SP_PAREN)
                        kdb_printf("(");
                if (strcmp(symtab_p2->mod_name, "kernel"))
                        kdb_printf("[%s]", symtab_p2->mod_name);
                kdb_printf("%s", symtab_p2->sym_name);
                if (addr != symtab_p2->sym_start)
                        kdb_printf("+0x%lx", addr - symtab_p2->sym_start);
                if (punc & KDB_SP_SYMSIZE)
                        kdb_printf("/0x%lx",
                                   symtab_p2->sym_end - symtab_p2->sym_start);
                if (punc & KDB_SP_PAREN)
                        kdb_printf(")");
        }
        if (punc & KDB_SP_SPACEA)
                kdb_printf(" ");
        if (punc & KDB_SP_NEWLINE)
                kdb_printf("\n");
}

/*
 * kdb_strdup - kdb equivalent of strdup, for disasm code.
 * Inputs:
 *      str     The string to duplicate.
 *      type    Flags to kmalloc for the new string.
 * Returns:
 *      Address of the new string, NULL if storage could not be allocated.
 * Remarks:
 *      This is not in lib/string.c because it uses kmalloc which is not
 *      available when string.o is used in boot loaders.
 */
char *kdb_strdup(const char *str, gfp_t type)
{
        size_t n = strlen(str) + 1;
        char *s = kmalloc(n, type);
        if (!s)
                return NULL;
        memcpy(s, str, n);
        return s;
}

/*
 * kdb_strdup_dequote - same as kdb_strdup(), but trims surrounding quotes from
 *                      the input string if present.
 * Remarks:
 *      Quotes are only removed if there is both a leading and a trailing quote.
 */
char *kdb_strdup_dequote(const char *str, gfp_t type)
{
        size_t len = strlen(str);
        char *s;

        if (str[0] == '"' && len > 1 && str[len - 1] == '"') {
                /* trim both leading and trailing quotes */
                str++;
                len -= 2;
        }

        len++; /* add space for NUL terminator */

        s = kmalloc(len, type);
        if (!s)
                return NULL;

        memcpy(s, str, len - 1);
        s[len - 1] = '\0';

        return s;
}

/*
 * kdb_getarea_size - Read an area of data.  The kdb equivalent of
 *      copy_from_user, with kdb messages for invalid addresses.
 * Inputs:
 *      res     Pointer to the area to receive the result.
 *      addr    Address of the area to copy.
 *      size    Size of the area.
 * Returns:
 *      0 for success, < 0 for error.
 */
int kdb_getarea_size(void *res, unsigned long addr, size_t size)
{
        int ret = copy_from_kernel_nofault((char *)res, (char *)addr, size);
        if (ret) {
                if (!KDB_STATE(SUPPRESS)) {
                        kdb_func_printf("Bad address 0x%lx\n", addr);
                        KDB_STATE_SET(SUPPRESS);
                }
                ret = KDB_BADADDR;
        } else {
                KDB_STATE_CLEAR(SUPPRESS);
        }
        return ret;
}

/*
 * kdb_putarea_size - Write an area of data.  The kdb equivalent of
 *      copy_to_user, with kdb messages for invalid addresses.
 * Inputs:
 *      addr    Address of the area to write to.
 *      res     Pointer to the area holding the data.
 *      size    Size of the area.
 * Returns:
 *      0 for success, < 0 for error.
 */
int kdb_putarea_size(unsigned long addr, void *res, size_t size)
{
        int ret = copy_to_kernel_nofault((char *)addr, (char *)res, size);
        if (ret) {
                if (!KDB_STATE(SUPPRESS)) {
                        kdb_func_printf("Bad address 0x%lx\n", addr);
                        KDB_STATE_SET(SUPPRESS);
                }
                ret = KDB_BADADDR;
        } else {
                KDB_STATE_CLEAR(SUPPRESS);
        }
        return ret;
}

/*
 * kdb_getphys - Read data from a physical address. Validate the
 *      address is in range, use kmap_local_page() to get data
 *      similar to kdb_getarea() - but for phys addresses
 * Inputs:
 *      res     Pointer to the word to receive the result
 *      addr    Physical address of the area to copy
 *      size    Size of the area
 * Returns:
 *      0 for success, < 0 for error.
 */
static int kdb_getphys(void *res, unsigned long addr, size_t size)
{
        unsigned long pfn;
        void *vaddr;
        struct page *page;

        pfn = (addr >> PAGE_SHIFT);
        if (!pfn_valid(pfn))
                return 1;
        page = pfn_to_page(pfn);
        vaddr = kmap_local_page(page);
        memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
        kunmap_local(vaddr);

        return 0;
}

/*
 * kdb_getphysword
 * Inputs:
 *      word    Pointer to the word to receive the result.
 *      addr    Address of the area to copy.
 *      size    Size of the area.
 * Returns:
 *      0 for success, < 0 for error.
 */
int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
{
        int diag;
        __u8  w1;
        __u16 w2;
        __u32 w4;
        __u64 w8;
        *word = 0;      /* Default value if addr or size is invalid */

        switch (size) {
        case 1:
                diag = kdb_getphys(&w1, addr, sizeof(w1));
                if (!diag)
                        *word = w1;
                break;
        case 2:
                diag = kdb_getphys(&w2, addr, sizeof(w2));
                if (!diag)
                        *word = w2;
                break;
        case 4:
                diag = kdb_getphys(&w4, addr, sizeof(w4));
                if (!diag)
                        *word = w4;
                break;
        case 8:
                if (size <= sizeof(*word)) {
                        diag = kdb_getphys(&w8, addr, sizeof(w8));
                        if (!diag)
                                *word = w8;
                        break;
                }
                fallthrough;
        default:
                diag = KDB_BADWIDTH;
                kdb_func_printf("bad width %zu\n", size);
        }
        return diag;
}

/*
 * kdb_getword - Read a binary value.  Unlike kdb_getarea, this treats
 *      data as numbers.
 * Inputs:
 *      word    Pointer to the word to receive the result.
 *      addr    Address of the area to copy.
 *      size    Size of the area.
 * Returns:
 *      0 for success, < 0 for error.
 */
int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
{
        int diag;
        __u8  w1;
        __u16 w2;
        __u32 w4;
        __u64 w8;
        *word = 0;      /* Default value if addr or size is invalid */
        switch (size) {
        case 1:
                diag = kdb_getarea(w1, addr);
                if (!diag)
                        *word = w1;
                break;
        case 2:
                diag = kdb_getarea(w2, addr);
                if (!diag)
                        *word = w2;
                break;
        case 4:
                diag = kdb_getarea(w4, addr);
                if (!diag)
                        *word = w4;
                break;
        case 8:
                if (size <= sizeof(*word)) {
                        diag = kdb_getarea(w8, addr);
                        if (!diag)
                                *word = w8;
                        break;
                }
                fallthrough;
        default:
                diag = KDB_BADWIDTH;
                kdb_func_printf("bad width %zu\n", size);
        }
        return diag;
}

/*
 * kdb_putword - Write a binary value.  Unlike kdb_putarea, this
 *      treats data as numbers.
 * Inputs:
 *      addr    Address of the area to write to..
 *      word    The value to set.
 *      size    Size of the area.
 * Returns:
 *      0 for success, < 0 for error.
 */
int kdb_putword(unsigned long addr, unsigned long word, size_t size)
{
        int diag;
        __u8  w1;
        __u16 w2;
        __u32 w4;
        __u64 w8;
        switch (size) {
        case 1:
                w1 = word;
                diag = kdb_putarea(addr, w1);
                break;
        case 2:
                w2 = word;
                diag = kdb_putarea(addr, w2);
                break;
        case 4:
                w4 = word;
                diag = kdb_putarea(addr, w4);
                break;
        case 8:
                if (size <= sizeof(word)) {
                        w8 = word;
                        diag = kdb_putarea(addr, w8);
                        break;
                }
                fallthrough;
        default:
                diag = KDB_BADWIDTH;
                kdb_func_printf("bad width %zu\n", size);
        }
        return diag;
}



/*
 * kdb_task_state_char - Return the character that represents the task state.
 * Inputs:
 *      p       struct task for the process
 * Returns:
 *      One character to represent the task state.
 */
char kdb_task_state_char (const struct task_struct *p)
{
        unsigned long tmp;
        char state;
        int cpu;

        if (!p ||
            copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
                return 'E';

        state = task_state_to_char((struct task_struct *) p);

        if (is_idle_task(p)) {
                /* Idle task.  Is it really idle, apart from the kdb
                 * interrupt? */
                cpu = kdb_process_cpu(p);
                if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
                        if (cpu != kdb_initial_cpu)
                                state = '-';    /* idle task */
                }
        } else if (!p->mm && strchr("IMS", state)) {
                state = tolower(state);         /* sleeping system daemon */
        }
        return state;
}

/*
 * kdb_task_state - Return true if a process has the desired state
 *      given by the mask.
 * Inputs:
 *      p       struct task for the process
 *      mask    set of characters used to select processes; both NULL
 *              and the empty string mean adopt a default filter, which
 *              is to suppress sleeping system daemons and the idle tasks
 * Returns:
 *      True if the process matches at least one criteria defined by the mask.
 */
bool kdb_task_state(const struct task_struct *p, const char *mask)
{
        char state = kdb_task_state_char(p);

        /* If there is no mask, then we will filter code that runs when the
         * scheduler is idling and any system daemons that are currently
         * sleeping.
         */
        if (!mask || mask[0] == '\0')
                return !strchr("-ims", state);

        /* A is a special case that matches all states */
        if (strchr(mask, 'A'))
                return true;

        return strchr(mask, state);
}