/*
 * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
 *
 * Rewritten and vastly simplified by Rusty Russell for in-kernel
 * module loader:
 *   Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
 * Stem compression by Andi Kleen.
 */
#include <linux/kallsyms.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/fs.h>
#include <linux/err.h>
#include <linux/proc_fs.h>

/* These will be re-linked against their real values during the second link stage */
extern unsigned long kallsyms_addresses[] __attribute__((weak));
extern unsigned long kallsyms_num_syms __attribute__((weak));
extern char kallsyms_names[] __attribute__((weak));

/* Defined by the linker script. */
extern char _stext[], _etext[], _sinittext[], _einittext[];

static inline int is_kernel_inittext(unsigned long addr)
{
        if (addr >= (unsigned long)_sinittext
            && addr <= (unsigned long)_einittext)
                return 1;
        return 0;
}

static inline int is_kernel_text(unsigned long addr)
{
        if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
                return 1;
        return 0;
}

/* Lookup the address for this symbol. Returns 0 if not found. */
unsigned long kallsyms_lookup_name(const char *name)
{
        char namebuf[KSYM_NAME_LEN+1];
        unsigned long i;
        char *knames;

        for (i = 0, knames = kallsyms_names; i < kallsyms_num_syms; i++) {
                unsigned prefix = *knames++;

                strlcpy(namebuf + prefix, knames, KSYM_NAME_LEN - prefix);
                if (strcmp(namebuf, name) == 0)
                        return kallsyms_addresses[i];

                knames += strlen(knames) + 1;
        }
        return module_kallsyms_lookup_name(name);
}
EXPORT_SYMBOL_GPL(kallsyms_lookup_name);

/*
 * Lookup an address
 * - modname is set to NULL if it's in the kernel
 * - we guarantee that the returned name is valid until we reschedule even if
 *   it resides in a module
 * - we also guarantee that modname will be valid until rescheduled
 */
const char *kallsyms_lookup(unsigned long addr,
                            unsigned long *symbolsize,
                            unsigned long *offset,
                            char **modname, char *namebuf)
{
        unsigned long i, best = 0;
        const char *msym;

        /* This kernel should never had been booted. */
        BUG_ON(!kallsyms_addresses);

        namebuf[KSYM_NAME_LEN] = 0;
        namebuf[0] = 0;

        if (is_kernel_text(addr) || is_kernel_inittext(addr)) {
                unsigned long symbol_end;
                const char *name = kallsyms_names;

                /* They're sorted, we could be clever here, but who cares? */
                for (i = 0; i < kallsyms_num_syms; i++) {
                        if (kallsyms_addresses[i] > kallsyms_addresses[best] &&
                            kallsyms_addresses[i] <= addr)
                                best = i;
                }

                /* Grab name */
                for (i = 0; i <= best; i++) { 
                        unsigned prefix = *name++;
                        strncpy(namebuf + prefix, name, KSYM_NAME_LEN - prefix);
                        name += strlen(name) + 1;
                }

                /* At worst, symbol ends at end of section. */
                if (is_kernel_inittext(addr))
                        symbol_end = (unsigned long)_einittext;
                else
                        symbol_end = (unsigned long)_etext;

                /* Search for next non-aliased symbol */
                for (i = best+1; i < kallsyms_num_syms; i++) {
                        if (kallsyms_addresses[i] > kallsyms_addresses[best]) {
                                symbol_end = kallsyms_addresses[i];
                                break;
                        }
                }

                *symbolsize = symbol_end - kallsyms_addresses[best];
                *modname = NULL;
                *offset = addr - kallsyms_addresses[best];
                return namebuf;
        }

        /* see if it's in a module */
        msym = module_address_lookup(addr, symbolsize, offset, modname);
        if (msym)
                return strncpy(namebuf, msym, KSYM_NAME_LEN);

        return NULL;
}

/* Replace "%s" in format with address, or returns -errno. */
void __print_symbol(const char *fmt, unsigned long address)
{
        char *modname;
        const char *name;
        unsigned long offset, size;
        char namebuf[KSYM_NAME_LEN+1];
        char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN +
                    2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1];

        name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);

        if (!name)
                sprintf(buffer, "0x%lx", address);
        else {
                if (modname)
                        sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
                                size, modname);
                else
                        sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
        }
        printk(fmt, buffer);
}

/* To avoid O(n^2) iteration, we carry prefix along. */
struct kallsym_iter
{
        loff_t pos;
        struct module *owner;
        unsigned long value;
        unsigned int nameoff; /* If iterating in core kernel symbols */
        char type;
        char name[KSYM_NAME_LEN+1];
};

/* Only label it "global" if it is exported. */
static void upcase_if_global(struct kallsym_iter *iter)
{
        if (is_exported(iter->name, iter->owner))
                iter->type += 'A' - 'a';
}

static int get_ksymbol_mod(struct kallsym_iter *iter)
{
        iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
                                         &iter->value,
                                         &iter->type, iter->name);
        if (iter->owner == NULL)
                return 0;

        upcase_if_global(iter);
        return 1;
}

/* Returns space to next name. */
static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
{
        unsigned stemlen, off = iter->nameoff;

        /* First char of each symbol name indicates prefix length
           shared with previous name (stem compression). */
        stemlen = kallsyms_names[off++];

        strlcpy(iter->name+stemlen, kallsyms_names + off,
                KSYM_NAME_LEN+1-stemlen);
        off += strlen(kallsyms_names + off) + 1;
        iter->owner = NULL;
        iter->value = kallsyms_addresses[iter->pos];
        if (is_kernel_text(iter->value) || is_kernel_inittext(iter->value))
                iter->type = 't';
        else
                iter->type = 'd';

        upcase_if_global(iter);
        return off - iter->nameoff;
}

static void reset_iter(struct kallsym_iter *iter)
{
        iter->name[0] = '\0';
        iter->nameoff = 0;
        iter->pos = 0;
}

/* Returns false if pos at or past end of file. */
static int update_iter(struct kallsym_iter *iter, loff_t pos)
{
        /* Module symbols can be accessed randomly. */
        if (pos >= kallsyms_num_syms) {
                iter->pos = pos;
                return get_ksymbol_mod(iter);
        }
        
        /* If we're past the desired position, reset to start. */
        if (pos < iter->pos)
                reset_iter(iter);

        /* We need to iterate through the previous symbols: can be slow */
        for (; iter->pos != pos; iter->pos++) {
                iter->nameoff += get_ksymbol_core(iter);
                cond_resched();
        }
        get_ksymbol_core(iter);
        return 1;
}

static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
        (*pos)++;

        if (!update_iter(m->private, *pos))
                return NULL;
        return p;
}

static void *s_start(struct seq_file *m, loff_t *pos)
{
        if (!update_iter(m->private, *pos))
                return NULL;
        return m->private;
}

static void s_stop(struct seq_file *m, void *p)
{
}

static int s_show(struct seq_file *m, void *p)
{
        struct kallsym_iter *iter = m->private;

        /* Some debugging symbols have no name.  Ignore them. */ 
        if (!iter->name[0])
                return 0;

        if (iter->owner)
                seq_printf(m, "%0*lx %c %s\t[%s]\n",
                           (int)(2*sizeof(void*)),
                           iter->value, iter->type, iter->name,
                           module_name(iter->owner));
        else
                seq_printf(m, "%0*lx %c %s\n",
                           (int)(2*sizeof(void*)),
                           iter->value, iter->type, iter->name);
        return 0;
}

struct seq_operations kallsyms_op = {
        .start = s_start,
        .next = s_next,
        .stop = s_stop,
        .show = s_show
};

static int kallsyms_open(struct inode *inode, struct file *file)
{
        /* We keep iterator in m->private, since normal case is to
         * s_start from where we left off, so we avoid O(N^2). */
        struct kallsym_iter *iter;
        int ret;

        iter = kmalloc(sizeof(*iter), GFP_KERNEL);
        if (!iter)
                return -ENOMEM;
        reset_iter(iter);

        ret = seq_open(file, &kallsyms_op);
        if (ret == 0)
                ((struct seq_file *)file->private_data)->private = iter;
        else
                kfree(iter);
        return ret;
}

static int kallsyms_release(struct inode *inode, struct file *file)
{
        struct seq_file *m = (struct seq_file *)file->private_data;
        kfree(m->private);
        return seq_release(inode, file);
}

static struct file_operations kallsyms_operations = {
        .open = kallsyms_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = kallsyms_release,
};

int __init kallsyms_init(void)
{
        struct proc_dir_entry *entry;

        entry = create_proc_entry("kallsyms", 0444, NULL);
        if (entry)
                entry->proc_fops = &kallsyms_operations;
        return 0;
}
__initcall(kallsyms_init);

EXPORT_SYMBOL(__print_symbol);