diff options
Diffstat (limited to 'kernel/kallsyms.c')
| -rw-r--r-- | kernel/kallsyms.c | 608 |
1 files changed, 608 insertions, 0 deletions
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c new file mode 100644 index 000000000..5c5987f10 --- /dev/null +++ b/kernel/kallsyms.c @@ -0,0 +1,608 @@ +/* + * 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 + * + * ChangeLog: + * + * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> + * Changed the compression method from stem compression to "table lookup" + * compression (see scripts/kallsyms.c for a more complete description) + */ +#include <linux/kallsyms.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/seq_file.h> +#include <linux/fs.h> +#include <linux/kdb.h> +#include <linux/err.h> +#include <linux/proc_fs.h> +#include <linux/sched.h> /* for cond_resched */ +#include <linux/mm.h> +#include <linux/ctype.h> +#include <linux/slab.h> +#include <linux/compiler.h> + +#include <asm/sections.h> + +#ifdef CONFIG_KALLSYMS_ALL +#define all_var 1 +#else +#define all_var 0 +#endif + +/* + * These will be re-linked against their real values + * during the second link stage. + */ +extern const unsigned long kallsyms_addresses[] __weak; +extern const u8 kallsyms_names[] __weak; + +/* + * Tell the compiler that the count isn't in the small data section if the arch + * has one (eg: FRV). + */ +extern const unsigned long kallsyms_num_syms +__attribute__((weak, section(".rodata"))); + +extern const u8 kallsyms_token_table[] __weak; +extern const u16 kallsyms_token_index[] __weak; + +extern const unsigned long kallsyms_markers[] __weak; + +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) || + arch_is_kernel_text(addr)) + return 1; + return in_gate_area_no_mm(addr); +} + +static inline int is_kernel(unsigned long addr) +{ + if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) + return 1; + return in_gate_area_no_mm(addr); +} + +static int is_ksym_addr(unsigned long addr) +{ + if (all_var) + return is_kernel(addr); + + return is_kernel_text(addr) || is_kernel_inittext(addr); +} + +/* + * Expand a compressed symbol data into the resulting uncompressed string, + * if uncompressed string is too long (>= maxlen), it will be truncated, + * given the offset to where the symbol is in the compressed stream. + */ +static unsigned int kallsyms_expand_symbol(unsigned int off, + char *result, size_t maxlen) +{ + int len, skipped_first = 0; + const u8 *tptr, *data; + + /* Get the compressed symbol length from the first symbol byte. */ + data = &kallsyms_names[off]; + len = *data; + data++; + + /* + * Update the offset to return the offset for the next symbol on + * the compressed stream. + */ + off += len + 1; + + /* + * For every byte on the compressed symbol data, copy the table + * entry for that byte. + */ + while (len) { + tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; + data++; + len--; + + while (*tptr) { + if (skipped_first) { + if (maxlen <= 1) + goto tail; + *result = *tptr; + result++; + maxlen--; + } else + skipped_first = 1; + tptr++; + } + } + +tail: + if (maxlen) + *result = '\0'; + + /* Return to offset to the next symbol. */ + return off; +} + +/* + * Get symbol type information. This is encoded as a single char at the + * beginning of the symbol name. + */ +static char kallsyms_get_symbol_type(unsigned int off) +{ + /* + * Get just the first code, look it up in the token table, + * and return the first char from this token. + */ + return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; +} + + +/* + * Find the offset on the compressed stream given and index in the + * kallsyms array. + */ +static unsigned int get_symbol_offset(unsigned long pos) +{ + const u8 *name; + int i; + + /* + * Use the closest marker we have. We have markers every 256 positions, + * so that should be close enough. + */ + name = &kallsyms_names[kallsyms_markers[pos >> 8]]; + + /* + * Sequentially scan all the symbols up to the point we're searching + * for. Every symbol is stored in a [<len>][<len> bytes of data] format, + * so we just need to add the len to the current pointer for every + * symbol we wish to skip. + */ + for (i = 0; i < (pos & 0xFF); i++) + name = name + (*name) + 1; + + return name - kallsyms_names; +} + +/* Lookup the address for this symbol. Returns 0 if not found. */ +unsigned long kallsyms_lookup_name(const char *name) +{ + char namebuf[KSYM_NAME_LEN]; + unsigned long i; + unsigned int off; + + for (i = 0, off = 0; i < kallsyms_num_syms; i++) { + off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); + + if (strcmp(namebuf, name) == 0) + return kallsyms_addresses[i]; + } + return module_kallsyms_lookup_name(name); +} +EXPORT_SYMBOL_GPL(kallsyms_lookup_name); + +int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, + unsigned long), + void *data) +{ + char namebuf[KSYM_NAME_LEN]; + unsigned long i; + unsigned int off; + int ret; + + for (i = 0, off = 0; i < kallsyms_num_syms; i++) { + off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); + ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); + if (ret != 0) + return ret; + } + return module_kallsyms_on_each_symbol(fn, data); +} +EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); + +static unsigned long get_symbol_pos(unsigned long addr, + unsigned long *symbolsize, + unsigned long *offset) +{ + unsigned long symbol_start = 0, symbol_end = 0; + unsigned long i, low, high, mid; + + /* This kernel should never had been booted. */ + BUG_ON(!kallsyms_addresses); + + /* Do a binary search on the sorted kallsyms_addresses array. */ + low = 0; + high = kallsyms_num_syms; + + while (high - low > 1) { + mid = low + (high - low) / 2; + if (kallsyms_addresses[mid] <= addr) + low = mid; + else + high = mid; + } + + /* + * Search for the first aliased symbol. Aliased + * symbols are symbols with the same address. + */ + while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) + --low; + + symbol_start = kallsyms_addresses[low]; + + /* Search for next non-aliased symbol. */ + for (i = low + 1; i < kallsyms_num_syms; i++) { + if (kallsyms_addresses[i] > symbol_start) { + symbol_end = kallsyms_addresses[i]; + break; + } + } + + /* If we found no next symbol, we use the end of the section. */ + if (!symbol_end) { + if (is_kernel_inittext(addr)) + symbol_end = (unsigned long)_einittext; + else if (all_var) + symbol_end = (unsigned long)_end; + else + symbol_end = (unsigned long)_etext; + } + + if (symbolsize) + *symbolsize = symbol_end - symbol_start; + if (offset) + *offset = addr - symbol_start; + + return low; +} + +/* + * Lookup an address but don't bother to find any names. + */ +int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, + unsigned long *offset) +{ + char namebuf[KSYM_NAME_LEN]; + if (is_ksym_addr(addr)) + return !!get_symbol_pos(addr, symbolsize, offset); + + return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf); +} + +/* + * 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) +{ + namebuf[KSYM_NAME_LEN - 1] = 0; + namebuf[0] = 0; + + if (is_ksym_addr(addr)) { + unsigned long pos; + + pos = get_symbol_pos(addr, symbolsize, offset); + /* Grab name */ + kallsyms_expand_symbol(get_symbol_offset(pos), + namebuf, KSYM_NAME_LEN); + if (modname) + *modname = NULL; + return namebuf; + } + + /* See if it's in a module. */ + return module_address_lookup(addr, symbolsize, offset, modname, + namebuf); +} + +int lookup_symbol_name(unsigned long addr, char *symname) +{ + symname[0] = '\0'; + symname[KSYM_NAME_LEN - 1] = '\0'; + + if (is_ksym_addr(addr)) { + unsigned long pos; + + pos = get_symbol_pos(addr, NULL, NULL); + /* Grab name */ + kallsyms_expand_symbol(get_symbol_offset(pos), + symname, KSYM_NAME_LEN); + return 0; + } + /* See if it's in a module. */ + return lookup_module_symbol_name(addr, symname); +} + +int lookup_symbol_attrs(unsigned long addr, unsigned long *size, + unsigned long *offset, char *modname, char *name) +{ + name[0] = '\0'; + name[KSYM_NAME_LEN - 1] = '\0'; + + if (is_ksym_addr(addr)) { + unsigned long pos; + + pos = get_symbol_pos(addr, size, offset); + /* Grab name */ + kallsyms_expand_symbol(get_symbol_offset(pos), + name, KSYM_NAME_LEN); + modname[0] = '\0'; + return 0; + } + /* See if it's in a module. */ + return lookup_module_symbol_attrs(addr, size, offset, modname, name); +} + +/* Look up a kernel symbol and return it in a text buffer. */ +static int __sprint_symbol(char *buffer, unsigned long address, + int symbol_offset, int add_offset) +{ + char *modname; + const char *name; + unsigned long offset, size; + int len; + + address += symbol_offset; + name = kallsyms_lookup(address, &size, &offset, &modname, buffer); + if (!name) + return sprintf(buffer, "0x%lx", address - symbol_offset); + + if (name != buffer) + strcpy(buffer, name); + len = strlen(buffer); + offset -= symbol_offset; + + if (add_offset) + len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); + + if (modname) + len += sprintf(buffer + len, " [%s]", modname); + + return len; +} + +/** + * sprint_symbol - Look up a kernel symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function looks up a kernel symbol with @address and stores its name, + * offset, size and module name to @buffer if possible. If no symbol was found, + * just saves its @address as is. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_symbol(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, 0, 1); +} +EXPORT_SYMBOL_GPL(sprint_symbol); + +/** + * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function looks up a kernel symbol with @address and stores its name + * and module name to @buffer if possible. If no symbol was found, just saves + * its @address as is. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_symbol_no_offset(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, 0, 0); +} +EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); + +/** + * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function is for stack backtrace and does the same thing as + * sprint_symbol() but with modified/decreased @address. If there is a + * tail-call to the function marked "noreturn", gcc optimized out code after + * the call so that the stack-saved return address could point outside of the + * caller. This function ensures that kallsyms will find the original caller + * by decreasing @address. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_backtrace(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, -1, 1); +} + +/* Look up a kernel symbol and print it to the kernel messages. */ +void __print_symbol(const char *fmt, unsigned long address) +{ + char buffer[KSYM_SYMBOL_LEN]; + + sprint_symbol(buffer, address); + + printk(fmt, buffer); +} +EXPORT_SYMBOL(__print_symbol); + +/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ +struct kallsym_iter { + loff_t pos; + unsigned long value; + unsigned int nameoff; /* If iterating in core kernel symbols. */ + char type; + char name[KSYM_NAME_LEN]; + char module_name[MODULE_NAME_LEN]; + int exported; +}; + +static int get_ksymbol_mod(struct kallsym_iter *iter) +{ + if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, + &iter->type, iter->name, iter->module_name, + &iter->exported) < 0) + return 0; + return 1; +} + +/* Returns space to next name. */ +static unsigned long get_ksymbol_core(struct kallsym_iter *iter) +{ + unsigned off = iter->nameoff; + + iter->module_name[0] = '\0'; + iter->value = kallsyms_addresses[iter->pos]; + + iter->type = kallsyms_get_symbol_type(off); + + off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); + + return off - iter->nameoff; +} + +static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) +{ + iter->name[0] = '\0'; + iter->nameoff = get_symbol_offset(new_pos); + iter->pos = new_pos; +} + +/* 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 not on the desired position, reset to new position. */ + if (pos != iter->pos) + reset_iter(iter, pos); + + iter->nameoff += get_ksymbol_core(iter); + iter->pos++; + + 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->module_name[0]) { + char type; + + /* + * Label it "global" if it is exported, + * "local" if not exported. + */ + type = iter->exported ? toupper(iter->type) : + tolower(iter->type); + seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value, + type, iter->name, iter->module_name); + } else + seq_printf(m, "%pK %c %s\n", (void *)iter->value, + iter->type, iter->name); + return 0; +} + +static const 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 doing + * using get_symbol_offset for every symbol. + */ + struct kallsym_iter *iter; + iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); + if (!iter) + return -ENOMEM; + reset_iter(iter, 0); + + return 0; +} + +#ifdef CONFIG_KGDB_KDB +const char *kdb_walk_kallsyms(loff_t *pos) +{ + static struct kallsym_iter kdb_walk_kallsyms_iter; + if (*pos == 0) { + memset(&kdb_walk_kallsyms_iter, 0, + sizeof(kdb_walk_kallsyms_iter)); + reset_iter(&kdb_walk_kallsyms_iter, 0); + } + while (1) { + if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) + return NULL; + ++*pos; + /* Some debugging symbols have no name. Ignore them. */ + if (kdb_walk_kallsyms_iter.name[0]) + return kdb_walk_kallsyms_iter.name; + } +} +#endif /* CONFIG_KGDB_KDB */ + +static const struct file_operations kallsyms_operations = { + .open = kallsyms_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release_private, +}; + +static int __init kallsyms_init(void) +{ + proc_create("kallsyms", 0444, NULL, &kallsyms_operations); + return 0; +} +device_initcall(kallsyms_init); |