/* * 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/err.h> #include <linux/proc_fs.h> #include <linux/sched.h> /* for cond_resched */ #include <linux/mm.h> #include <linux/ctype.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[] __attribute__((weak)); extern const unsigned long kallsyms_num_syms __attribute__((weak)); extern const u8 kallsyms_names[] __attribute__((weak)); extern const u8 kallsyms_token_table[] __attribute__((weak)); extern const u16 kallsyms_token_index[] __attribute__((weak)); extern const unsigned long kallsyms_markers[] __attribute__((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_extratext(unsigned long addr) { if (addr >= (unsigned long)_sextratext && addr <= (unsigned long)_eextratext) 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 in_gate_area_no_task(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_task(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) || is_kernel_extratext(addr); } /* expand a compressed symbol data into the resulting uncompressed string, given the offset to where the symbol is in the compressed stream */ static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) { 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) { *result = *tptr; result++; } else skipped_first = 1; tptr++; } } *result = '\0'; /* return to offset to the next symbol */ return off; } /* get symbol type information. This is encoded as a single char at the * begining 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+1]; unsigned long i; unsigned int off; for (i = 0, off = 0; i < kallsyms_num_syms; i++) { off = kallsyms_expand_symbol(off, namebuf); if (strcmp(namebuf, name) == 0) return kallsyms_addresses[i]; } return module_kallsyms_lookup_name(name); } 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) / 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; } *symbolsize = symbol_end - symbol_start; *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) { if (is_ksym_addr(addr)) return !!get_symbol_pos(addr, symbolsize, offset); return !!module_address_lookup(addr, symbolsize, offset, NULL); } /* * 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) { const char *msym; namebuf[KSYM_NAME_LEN] = 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); *modname = NULL; 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; } /* Look up a kernel symbol and return it in a text buffer. */ int sprint_symbol(char *buffer, unsigned long address) { char *modname; const char *name; unsigned long offset, size; char namebuf[KSYM_NAME_LEN+1]; name = kallsyms_lookup(address, &size, &offset, &modname, namebuf); if (!name) return sprintf(buffer, "0x%lx", address); else { if (modname) return sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset, size, modname); else return sprintf(buffer, "%s+%#lx/%#lx", name, offset, size); } } /* 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); } /* To avoid using get_symbol_offset for every symbol, 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]; }; 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, sizeof(iter->name)); if (iter->owner == NULL) return 0; /* Label it "global" if it is exported, "local" if not exported. */ iter->type = is_exported(iter->name, iter->owner) ? toupper(iter->type) : tolower(iter->type); return 1; } /* Returns space to next name. */ static unsigned long get_ksymbol_core(struct kallsym_iter *iter) { unsigned off = iter->nameoff; iter->owner = NULL; iter->value = kallsyms_addresses[iter->pos]; iter->type = kallsyms_get_symbol_type(off); off = kallsyms_expand_symbol(off, 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->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; } 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; int ret; iter = kmalloc(sizeof(*iter), GFP_KERNEL); if (!iter) return -ENOMEM; reset_iter(iter, 0); 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 const struct file_operations kallsyms_operations = { .open = kallsyms_open, .read = seq_read, .llseek = seq_lseek, .release = kallsyms_release, }; static 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); EXPORT_SYMBOL_GPL(sprint_symbol);