1 // SPDX-License-Identifier: GPL-2.0-only
3  * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
5  * Rewritten and vastly simplified by Rusty Russell for in-kernel
42 static unsigned int kallsyms_expand_symbol(unsigned int off,  in kallsyms_expand_symbol()  argument
50 	data = &kallsyms_names[off];  in kallsyms_expand_symbol()
53 	off++;  in kallsyms_expand_symbol()
59 		off++;  in kallsyms_expand_symbol()
66 	off += len;  in kallsyms_expand_symbol()
75 		len--;  in kallsyms_expand_symbol()
83 				maxlen--;  in kallsyms_expand_symbol()
95 	return off;  in kallsyms_expand_symbol()
102 static char kallsyms_get_symbol_type(unsigned int off)  in kallsyms_get_symbol_type()  argument
108 	return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];  in kallsyms_get_symbol_type()
146 	return name - kallsyms_names;  in get_symbol_offset()
154 	/* values are unsigned offsets if --absolute-percpu is not in effect */  in kallsyms_sym_address()
162 	/* ...and negative offsets are relative to kallsyms_relative_base - 1 */  in kallsyms_sym_address()
163 	return kallsyms_relative_base - 1 - kallsyms_offsets[idx];  in kallsyms_sym_address()
178 	 * - foo.llvm.[0-9a-f]+  in cleanup_symbol_name()
214 	unsigned int seq, off;  in kallsyms_lookup_names()  local
218 	high = kallsyms_num_syms - 1;  in kallsyms_lookup_names()
221 		mid = low + (high - low) / 2;  in kallsyms_lookup_names()
223 		off = get_symbol_offset(seq);  in kallsyms_lookup_names()
224 		kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));  in kallsyms_lookup_names()
229 			high = mid - 1;  in kallsyms_lookup_names()
235 		return -ESRCH;  in kallsyms_lookup_names()
239 		seq = get_symbol_seq(low - 1);  in kallsyms_lookup_names()
240 		off = get_symbol_offset(seq);  in kallsyms_lookup_names()
241 		kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));  in kallsyms_lookup_names()
244 		low--;  in kallsyms_lookup_names()
250 		while (high < kallsyms_num_syms - 1) {  in kallsyms_lookup_names()
252 			off = get_symbol_offset(seq);  in kallsyms_lookup_names()
253 			kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));  in kallsyms_lookup_names()
290 	unsigned int off;  in kallsyms_on_each_symbol()  local
293 	for (i = 0, off = 0; i < kallsyms_num_syms; i++) {  in kallsyms_on_each_symbol()
294 		off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));  in kallsyms_on_each_symbol()
338 	while (high - low > 1) {  in get_symbol_pos()
339 		mid = low + (high - low) / 2;  in get_symbol_pos()
350 	while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))  in get_symbol_pos()
351 		--low;  in get_symbol_pos()
355 	/* Search for next non-aliased symbol. */  in get_symbol_pos()
374 		*symbolsize = symbol_end - symbol_start;  in get_symbol_pos()
376 		*offset = addr - symbol_start;  in get_symbol_pos()
404 	namebuf[KSYM_NAME_LEN - 1] = 0;  in kallsyms_lookup_buildid()
441  * - modname is set to NULL if it's in the kernel.
442  * - We guarantee that the returned name is valid until we reschedule even if.
444  * - We also guarantee that modname will be valid until rescheduled.
460 	symname[KSYM_NAME_LEN - 1] = '\0';  in lookup_symbol_name()
495 		return sprintf(buffer, "0x%lx", address - symbol_offset);  in __sprint_symbol()
500 	offset -= symbol_offset;  in __sprint_symbol()
523  * sprint_symbol - Look up a kernel symbol and return it in a text buffer
527  * This function looks up a kernel symbol with @address and stores its name,
531  * This function returns the number of bytes stored in @buffer.
540  * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
544  * This function looks up a kernel symbol with @address and stores its name,
548  * This function returns the number of bytes stored in @buffer.
557  * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
561  * This function looks up a kernel symbol with @address and stores its name
565  * This function returns the number of bytes stored in @buffer.
574  * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
578  * This function is for stack backtrace and does the same thing as
580  * tail-call to the function marked "noreturn", gcc optimized out code after
581  * the call so that the stack-saved return address could point outside of the
582  * caller. This function ensures that kallsyms will find the original caller
585  * This function returns the number of bytes stored in @buffer.
589 	return __sprint_symbol(buffer, address, -1, 1, 0);  in sprint_backtrace()
593  * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
597  * This function is for stack backtrace and does the same thing as
599  * tail-call to the function marked "noreturn", gcc optimized out code after
600  * the call so that the stack-saved return address could point outside of the
601  * caller. This function ensures that kallsyms will find the original caller
602  * by decreasing @address. This function also appends the module build ID to
605  * This function returns the number of bytes stored in @buffer.
609 	return __sprint_symbol(buffer, address, -1, 1, 1);  in sprint_backtrace_build_id()
629 	int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,  in get_ksymbol_mod()
630 				     &iter->value, &iter->type,  in get_ksymbol_mod()
631 				     iter->name, iter->module_name,  in get_ksymbol_mod()
632 				     &iter->exported);  in get_ksymbol_mod()
634 		iter->pos_mod_end = iter->pos;  in get_ksymbol_mod()
648 	int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,  in get_ksymbol_ftrace_mod()
649 					 &iter->value, &iter->type,  in get_ksymbol_ftrace_mod()
650 					 iter->name, iter->module_name,  in get_ksymbol_ftrace_mod()
651 					 &iter->exported);  in get_ksymbol_ftrace_mod()
653 		iter->pos_ftrace_mod_end = iter->pos;  in get_ksymbol_ftrace_mod()
664 	strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);  in get_ksymbol_bpf()
665 	iter->exported = 0;  in get_ksymbol_bpf()
666 	ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,  in get_ksymbol_bpf()
667 			      &iter->value, &iter->type,  in get_ksymbol_bpf()
668 			      iter->name);  in get_ksymbol_bpf()
670 		iter->pos_bpf_end = iter->pos;  in get_ksymbol_bpf()
684 	strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);  in get_ksymbol_kprobe()
685 	iter->exported = 0;  in get_ksymbol_kprobe()
686 	return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,  in get_ksymbol_kprobe()
687 				  &iter->value, &iter->type,  in get_ksymbol_kprobe()
688 				  iter->name) < 0 ? 0 : 1;  in get_ksymbol_kprobe()
694 	unsigned off = iter->nameoff;  in get_ksymbol_core()  local
696 	iter->module_name[0] = '\0';  in get_ksymbol_core()
697 	iter->value = kallsyms_sym_address(iter->pos);  in get_ksymbol_core()
699 	iter->type = kallsyms_get_symbol_type(off);  in get_ksymbol_core()
701 	off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));  in get_ksymbol_core()
703 	return off - iter->nameoff;  in get_ksymbol_core()
708 	iter->name[0] = '\0';  in reset_iter()
709 	iter->nameoff = get_symbol_offset(new_pos);  in reset_iter()
710 	iter->pos = new_pos;  in reset_iter()
712 		iter->pos_mod_end = 0;  in reset_iter()
713 		iter->pos_ftrace_mod_end = 0;  in reset_iter()
714 		iter->pos_bpf_end = 0;  in reset_iter()
720  * in iter->pos_..._end as each section is added, and so can be used to
721  * determine which get_ksymbol_...() function to call next.
725 	iter->pos = pos;  in update_iter_mod()
727 	if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&  in update_iter_mod()
731 	if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&  in update_iter_mod()
735 	if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&  in update_iter_mod()
750 	if (pos != iter->pos)  in update_iter()
753 	iter->nameoff += get_ksymbol_core(iter);  in update_iter()
754 	iter->pos++;  in update_iter()
763 	if (!update_iter(m->private, *pos))  in s_next()
770 	if (!update_iter(m->private, *pos))  in s_start()
772 	return m->private;  in s_start()
782 	struct kallsym_iter *iter = m->private;  in s_show()
785 	if (!iter->name[0])  in s_show()
788 	value = iter->show_value ? (void *)iter->value : NULL;  in s_show()
790 	if (iter->module_name[0]) {  in s_show()
797 		type = iter->exported ? toupper(iter->type) :  in s_show()
798 					tolower(iter->type);  in s_show()
800 			   type, iter->name, iter->module_name);  in s_show()
803 			   iter->type, iter->name);  in s_show()
833 	ctx.ksym = m ? m->private : NULL;  in ksym_prog_seq_show()
866 	iter->show_value = kallsyms_show_value(current_cred());  in bpf_iter_ksym_init()
907 	 * We keep iterator in m->private, since normal case is to  in kallsyms_open()
908 	 * s_start from where we left off, so we avoid doing  in kallsyms_open()
914 		return -ENOMEM;  in kallsyms_open()
921 	iter->show_value = kallsyms_show_value(file->f_cred);  in kallsyms_open()