/* Rewritten by Rusty Russell, on the backs of many others...   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.     This program is free software; you can redistribute it and/or modify    it under the terms of the GNU General Public License as published by    the Free Software Foundation; either version 2 of the License, or    (at your option) any later version.     This program is distributed in the hope that it will be useful,    but WITHOUT ANY WARRANTY; without even the implied warranty of    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    GNU General Public License for more details.     You should have received a copy of the GNU General Public License    along with this program; if not, write to the Free Software    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA*/#include <linux/ftrace.h>#include <linux/memory.h>#include <linux/extable.h>#include <linux/module.h>#include <linux/mutex.h>#include <linux/init.h>#include <linux/kprobes.h>#include <linux/filter.h> #include <asm/sections.h>#include <linux/uaccess.h> /* * mutex protecting text section modification (dynamic code patching). * some users need to sleep (allocating memory...) while they hold this lock. * * NOT exported to modules - patching kernel text is a really delicate matter. */DEFINE_MUTEX(text_mutex); extern struct exception_table_entry __start___ex_table[];extern struct exception_table_entry __stop___ex_table[]; /* Cleared by build time tools if the table is already sorted. */u32 __initdata __visible main_extable_sort_needed = 1; /* Sort the kernel's built-in exception table */void __init sort_main_extable(void){	if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {		pr_notice("Sorting __ex_table...\n");		sort_extable(__start___ex_table, __stop___ex_table);	}} /* Given an address, look for it in the exception tables. */const struct exception_table_entry *search_exception_tables(unsigned long addr){	const struct exception_table_entry *e; 	e = search_extable(__start___ex_table, __stop___ex_table-1, addr);	if (!e)		e = search_module_extables(addr);	return e;} static inline int init_kernel_text(unsigned long addr){	if (addr >= (unsigned long)_sinittext &&	    addr < (unsigned long)_einittext)		return 1;	return 0;} int core_kernel_text(unsigned long addr){	if (addr >= (unsigned long)_stext &&	    addr < (unsigned long)_etext)		return 1; 	if (system_state == SYSTEM_BOOTING &&	    init_kernel_text(addr))		return 1;	return 0;} /** * core_kernel_data - tell if addr points to kernel data * @addr: address to test * * Returns true if @addr passed in is from the core kernel data * section. * * Note: On some archs it may return true for core RODATA, and false *  for others. But will always be true for core RW data. */int core_kernel_data(unsigned long addr){	if (addr >= (unsigned long)_sdata &&	    addr < (unsigned long)_edata)		return 1;	return 0;} int __kernel_text_address(unsigned long addr){	if (core_kernel_text(addr))		return 1;	if (is_module_text_address(addr))		return 1;	if (is_ftrace_trampoline(addr))		return 1;	if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))		return 1;	if (is_bpf_text_address(addr))		return 1;	/*	 * There might be init symbols in saved stacktraces.	 * Give those symbols a chance to be printed in	 * backtraces (such as lockdep traces).	 *	 * Since we are after the module-symbols check, there's	 * no danger of address overlap:	 */	if (init_kernel_text(addr))		return 1;	return 0;} int kernel_text_address(unsigned long addr){	if (core_kernel_text(addr))		return 1;	if (is_module_text_address(addr))		return 1;	if (is_ftrace_trampoline(addr))		return 1;	if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))		return 1;	if (is_bpf_text_address(addr))		return 1;	return 0;} /* * On some architectures (PPC64, IA64) function pointers * are actually only tokens to some data that then holds the * real function address. As a result, to find if a function * pointer is part of the kernel text, we need to do some * special dereferencing first. */int func_ptr_is_kernel_text(void *ptr){	unsigned long addr;	addr = (unsigned long) dereference_function_descriptor(ptr);	if (core_kernel_text(addr))		return 1;	return is_module_text_address(addr);}