// SPDX-License-Identifier: GPL-2.0-or-later/* Rewritten by Rusty Russell, on the backs of many others...   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM. */#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. * * Note: Also protects SMP-alternatives modification on x86. * * 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 kernel exception table */conststruct exception_table_entry *search_kernel_exception_table(unsigned long addr){	return search_extable(__start___ex_table,			      __stop___ex_table - __start___ex_table, addr);} /* 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_kernel_exception_table(addr);	if (!e)		e = search_module_extables(addr);	if (!e)		e = search_bpf_extables(addr);	return e;} int notrace core_kernel_text(unsigned long addr){	if (is_kernel_text(addr))		return 1; 	if (system_state < SYSTEM_FREEING_INITMEM &&	    is_kernel_inittext(addr))		return 1;	return 0;} int __kernel_text_address(unsigned long addr){	if (kernel_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 (is_kernel_inittext(addr))		return 1;	return 0;} int kernel_text_address(unsigned long addr){	bool no_rcu;	int ret = 1; 	if (core_kernel_text(addr))		return 1; 	/*	 * If a stack dump happens while RCU is not watching, then	 * RCU needs to be notified that it requires to start	 * watching again. This can happen either by tracing that	 * triggers a stack trace, or a WARN() that happens during	 * coming back from idle, or cpu on or offlining.	 *	 * is_module_text_address() as well as the kprobe slots,	 * is_bpf_text_address() and is_bpf_image_address require	 * RCU to be watching.	 */	no_rcu = !rcu_is_watching(); 	/* Treat this like an NMI as it can happen anywhere */	if (no_rcu)		rcu_nmi_enter(); 	if (is_module_text_address(addr))		goto out;	if (is_ftrace_trampoline(addr))		goto out;	if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))		goto out;	if (is_bpf_text_address(addr))		goto out;	ret = 0;out:	if (no_rcu)		rcu_nmi_exit(); 	return ret;} /* * 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);}