| | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| | 2 | /* Rewritten by Rusty Russell, on the backs of many others... |
| | 3 | Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM. |
| | 4 | |
| | 5 | */ |
| | 6 | #include <linux/ftrace.h> |
| | 7 | #include <linux/memory.h> |
| | 8 | #include <linux/extable.h> |
| | 9 | #include <linux/module.h> |
| | 10 | #include <linux/mutex.h> |
| | 11 | #include <linux/init.h> |
| | 12 | #include <linux/kprobes.h> |
| | 13 | #include <linux/filter.h> |
| | 14 | |
| | 15 | #include <asm/sections.h> |
| | 16 | #include <linux/uaccess.h> |
| | 17 | |
| | 18 | /* |
| | 19 | * mutex protecting text section modification (dynamic code patching). |
| | 20 | * some users need to sleep (allocating memory...) while they hold this lock. |
| | 21 | * |
| | 22 | * Note: Also protects SMP-alternatives modification on x86. |
| | 23 | * |
| | 24 | * NOT exported to modules - patching kernel text is a really delicate matter. |
| | 25 | */ |
| | 26 | DEFINE_MUTEX(text_mutex); |
| | 27 | |
| | 28 | extern struct exception_table_entry __start___ex_table[]; |
| | 29 | extern struct exception_table_entry __stop___ex_table[]; |
| | 30 | |
| | 31 | /* Cleared by build time tools if the table is already sorted. */ |
| | 32 | u32 __initdata __visible main_extable_sort_needed = 1; |
| | 33 | |
| | 34 | /* Sort the kernel's built-in exception table */ |
| | 35 | void __init sort_main_extable(void) |
| | 36 | { |
| | 37 | if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) { |
| | 38 | pr_notice("Sorting __ex_table...\n"); |
| | 39 | sort_extable(__start___ex_table, __stop___ex_table); |
| | 40 | } |
| | 41 | } |
| | 42 | |
| | 43 | /* Given an address, look for it in the exception tables. */ |
| | 44 | const struct exception_table_entry *search_exception_tables(unsigned long addr) |
| | 45 | { |
| | 46 | const struct exception_table_entry *e; |
| | 47 | |
| | 48 | e = search_extable(__start___ex_table, |
| | 49 | __stop___ex_table - __start___ex_table, addr); |
| | 50 | if (!e) |
| | 51 | e = search_module_extables(addr); |
| | 52 | return e; |
| | 53 | } |
| | 54 | |
| | 55 | int init_kernel_text(unsigned long addr) |
| | 56 | { |
| | 57 | if (addr >= (unsigned long)_sinittext && |
| | 58 | addr < (unsigned long)_einittext) |
| | 59 | return 1; |
| | 60 | return 0; |
| | 61 | } |
| | 62 | |
| | 63 | int notrace core_kernel_text(unsigned long addr) |
| | 64 | { |
| | 65 | if (addr >= (unsigned long)_stext && |
| | 66 | addr < (unsigned long)_etext) |
| | 67 | return 1; |
| | 68 | |
| | 69 | if (system_state < SYSTEM_RUNNING && |
| | 70 | init_kernel_text(addr)) |
| | 71 | return 1; |
| | 72 | return 0; |
| | 73 | } |
| | 74 | |
| | 75 | /** |
| | 76 | * core_kernel_data - tell if addr points to kernel data |
| | 77 | * @addr: address to test |
| | 78 | * |
| | 79 | * Returns true if @addr passed in is from the core kernel data |
| | 80 | * section. |
| | 81 | * |
| | 82 | * Note: On some archs it may return true for core RODATA, and false |
| | 83 | * for others. But will always be true for core RW data. |
| | 84 | */ |
| | 85 | int core_kernel_data(unsigned long addr) |
| | 86 | { |
| | 87 | if (addr >= (unsigned long)_sdata && |
| | 88 | addr < (unsigned long)_edata) |
| | 89 | return 1; |
| | 90 | return 0; |
| | 91 | } |
| | 92 | |
| | 93 | int __kernel_text_address(unsigned long addr) |
| | 94 | { |
| | 95 | if (kernel_text_address(addr)) |
| | 96 | return 1; |
| | 97 | /* |
| | 98 | * There might be init symbols in saved stacktraces. |
| | 99 | * Give those symbols a chance to be printed in |
| | 100 | * backtraces (such as lockdep traces). |
| | 101 | * |
| | 102 | * Since we are after the module-symbols check, there's |
| | 103 | * no danger of address overlap: |
| | 104 | */ |
| | 105 | if (init_kernel_text(addr)) |
| | 106 | return 1; |
| | 107 | return 0; |
| | 108 | } |
| | 109 | |
| | 110 | int kernel_text_address(unsigned long addr) |
| | 111 | { |
| | 112 | bool no_rcu; |
| | 113 | int ret = 1; |
| | 114 | |
| | 115 | if (core_kernel_text(addr)) |
| | 116 | return 1; |
| | 117 | |
| | 118 | /* |
| | 119 | * If a stack dump happens while RCU is not watching, then |
| | 120 | * RCU needs to be notified that it requires to start |
| | 121 | * watching again. This can happen either by tracing that |
| | 122 | * triggers a stack trace, or a WARN() that happens during |
| | 123 | * coming back from idle, or cpu on or offlining. |
| | 124 | * |
| | 125 | * is_module_text_address() as well as the kprobe slots |
| | 126 | * and is_bpf_text_address() require RCU to be watching. |
| | 127 | */ |
| | 128 | no_rcu = !rcu_is_watching(); |
| | 129 | |
| | 130 | /* Treat this like an NMI as it can happen anywhere */ |
| | 131 | if (no_rcu) |
| | 132 | rcu_nmi_enter(); |
| | 133 | |
| | 134 | if (is_module_text_address(addr)) |
| | 135 | goto out; |
| | 136 | if (is_ftrace_trampoline(addr)) |
| | 137 | goto out; |
| | 138 | if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr)) |
| | 139 | goto out; |
| | 140 | if (is_bpf_text_address(addr)) |
| | 141 | goto out; |
| | 142 | ret = 0; |
| | 143 | out: |
| | 144 | if (no_rcu) |
| | 145 | rcu_nmi_exit(); |
| | 146 | |
| | 147 | return ret; |
| | 148 | } |
| | 149 | |
| | 150 | /* |
| | 151 | * On some architectures (PPC64, IA64) function pointers |
| | 152 | * are actually only tokens to some data that then holds the |
| | 153 | * real function address. As a result, to find if a function |
| | 154 | * pointer is part of the kernel text, we need to do some |
| | 155 | * special dereferencing first. |
| | 156 | */ |
| | 157 | int func_ptr_is_kernel_text(void *ptr) |
| | 158 | { |
| | 159 | unsigned long addr; |
| | 160 | addr = (unsigned long) dereference_function_descriptor(ptr); |
| | 161 | if (core_kernel_text(addr)) |
| | 162 | return 1; |
| | 163 | return is_module_text_address(addr); |
| | 164 | } |
projects / linux-2.6-block.git / blame_incremental