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kernel/extable.c
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// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Rewritten by Rusty Russell, on the backs of many others... Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM. |
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*/ |
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#include <linux/ftrace.h> |
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#include <linux/memory.h> |
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#include <linux/extable.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/init.h> |
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#include <linux/kprobes.h> |
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#include <linux/filter.h> |
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|
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#include <asm/sections.h> |
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#include <linux/uaccess.h> |
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/* * mutex protecting text section modification (dynamic code patching). * some users need to sleep (allocating memory...) while they hold this lock. * |
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* Note: Also protects SMP-alternatives modification on x86. * |
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* NOT exported to modules - patching kernel text is a really delicate matter. */ DEFINE_MUTEX(text_mutex); |
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extern struct exception_table_entry __start___ex_table[]; extern struct exception_table_entry __stop___ex_table[]; |
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/* Cleared by build time tools if the table is already sorted. */ |
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u32 __initdata __visible main_extable_sort_needed = 1; |
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/* Sort the kernel's built-in exception table */ void __init sort_main_extable(void) { |
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if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) { |
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pr_notice("Sorting __ex_table... "); |
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sort_extable(__start___ex_table, __stop___ex_table); |
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} |
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} |
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/* Given an address, look for it in the kernel exception table */ const struct exception_table_entry *search_kernel_exception_table(unsigned long addr) { return search_extable(__start___ex_table, __stop___ex_table - __start___ex_table, addr); } |
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/* 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; |
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e = search_kernel_exception_table(addr); |
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if (!e) e = search_module_extables(addr); return e; } |
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int init_kernel_text(unsigned long addr) |
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{ if (addr >= (unsigned long)_sinittext && |
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addr < (unsigned long)_einittext) |
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return 1; return 0; } |
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int notrace core_kernel_text(unsigned long addr) |
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{ if (addr >= (unsigned long)_stext && |
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addr < (unsigned long)_etext) |
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return 1; |
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if (system_state < SYSTEM_RUNNING && |
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init_kernel_text(addr)) |
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return 1; return 0; } |
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/** * 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. */ |
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int core_kernel_data(unsigned long addr) { |
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if (addr >= (unsigned long)_sdata && |
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addr < (unsigned long)_edata) return 1; return 0; } |
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int __kernel_text_address(unsigned long addr) |
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{ |
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if (kernel_text_address(addr)) |
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return 1; |
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/* * 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; |
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} int kernel_text_address(unsigned long addr) { |
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bool no_rcu; int ret = 1; |
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if (core_kernel_text(addr)) return 1; |
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/* * 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 * and is_bpf_text_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(); |
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if (is_module_text_address(addr)) |
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goto out; |
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if (is_ftrace_trampoline(addr)) |
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goto out; |
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if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr)) |
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goto out; |
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if (is_bpf_text_address(addr)) |
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goto out; ret = 0; out: if (no_rcu) rcu_nmi_exit(); return ret; |
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} |
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/* * 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; |
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return is_module_text_address(addr); |
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} |